2.1.0

Aromatic bond display option

CHANGELOG.md

@@ -7,6 +7,12 @@ Note that since we don't clearly distinguish between a public and private interf
 ## [Unreleased]
 
 
+## [v2.1.0] - 2021-07-05
+
+- Add parameter for to display aromatic bonds as dashes next to solid cylinder/line.
+- Add backbone representation
+- Fix outline in orthographic mode and set default scale to 2.
+
 ## [v2.0.7] - 2021-06-23
 
 - Add ability to specify ``volumeIndex`` in ``Viewer.loadVolumeFromUrl`` to better support Volume Server inputs.

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "molstar",
-  "version": "2.0.7",
+  "version": "2.1.0",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "molstar",
-  "version": "2.0.7",
+  "version": "2.1.0",
   "description": "A comprehensive macromolecular library.",
   "homepage": "https://github.com/molstar/molstar#readme",
   "repository": {

src/mol-canvas3d/camera.ts

@@ -364,8 +364,9 @@ function updateClip(camera: Camera) {
         near = Math.max(Math.min(radiusMax, 5), near);
         far = Math.max(5, far);
     } else {
-        near = Math.max(0, near);
-        far = Math.max(0, far);
+        // not too close to 0 as it causes issues with outline rendering
+        near = Math.max(Math.min(radiusMax, 5), near);
+        far = Math.max(5, far);
     }
 
     if (near === far) {

src/mol-canvas3d/passes/postprocessing.ts

@@ -250,7 +250,7 @@ export const PostprocessingParams = {
     }, { cycle: true, description: 'Darken occluded crevices with the ambient occlusion effect' }),
     outline: PD.MappedStatic('off', {
         on: PD.Group({
-            scale: PD.Numeric(1, { min: 1, max: 5, step: 1 }),
+            scale: PD.Numeric(2, { min: 1, max: 5, step: 1 }),
             threshold: PD.Numeric(0.33, { min: 0.01, max: 1, step: 0.01 }),
         }),
         off: PD.Group({})
@@ -306,7 +306,8 @@ export class PostprocessingPass {
         this.nSamples = 1;
         this.blurKernelSize = 1;
 
-        this.target = webgl.createRenderTarget(width, height, false, 'uint8', 'nearest');
+        // needs to be linear for anti-aliasing pass
+        this.target = webgl.createRenderTarget(width, height, false, 'uint8', 'linear');
 
         this.outlinesTarget = webgl.createRenderTarget(width, height, false);
         this.outlinesRenderable = getOutlinesRenderable(webgl, depthTexture);
@@ -433,8 +434,12 @@ export class PostprocessingPass {
         }
 
         if (props.outline.name === 'on') {
-            const factor = Math.pow(1000, props.outline.params.threshold) / 1000;
-            const maxPossibleViewZDiff = factor * (camera.far - camera.near);
+            let { threshold } = props.outline.params;
+            // orthographic needs lower threshold
+            if (camera.state.mode === 'orthographic') threshold /= 5;
+            const factor = Math.pow(1000, threshold) / 1000;
+            // use radiusMax for stable outlines when zooming
+            const maxPossibleViewZDiff = factor * camera.state.radiusMax;
             const outlineScale = props.outline.params.scale - 1;
 
             ValueCell.updateIfChanged(this.outlinesRenderable.values.uNear, camera.near);
@@ -442,7 +447,6 @@ export class PostprocessingPass {
             ValueCell.updateIfChanged(this.outlinesRenderable.values.uMaxPossibleViewZDiff, maxPossibleViewZDiff);
 
             ValueCell.updateIfChanged(this.renderable.values.uMaxPossibleViewZDiff, maxPossibleViewZDiff);
-            ValueCell.updateIfChanged(this.renderable.values.uOutlineThreshold, props.outline.params.threshold);
             if (this.renderable.values.dOutlineScale.ref.value !== outlineScale) { needsUpdateMain = true; }
             ValueCell.updateIfChanged(this.renderable.values.dOutlineScale, outlineScale);
         }

src/mol-geo/geometry/mesh/builder/cylinder.ts

@@ -31,6 +31,7 @@ function setCylinderMat(m: Mat4, start: Vec3, dir: Vec3, length: number, matchDi
     // ensure the direction used to create the rotation is always pointing in the same
     // direction so the triangles of adjacent cylinder will line up
     if (matchDir) Vec3.matchDirection(tmpUp, up, tmpCylinderMatDir);
+    else Vec3.copy(tmpUp, up);
     Mat4.fromScaling(tmpCylinderMatScale, Vec3.set(tmpCylinderScale, 1, length, 1));
     Vec3.makeRotation(tmpCylinderMatRot, tmpUp, tmpCylinderMatDir);
     Mat4.mul(m, tmpCylinderMatRot, tmpCylinderMatScale);

src/mol-gl/shader/postprocessing.frag.ts

@@ -26,9 +26,6 @@ uniform bool uTransparentBackground;
 uniform float uOcclusionBias;
 uniform float uOcclusionRadius;
 
-uniform float uOutlineScale;
-uniform float uOutlineThreshold;
-
 uniform float uMaxPossibleViewZDiff;
 
 const vec3 occlusionColor = vec3(0.0);

src/mol-gl/webgl/texture.ts

@@ -186,6 +186,7 @@ export interface Texture {
     readonly format: number
     readonly internalFormat: number
     readonly type: number
+    readonly filter: number
 
     getWidth: () => number
     getHeight: () => number
@@ -326,6 +327,7 @@ export function createTexture(gl: GLRenderingContext, extensions: WebGLExtension
         format,
         internalFormat,
         type,
+        filter,
 
         getWidth: () => width,
         getHeight: () => height,
@@ -415,6 +417,7 @@ export function createNullTexture(gl?: GLRenderingContext): Texture {
         format: 0,
         internalFormat: 0,
         type: 0,
+        filter: 0,
 
         getWidth: () => 0,
         getHeight: () => 0,

src/mol-math/linear-algebra/3d/vec3.ts

@@ -474,7 +474,9 @@ namespace Vec3 {
 
     /** Computes the angle between 2 vectors, reports in radians. */
     export function angle(a: Vec3, b: Vec3) {
-        const theta = dot(a, b) / Math.sqrt(squaredMagnitude(a) * squaredMagnitude(b));
+        const denominator = Math.sqrt(squaredMagnitude(a) * squaredMagnitude(b));
+        if (denominator === 0) return Math.PI / 2;
+        const theta = dot(a, b) / denominator;
         return Math.acos(clamp(theta, -1, 1)); // clamp to avoid numerical problems
     }
 

src/mol-model-formats/structure/mol2.ts

@@ -6,7 +6,7 @@
 
 import { Column, Table } from '../../mol-data/db';
 import { Model } from '../../mol-model/structure/model';
-import { MoleculeType } from '../../mol-model/structure/model/types';
+import { BondType, MoleculeType } from '../../mol-model/structure/model/types';
 import { RuntimeContext, Task } from '../../mol-task';
 import { createModels } from './basic/parser';
 import { BasicSchema, createBasic } from './basic/schema';
@@ -74,8 +74,33 @@ async function getModels(mol2: Mol2File, ctx: RuntimeContext) {
         if (_models.frameCount > 0) {
             const indexA = Column.ofIntArray(Column.mapToArray(bonds.origin_atom_id, x => x - 1, Int32Array));
             const indexB = Column.ofIntArray(Column.mapToArray(bonds.target_atom_id, x => x - 1, Int32Array));
-            const order = Column.ofIntArray(Column.mapToArray(bonds.bond_type, x => x === 'ar' ? 1 : parseInt(x), Int8Array));
-            const pairBonds = IndexPairBonds.fromData({ pairs: { indexA, indexB, order }, count: atoms.count });
+            const order = Column.ofIntArray(Column.mapToArray(bonds.bond_type, x => {
+                switch (x) {
+                    case 'ar': // aromatic
+                    case 'am': // amide
+                    case 'un': // unknown
+                        return 1;
+                    case 'du': // dummy
+                    case 'nc': // not connected
+                        return 0;
+                    default:
+                        return parseInt(x);
+                }
+            }, Int8Array));
+            const flag = Column.ofIntArray(Column.mapToArray(bonds.bond_type, x => {
+                switch (x) {
+                    case 'ar': // aromatic
+                        return BondType.Flag.Aromatic | BondType.Flag.Covalent;
+                    case 'du': // dummy
+                    case 'nc': // not connected
+                        return BondType.Flag.None;
+                    case 'am': // amide
+                    case 'un': // unknown
+                    default:
+                        return BondType.Flag.Covalent;
+                }
+            }, Int8Array));
+            const pairBonds = IndexPairBonds.fromData({ pairs: { indexA, indexB, order, flag }, count: atoms.count });
 
             const first = _models.representative;
             IndexPairBonds.Provider.set(first, pairBonds);

src/mol-model/structure/model/types.ts

@@ -620,9 +620,9 @@ export namespace BondType {
         'covalent': Flag.Covalent,
         'metal-coordination': Flag.MetallicCoordination,
         'hydrogen-bond': Flag.HydrogenBond,
-        'disulfide': Flag.HydrogenBond,
-        'aromatic': Flag.HydrogenBond,
-        'computed': Flag.HydrogenBond,
+        'disulfide': Flag.Disulfide,
+        'aromatic': Flag.Aromatic,
+        'computed': Flag.Computed,
     };
     export type Names = keyof typeof Names
 

src/mol-model/structure/structure/structure.ts

@@ -368,13 +368,16 @@ class Structure {
 
     private _child: Structure | undefined;
     private _target: Structure | undefined;
+    private _proxy: Structure | undefined;
 
     /**
      * For `structure` with `parent` this returns a proxy that
      * targets `parent` and has `structure` attached as a child.
      */
     asParent(): Structure {
-        return this.parent ? new Structure(this.parent.units, this.parent.unitMap, this.parent.unitIndexMap, this.parent.state, { child: this, target: this.parent }) : this;
+        if (this._proxy) return this._proxy;
+        this._proxy = this.parent ? new Structure(this.parent.units, this.parent.unitMap, this.parent.unitIndexMap, this.parent.state, { child: this, target: this.parent }) : this;
+        return this._proxy;
     }
 
     get child(): Structure | undefined {

src/mol-model/structure/structure/unit/rings.ts

@@ -117,7 +117,6 @@ namespace UnitRing {
                 // comes e.g. from `chem_comp_bond.pdbx_aromatic_flag`
                 if (BondType.is(BondType.Flag.Aromatic, flags[j])) {
                     if (SortedArray.has(ring, b[j])) aromaticBondCount += 1;
-
                 }
             }
         }

src/mol-repr/structure/complex-visual.ts

@@ -118,6 +118,11 @@ export function ComplexVisual<G extends Geometry, P extends StructureParams & Ge
             updateState.createGeometry = true;
         }
 
+        if (currentStructure.child !== newStructure.child) {
+            // console.log('new child');
+            updateState.createGeometry = true;
+        }
+
         if (updateState.updateSize && !('uSize' in renderObject.values)) {
             updateState.createGeometry = true;
         }

src/mol-repr/structure/registry.ts

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2018-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
@@ -21,6 +21,7 @@ import { PuttyRepresentationProvider } from './representation/putty';
 import { SpacefillRepresentationProvider } from './representation/spacefill';
 import { LineRepresentationProvider } from './representation/line';
 import { GaussianVolumeRepresentationProvider } from './representation/gaussian-volume';
+import { BackboneRepresentationProvider } from './representation/backbone';
 
 export class StructureRepresentationRegistry extends RepresentationRegistry<Structure, StructureRepresentationState> {
     constructor() {
@@ -35,6 +36,7 @@ export class StructureRepresentationRegistry extends RepresentationRegistry<Stru
 export namespace StructureRepresentationRegistry {
     export const BuiltIn = {
         'cartoon': CartoonRepresentationProvider,
+        'backbone': BackboneRepresentationProvider,
         'ball-and-stick': BallAndStickRepresentationProvider,
         'carbohydrate': CarbohydrateRepresentationProvider,
         'ellipsoid': EllipsoidRepresentationProvider,

src/mol-repr/structure/representation/backbone.ts

@@ -1,29 +1,57 @@
-// /**
-//  * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
-//  *
-//  * @author Alexander Rose <alexander.rose@weirdbyte.de>
-//  */
+/**
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
 
-// import { PolymerBackboneVisual, PolymerBackboneParams } from '../visual/polymer-backbone-cylinder';
-// import { ParamDefinition as PD } from 'mol-util/param-definition';
-// import { UnitsRepresentation } from '../units-representation';
-// import { StructureRepresentation } from '../representation';
-// import { Representation } from 'mol-repr/representation';
-// import { ThemeRegistryContext } from 'mol-theme/theme';
-// import { Structure } from 'mol-model/structure';
+import { PolymerBackboneCylinderVisual, PolymerBackboneCylinderParams } from '../visual/polymer-backbone-cylinder';
+import { ParamDefinition as PD } from '../../../mol-util/param-definition';
+import { UnitsRepresentation } from '../units-representation';
+import { StructureRepresentation, StructureRepresentationProvider, StructureRepresentationStateBuilder } from '../representation';
+import { Representation, RepresentationContext, RepresentationParamsGetter } from '../../../mol-repr/representation';
+import { ThemeRegistryContext } from '../../../mol-theme/theme';
+import { Structure } from '../../../mol-model/structure';
+import { PolymerBackboneSphereParams, PolymerBackboneSphereVisual } from '../visual/polymer-backbone-sphere';
+import { PolymerGapParams, PolymerGapVisual } from '../visual/polymer-gap-cylinder';
 
-// export const BackboneParams = {
-//     ...PolymerBackboneParams,
-// }
-// export function getBackboneParams(ctx: ThemeRegistryContext, structure: Structure) {
-//     return BackboneParams // TODO return copy
-// }
-// export type BackboneProps = PD.DefaultValues<typeof BackboneParams>
+const BackboneVisuals = {
+    'polymer-backbone-cylinder': (ctx: RepresentationContext, getParams: RepresentationParamsGetter<Structure, PolymerBackboneCylinderParams>) => UnitsRepresentation('Polymer backbone cylinder', ctx, getParams, PolymerBackboneCylinderVisual),
+    'polymer-backbone-sphere': (ctx: RepresentationContext, getParams: RepresentationParamsGetter<Structure, PolymerBackboneSphereParams>) => UnitsRepresentation('Polymer backbone sphere', ctx, getParams, PolymerBackboneSphereVisual),
+    'polymer-gap': (ctx: RepresentationContext, getParams: RepresentationParamsGetter<Structure, PolymerGapParams>) => UnitsRepresentation('Polymer gap cylinder', ctx, getParams, PolymerGapVisual),
+};
 
-// export type BackboneRepresentation = StructureRepresentation<BackboneProps>
+export const BackboneParams = {
+    ...PolymerBackboneSphereParams,
+    ...PolymerBackboneCylinderParams,
+    ...PolymerGapParams,
+    sizeAspectRatio: PD.Numeric(1, { min: 0.1, max: 3, step: 0.1 }),
+    visuals: PD.MultiSelect(['polymer-backbone-cylinder', 'polymer-backbone-sphere', 'polymer-gap'], PD.objectToOptions(BackboneVisuals))
+};
+export type BackboneParams = typeof BackboneParams
+export function getBackboneParams(ctx: ThemeRegistryContext, structure: Structure) {
+    const params = PD.clone(BackboneParams);
+    let hasGaps = false;
+    structure.units.forEach(u => {
+        if (!hasGaps && u.gapElements.length) hasGaps = true;
+    });
+    params.visuals.defaultValue = ['polymer-backbone-cylinder', 'polymer-backbone-sphere'];
+    if (hasGaps) params.visuals.defaultValue.push('polymer-gap');
+    return params;
+}
 
-// export function BackboneRepresentation(defaultProps: BackboneProps): BackboneRepresentation {
-//     return Representation.createMulti('Backbone', defaultProps, [
-//         UnitsRepresentation('Polymer backbone cylinder', defaultProps, PolymerBackboneVisual)
-//     ])
-// }
+export type BackboneRepresentation = StructureRepresentation<BackboneParams>
+export function BackboneRepresentation(ctx: RepresentationContext, getParams: RepresentationParamsGetter<Structure, BackboneParams>): BackboneRepresentation {
+    return Representation.createMulti('Backbone', ctx, getParams, StructureRepresentationStateBuilder, BackboneVisuals as unknown as Representation.Def<Structure, BackboneParams>);
+}
+
+export const BackboneRepresentationProvider = StructureRepresentationProvider({
+    name: 'backbone',
+    label: 'Backbone',
+    description: 'Displays polymer backbone with cylinders and spheres.',
+    factory: BackboneRepresentation,
+    getParams: getBackboneParams,
+    defaultValues: PD.getDefaultValues(BackboneParams),
+    defaultColorTheme: { name: 'chain-id' },
+    defaultSizeTheme: { name: 'uniform' },
+    isApplicable: (structure: Structure) => structure.polymerResidueCount > 0,
+});

src/mol-repr/structure/units-representation.ts

@@ -66,7 +66,7 @@ export function UnitsRepresentation<P extends StructureParams>(label: string, ct
                     visuals.set(group.hashCode, { visual, group });
                     if (runtime.shouldUpdate) await runtime.update({ message: 'Creating or updating UnitsVisual', current: i, max: _groups.length });
                 }
-            } else if (structure && !Structure.areUnitIdsAndIndicesEqual(structure, _structure)) {
+            } else if (structure && (!Structure.areUnitIdsAndIndicesEqual(structure, _structure) || structure.child !== _structure.child)) {
                 // console.log(label, 'structures not equivalent');
                 // Tries to re-use existing visuals for the groups of the new structure.
                 // Creates additional visuals if needed, destroys left-over visuals.

src/mol-repr/structure/units-visual.ts

@@ -120,6 +120,11 @@ export function UnitsVisual<G extends Geometry, P extends StructureParams & Geom
             updateState.updateColor = true;
         }
 
+        if (currentStructureGroup.structure.child !== newStructureGroup.structure.child) {
+            // console.log('new child');
+            updateState.createGeometry = true;
+        }
+
         if (!deepEqual(newProps.unitKinds, currentProps.unitKinds)) {
             // console.log('new unitKinds');
             updateState.createGeometry = true;

src/mol-repr/structure/visual/aromatic-ring-mesh.ts

@@ -1 +0,0 @@
-// TODO

src/mol-repr/structure/visual/bond-inter-unit-cylinder.ts

@@ -11,7 +11,7 @@ import { Theme } from '../../../mol-theme/theme';
 import { Mesh } from '../../../mol-geo/geometry/mesh/mesh';
 import { Vec3 } from '../../../mol-math/linear-algebra';
 import { BitFlags, arrayEqual } from '../../../mol-util';
-import { createLinkCylinderImpostors, createLinkCylinderMesh, LinkStyle } from './util/link';
+import { createLinkCylinderImpostors, createLinkCylinderMesh, LinkBuilderProps, LinkStyle } from './util/link';
 import { ComplexMeshParams, ComplexVisual, ComplexMeshVisual, ComplexCylindersParams, ComplexCylindersVisual } from '../complex-visual';
 import { VisualUpdateState } from '../../util';
 import { BondType } from '../../../mol-model/structure/model/types';
@@ -34,22 +34,20 @@ function setRefPosition(pos: Vec3, structure: Structure, unit: Unit.Atomic, inde
 
 const tmpRef = Vec3();
 
-function getInterUnitBondCylinderBuilderProps(structure: Structure, theme: Theme, props: PD.Values<InterUnitBondCylinderParams>) {
+function getInterUnitBondCylinderBuilderProps(structure: Structure, theme: Theme, props: PD.Values<InterUnitBondCylinderParams>): LinkBuilderProps {
     const locE = StructureElement.Location.create(structure);
     const locB = Bond.Location(structure, undefined, undefined, structure, undefined, undefined);
 
     const bonds = structure.interUnitBonds;
     const { edgeCount, edges } = bonds;
-    const { sizeFactor, sizeAspectRatio, adjustCylinderLength } = props;
+    const { sizeFactor, sizeAspectRatio, adjustCylinderLength, aromaticBonds } = props;
 
     const delta = Vec3();
 
     let stub: undefined | ((edgeIndex: number) => boolean);
 
-    if (props.includeParent) {
-        const { child } = structure;
-        if (!child) throw new Error('expected child to exist');
-
+    const { child } = structure;
+    if (props.includeParent && child) {
         stub = (edgeIndex: number) => {
             const b = edges[edgeIndex];
             const childUnitA = child.unitMap.get(b.unitA);
@@ -137,13 +135,15 @@ function getInterUnitBondCylinderBuilderProps(structure: Structure, theme: Theme
             if (BondType.is(f, BondType.Flag.MetallicCoordination) || BondType.is(f, BondType.Flag.HydrogenBond)) {
                 // show metall coordinations and hydrogen bonds with dashed cylinders
                 return LinkStyle.Dashed;
-            } else if (o === 2) {
-                return LinkStyle.Double;
             } else if (o === 3) {
                 return LinkStyle.Triple;
-            } else {
-                return LinkStyle.Solid;
+            } else if (aromaticBonds && BondType.is(f, BondType.Flag.Aromatic)) {
+                return LinkStyle.Aromatic;
+            } else if (o === 2) {
+                return LinkStyle.Double;
             }
+
+            return LinkStyle.Solid;
         },
         radius: (edgeIndex: number) => {
             return radius(edgeIndex) * sizeAspectRatio;

src/mol-repr/structure/visual/bond-inter-unit-line.ts

@@ -10,7 +10,7 @@ import { Structure, StructureElement, Bond, Unit } from '../../../mol-model/stru
 import { Theme } from '../../../mol-theme/theme';
 import { Vec3 } from '../../../mol-math/linear-algebra';
 import { BitFlags, arrayEqual } from '../../../mol-util';
-import { LinkStyle, createLinkLines } from './util/link';
+import { LinkStyle, createLinkLines, LinkBuilderProps } from './util/link';
 import { ComplexVisual, ComplexLinesVisual, ComplexLinesParams } from '../complex-visual';
 import { VisualUpdateState } from '../../util';
 import { BondType } from '../../../mol-model/structure/model/types';
@@ -32,14 +32,14 @@ function setRefPosition(pos: Vec3, structure: Structure, unit: Unit.Atomic, inde
 function createInterUnitBondLines(ctx: VisualContext, structure: Structure, theme: Theme, props: PD.Values<InterUnitBondLineParams>, lines?: Lines) {
     const bonds = structure.interUnitBonds;
     const { edgeCount, edges } = bonds;
-    const { sizeFactor } = props;
+    const { sizeFactor, aromaticBonds } = props;
 
     if (!edgeCount) return Lines.createEmpty(lines);
 
     const ref = Vec3();
     const loc = StructureElement.Location.create();
 
-    const builderProps = {
+    const builderProps: LinkBuilderProps = {
         linkCount: edgeCount,
         referencePosition: (edgeIndex: number) => {
             const b = edges[edgeIndex];
@@ -73,13 +73,15 @@ function createInterUnitBondLines(ctx: VisualContext, structure: Structure, them
             if (BondType.is(f, BondType.Flag.MetallicCoordination) || BondType.is(f, BondType.Flag.HydrogenBond)) {
                 // show metall coordinations and hydrogen bonds with dashed cylinders
                 return LinkStyle.Dashed;
-            } else if (o === 2) {
-                return LinkStyle.Double;
             } else if (o === 3) {
                 return LinkStyle.Triple;
-            } else {
-                return LinkStyle.Solid;
+            }else if (aromaticBonds && BondType.is(f, BondType.Flag.Aromatic)) {
+                return LinkStyle.Aromatic;
+            } else if (o === 2) {
+                return LinkStyle.Double;
             }
+
+            return LinkStyle.Solid;
         },
         radius: (edgeIndex: number) => {
             const b = edges[edgeIndex];

src/mol-repr/structure/visual/bond-intra-unit-cylinder.ts

@@ -12,7 +12,7 @@ import { Theme } from '../../../mol-theme/theme';
 import { Mesh } from '../../../mol-geo/geometry/mesh/mesh';
 import { Vec3 } from '../../../mol-math/linear-algebra';
 import { arrayEqual } from '../../../mol-util';
-import { createLinkCylinderImpostors, createLinkCylinderMesh, LinkStyle } from './util/link';
+import { createLinkCylinderImpostors, createLinkCylinderMesh, LinkBuilderProps, LinkStyle } from './util/link';
 import { UnitsMeshParams, UnitsVisual, UnitsMeshVisual, StructureGroup, UnitsCylindersParams, UnitsCylindersVisual } from '../units-visual';
 import { VisualUpdateState } from '../../util';
 import { BondType } from '../../../mol-model/structure/model/types';
@@ -22,16 +22,17 @@ import { IntAdjacencyGraph } from '../../../mol-math/graph';
 import { WebGLContext } from '../../../mol-gl/webgl/context';
 import { Cylinders } from '../../../mol-geo/geometry/cylinders/cylinders';
 import { SortedArray } from '../../../mol-data/int';
+import { arrayIntersectionSize } from '../../../mol-util/array';
 
 // avoiding namespace lookup improved performance in Chrome (Aug 2020)
 const isBondType = BondType.is;
 
-function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Structure, theme: Theme, props: PD.Values<IntraUnitBondCylinderParams>) {
+function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Structure, theme: Theme, props: PD.Values<IntraUnitBondCylinderParams>): LinkBuilderProps {
     const elements = unit.elements;
     const bonds = unit.bonds;
     const { edgeCount, a, b, edgeProps, offset } = bonds;
     const { order: _order, flags: _flags } = edgeProps;
-    const { sizeFactor, sizeAspectRatio, adjustCylinderLength } = props;
+    const { sizeFactor, sizeAspectRatio, adjustCylinderLength, aromaticBonds } = props;
 
     const vRef = Vec3(), delta = Vec3();
     const pos = unit.conformation.invariantPosition;
@@ -41,9 +42,8 @@ function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Stru
     const locE = StructureElement.Location.create(structure, unit);
     const locB = Bond.Location(structure, unit, undefined, structure, unit, undefined);
 
-    if (props.includeParent) {
-        const { child } = structure;
-        if (!child) throw new Error('expected child to exist');
+    const { child } = structure;
+    if (props.includeParent && child) {
         const childUnit = child.unitMap.get(unit.id);
         if (!childUnit) throw new Error('expected childUnit to exist');
 
@@ -70,6 +70,8 @@ function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Stru
         return theme.size.size(locE) * sizeFactor;
     };
 
+    const { elementRingIndices, elementAromaticRingIndices } = unit.rings;
+
     return {
         linkCount: edgeCount * 2,
         referencePosition: (edgeIndex: number) => {
@@ -77,17 +79,28 @@ function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Stru
 
             if (aI > bI) [aI, bI] = [bI, aI];
             if (offset[aI + 1] - offset[aI] === 1) [aI, bI] = [bI, aI];
-            // TODO prefer reference atoms within rings
+
+            const aR = elementRingIndices.get(aI);
+            let maxSize = 0;
 
             for (let i = offset[aI], il = offset[aI + 1]; i < il; ++i) {
                 const _bI = b[i];
-                if (_bI !== bI && _bI !== aI) return pos(elements[_bI], vRef);
+                if (_bI !== bI && _bI !== aI) {
+                    if (aR) {
+                        const _bR = elementRingIndices.get(_bI);
+                        if (!_bR) continue;
+
+                        const size = arrayIntersectionSize(aR, _bR);
+                        if (size > maxSize) {
+                            maxSize = size;
+                            pos(elements[_bI], vRef);
+                        }
+                    } else {
+                        return pos(elements[_bI], vRef);
+                    }
+                }
             }
-            for (let i = offset[bI], il = offset[bI + 1]; i < il; ++i) {
-                const _aI = a[i];
-                if (_aI !== aI && _aI !== bI) return pos(elements[_aI], vRef);
-            }
-            return null;
+            return maxSize > 0 ? vRef : null;
         },
         position: (posA: Vec3, posB: Vec3, edgeIndex: number) => {
             pos(elements[a[edgeIndex]], posA);
@@ -111,13 +124,24 @@ function getIntraUnitBondCylinderBuilderProps(unit: Unit.Atomic, structure: Stru
             if (isBondType(f, BondType.Flag.MetallicCoordination) || isBondType(f, BondType.Flag.HydrogenBond)) {
                 // show metall coordinations and hydrogen bonds with dashed cylinders
                 return LinkStyle.Dashed;
-            } else if (o === 2) {
-                return LinkStyle.Double;
             } else if (o === 3) {
                 return LinkStyle.Triple;
-            } else {
-                return LinkStyle.Solid;
+            } else if (aromaticBonds) {
+                const aI = a[edgeIndex], bI = b[edgeIndex];
+                const aR = elementAromaticRingIndices.get(aI);
+                const bR = elementAromaticRingIndices.get(bI);
+                const arCount = (aR && bR) ? arrayIntersectionSize(aR, bR) : 0;
+
+                if (arCount || isBondType(f, BondType.Flag.Aromatic)) {
+                    if (arCount === 2) {
+                        return LinkStyle.MirroredAromatic;
+                    } else {
+                        return LinkStyle.Aromatic;
+                    }
+                }
             }
+
+            return o === 2 ? LinkStyle.Double : LinkStyle.Solid;
         },
         radius: (edgeIndex: number) => {
             return radius(edgeIndex) * sizeAspectRatio;
@@ -198,7 +222,8 @@ export function IntraUnitBondCylinderImpostorVisual(materialId: number): UnitsVi
                 newProps.stubCap !== currentProps.stubCap ||
                 !arrayEqual(newProps.includeTypes, currentProps.includeTypes) ||
                 !arrayEqual(newProps.excludeTypes, currentProps.excludeTypes) ||
-                newProps.adjustCylinderLength !== currentProps.adjustCylinderLength
+                newProps.adjustCylinderLength !== currentProps.adjustCylinderLength ||
+                newProps.aromaticBonds !== currentProps.aromaticBonds
             );
 
             const newUnit = newStructureGroup.group.units[0];
@@ -240,7 +265,8 @@ export function IntraUnitBondCylinderMeshVisual(materialId: number): UnitsVisual
                 newProps.stubCap !== currentProps.stubCap ||
                 !arrayEqual(newProps.includeTypes, currentProps.includeTypes) ||
                 !arrayEqual(newProps.excludeTypes, currentProps.excludeTypes) ||
-                newProps.adjustCylinderLength !== currentProps.adjustCylinderLength
+                newProps.adjustCylinderLength !== currentProps.adjustCylinderLength ||
+                newProps.aromaticBonds !== currentProps.aromaticBonds
             );
 
             const newUnit = newStructureGroup.group.units[0];

src/mol-repr/structure/visual/bond-intra-unit-line.ts

@@ -10,7 +10,7 @@ import { Unit, Structure, StructureElement } from '../../../mol-model/structure'
 import { Theme } from '../../../mol-theme/theme';
 import { Vec3 } from '../../../mol-math/linear-algebra';
 import { arrayEqual } from '../../../mol-util';
-import { LinkStyle, createLinkLines } from './util/link';
+import { LinkStyle, createLinkLines, LinkBuilderProps } from './util/link';
 import { UnitsVisual, UnitsLinesParams, UnitsLinesVisual, StructureGroup } from '../units-visual';
 import { VisualUpdateState } from '../../util';
 import { BondType } from '../../../mol-model/structure/model/types';
@@ -18,6 +18,7 @@ import { BondIterator, BondLineParams, getIntraBondLoci, eachIntraBond, makeIntr
 import { Sphere3D } from '../../../mol-math/geometry';
 import { Lines } from '../../../mol-geo/geometry/lines/lines';
 import { IntAdjacencyGraph } from '../../../mol-math/graph';
+import { arrayIntersectionSize } from '../../../mol-util/array';
 
 // avoiding namespace lookup improved performance in Chrome (Aug 2020)
 const isBondType = BondType.is;
@@ -29,41 +30,50 @@ function createIntraUnitBondLines(ctx: VisualContext, unit: Unit, structure: Str
     const childUnit = child?.unitMap.get(unit.id);
     if (child && !childUnit) return Lines.createEmpty(lines);
 
-    if (props.includeParent) {
-        if (!child) throw new Error('expected child to exist');
-    }
-
     const location = StructureElement.Location.create(structure, unit);
 
     const elements = unit.elements;
     const bonds = unit.bonds;
     const { edgeCount, a, b, edgeProps, offset } = bonds;
     const { order: _order, flags: _flags } = edgeProps;
-    const { sizeFactor } = props;
+    const { sizeFactor, aromaticBonds } = props;
 
     if (!edgeCount) return Lines.createEmpty(lines);
 
     const vRef = Vec3();
     const pos = unit.conformation.invariantPosition;
 
-    const builderProps = {
+    const { elementRingIndices, elementAromaticRingIndices } = unit.rings;
+
+    const builderProps: LinkBuilderProps = {
         linkCount: edgeCount * 2,
         referencePosition: (edgeIndex: number) => {
             let aI = a[edgeIndex], bI = b[edgeIndex];
 
             if (aI > bI) [aI, bI] = [bI, aI];
             if (offset[aI + 1] - offset[aI] === 1) [aI, bI] = [bI, aI];
-            // TODO prefer reference atoms within rings
+
+            const aR = elementRingIndices.get(aI);
+            let maxSize = 0;
 
             for (let i = offset[aI], il = offset[aI + 1]; i < il; ++i) {
                 const _bI = b[i];
-                if (_bI !== bI && _bI !== aI) return pos(elements[_bI], vRef);
+                if (_bI !== bI && _bI !== aI) {
+                    if (aR) {
+                        const _bR = elementRingIndices.get(_bI);
+                        if (!_bR) continue;
+
+                        const size = arrayIntersectionSize(aR, _bR);
+                        if (size > maxSize) {
+                            maxSize = size;
+                            pos(elements[_bI], vRef);
+                        }
+                    } else {
+                        return pos(elements[_bI], vRef);
+                    }
+                }
             }
-            for (let i = offset[bI], il = offset[bI + 1]; i < il; ++i) {
-                const _aI = a[i];
-                if (_aI !== aI && _aI !== bI) return pos(elements[_aI], vRef);
-            }
-            return null;
+            return maxSize > 0 ? vRef : null;
         },
         position: (posA: Vec3, posB: Vec3, edgeIndex: number) => {
             pos(elements[a[edgeIndex]], posA);
@@ -75,13 +85,24 @@ function createIntraUnitBondLines(ctx: VisualContext, unit: Unit, structure: Str
             if (isBondType(f, BondType.Flag.MetallicCoordination) || isBondType(f, BondType.Flag.HydrogenBond)) {
                 // show metall coordinations and hydrogen bonds with dashed cylinders
                 return LinkStyle.Dashed;
-            } else if (o === 2) {
-                return LinkStyle.Double;
             } else if (o === 3) {
                 return LinkStyle.Triple;
-            } else {
-                return LinkStyle.Solid;
+            } else if (aromaticBonds) {
+                const aI = a[edgeIndex], bI = b[edgeIndex];
+                const aR = elementAromaticRingIndices.get(aI);
+                const bR = elementAromaticRingIndices.get(bI);
+                const arCount = (aR && bR) ? arrayIntersectionSize(aR, bR) : 0;
+
+                if (arCount || isBondType(f, BondType.Flag.Aromatic)) {
+                    if (arCount === 2) {
+                        return LinkStyle.MirroredAromatic;
+                    } else {
+                        return LinkStyle.Aromatic;
+                    }
+                }
             }
+
+            return o === 2 ? LinkStyle.Double : LinkStyle.Solid;
         },
         radius: (edgeIndex: number) => {
             location.element = elements[a[edgeIndex]];
@@ -123,7 +144,8 @@ export function IntraUnitBondLineVisual(materialId: number): UnitsVisual<IntraUn
                 newProps.dashCount !== currentProps.dashCount ||
                 newProps.ignoreHydrogens !== currentProps.ignoreHydrogens ||
                 !arrayEqual(newProps.includeTypes, currentProps.includeTypes) ||
-                !arrayEqual(newProps.excludeTypes, currentProps.excludeTypes)
+                !arrayEqual(newProps.excludeTypes, currentProps.excludeTypes) ||
+                newProps.aromaticBonds !== currentProps.aromaticBonds
             );
 
             const newUnit = newStructureGroup.group.units[0];

src/mol-repr/structure/visual/polymer-backbone-cylinder.ts

@@ -1,34 +1,102 @@
 /**
- * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
 
 import { ParamDefinition as PD } from '../../../mol-util/param-definition';
 import { VisualContext } from '../../visual';
-import { Unit, Structure } from '../../../mol-model/structure';
+import { Unit, Structure, StructureElement, ElementIndex } from '../../../mol-model/structure';
 import { Theme } from '../../../mol-theme/theme';
 import { Mesh } from '../../../mol-geo/geometry/mesh/mesh';
 import { MeshBuilder } from '../../../mol-geo/geometry/mesh/mesh-builder';
 import { Vec3 } from '../../../mol-math/linear-algebra';
 import { CylinderProps } from '../../../mol-geo/primitive/cylinder';
-import { PolymerBackboneIterator } from './util/polymer';
-import { OrderedSet } from '../../../mol-data/int';
+import { eachPolymerElement, getPolymerElementLoci, NucleicShift, PolymerLocationIterator, StandardShift } from './util/polymer';
 import { addCylinder } from '../../../mol-geo/geometry/mesh/builder/cylinder';
-import { UnitsMeshParams, UnitsVisual, UnitsMeshVisual } from '../units-visual';
-import { ElementIterator, getElementLoci, eachElement } from './util/element';
+import { UnitsMeshParams, UnitsVisual, UnitsMeshVisual, UnitsCylindersVisual, UnitsCylindersParams, StructureGroup } from '../units-visual';
 import { VisualUpdateState } from '../../util';
 import { BaseGeometry } from '../../../mol-geo/geometry/base';
 import { Sphere3D } from '../../../mol-math/geometry';
+import { isNucleic, MoleculeType } from '../../../mol-model/structure/model/types';
+import { WebGLContext } from '../../../mol-gl/webgl/context';
+import { Cylinders } from '../../../mol-geo/geometry/cylinders/cylinders';
+import { CylindersBuilder } from '../../../mol-geo/geometry/cylinders/cylinders-builder';
+import { eachPolymerBackboneLink } from './util/polymer/backbone';
+
+// avoiding namespace lookup improved performance in Chrome (Aug 2020)
+const v3scale = Vec3.scale;
+const v3add = Vec3.add;
+const v3sub = Vec3.sub;
 
 export const PolymerBackboneCylinderParams = {
+    ...UnitsMeshParams,
+    ...UnitsCylindersParams,
     sizeFactor: PD.Numeric(0.3, { min: 0, max: 10, step: 0.01 }),
     radialSegments: PD.Numeric(16, { min: 2, max: 56, step: 2 }, BaseGeometry.CustomQualityParamInfo),
+    tryUseImpostor: PD.Boolean(true),
 };
-export const DefaultPolymerBackboneCylinderProps = PD.getDefaultValues(PolymerBackboneCylinderParams);
-export type PolymerBackboneCylinderProps = typeof DefaultPolymerBackboneCylinderProps
+export type PolymerBackboneCylinderParams = typeof PolymerBackboneCylinderParams
+
+export function PolymerBackboneCylinderVisual(materialId: number, structure: Structure, props: PD.Values<PolymerBackboneCylinderParams>, webgl?: WebGLContext) {
+    return props.tryUseImpostor && webgl && webgl.extensions.fragDepth
+        ? PolymerBackboneCylinderImpostorVisual(materialId)
+        : PolymerBackboneCylinderMeshVisual(materialId);
+}
+
+interface PolymerBackboneCylinderProps {
+    radialSegments: number,
+    sizeFactor: number,
+}
+
+function createPolymerBackboneCylinderImpostor(ctx: VisualContext, unit: Unit, structure: Structure, theme: Theme, props: PolymerBackboneCylinderProps, cylinders?: Cylinders) {
+    const polymerElementCount = unit.polymerElements.length;
+    if (!polymerElementCount) return Cylinders.createEmpty(cylinders);
+
+    const cylindersCountEstimate = polymerElementCount * 2;
+    const builder = CylindersBuilder.create(cylindersCountEstimate, cylindersCountEstimate / 4, cylinders);
+
+    const pos = unit.conformation.invariantPosition;
+    const pA = Vec3();
+    const pB = Vec3();
+    const pM = Vec3();
+
+    const add = function(indexA: ElementIndex, indexB: ElementIndex, groupA: number, groupB: number, moleculeType: MoleculeType) {
+        pos(indexA, pA);
+        pos(indexB, pB);
+
+        const isNucleicType = isNucleic(moleculeType);
+        const shift = isNucleicType ? NucleicShift : StandardShift;
+
+        v3add(pM, pA, v3scale(pM, v3sub(pM, pB, pA), shift));
+        builder.add(pA[0], pA[1], pA[2], pM[0], pM[1], pM[2], 1, false, false, groupA);
+        builder.add(pM[0], pM[1], pM[2], pB[0], pB[1], pB[2], 1, false, false, groupB);
+    };
+
+    eachPolymerBackboneLink(unit, add);
+
+    const c = builder.getCylinders();
+
+    const sphere = Sphere3D.expand(Sphere3D(), unit.boundary.sphere, 1 * props.sizeFactor);
+    c.setBoundingSphere(sphere);
+
+    return c;
+}
+
+export function PolymerBackboneCylinderImpostorVisual(materialId: number): UnitsVisual<PolymerBackboneCylinderParams> {
+    return UnitsCylindersVisual<PolymerBackboneCylinderParams>({
+        defaultProps: PD.getDefaultValues(PolymerBackboneCylinderParams),
+        createGeometry: createPolymerBackboneCylinderImpostor,
+        createLocationIterator: PolymerLocationIterator.fromGroup,
+        getLoci: getPolymerElementLoci,
+        eachLocation: eachPolymerElement,
+        setUpdateState: (state: VisualUpdateState, newProps: PD.Values<PolymerBackboneCylinderParams>, currentProps: PD.Values<PolymerBackboneCylinderParams>) => { },
+        mustRecreate: (structureGroup: StructureGroup, props: PD.Values<PolymerBackboneCylinderParams>, webgl?: WebGLContext) => {
+            return !props.tryUseImpostor || !webgl;
+        }
+    }, materialId);
+}
 
-// TODO do group id based on polymer index not element index
 function createPolymerBackboneCylinderMesh(ctx: VisualContext, unit: Unit, structure: Structure, theme: Theme, props: PolymerBackboneCylinderProps, mesh?: Mesh) {
     const polymerElementCount = unit.polymerElements.length;
     if (!polymerElementCount) return Mesh.createEmpty(mesh);
@@ -38,26 +106,34 @@ function createPolymerBackboneCylinderMesh(ctx: VisualContext, unit: Unit, struc
     const vertexCountEstimate = radialSegments * 2 * polymerElementCount * 2;
     const builderState = MeshBuilder.createState(vertexCountEstimate, vertexCountEstimate / 10, mesh);
 
-    const { elements } = unit;
     const pos = unit.conformation.invariantPosition;
-    const pA = Vec3.zero();
-    const pB = Vec3.zero();
+    const pA = Vec3();
+    const pB = Vec3();
     const cylinderProps: CylinderProps = { radiusTop: 1, radiusBottom: 1, radialSegments };
 
-    const polymerBackboneIt = PolymerBackboneIterator(structure, unit);
-    while (polymerBackboneIt.hasNext) {
-        const { centerA, centerB } = polymerBackboneIt.move();
+    const centerA = StructureElement.Location.create(structure, unit);
+    const centerB = StructureElement.Location.create(structure, unit);
+
+    const add = function(indexA: ElementIndex, indexB: ElementIndex, groupA: number, groupB: number, moleculeType: MoleculeType) {
+        centerA.element = indexA;
+        centerB.element = indexB;
+
         pos(centerA.element, pA);
         pos(centerB.element, pB);
 
+        const isNucleicType = isNucleic(moleculeType);
+        const shift = isNucleicType ? NucleicShift : StandardShift;
+
         cylinderProps.radiusTop = cylinderProps.radiusBottom = theme.size.size(centerA) * sizeFactor;
-        builderState.currentGroup = OrderedSet.indexOf(elements, centerA.element);
-        addCylinder(builderState, pA, pB, 0.5, cylinderProps);
+        builderState.currentGroup = groupA;
+        addCylinder(builderState, pA, pB, shift, cylinderProps);
 
         cylinderProps.radiusTop = cylinderProps.radiusBottom = theme.size.size(centerB) * sizeFactor;
-        builderState.currentGroup = OrderedSet.indexOf(elements, centerB.element);
-        addCylinder(builderState, pB, pA, 0.5, cylinderProps);
-    }
+        builderState.currentGroup = groupB;
+        addCylinder(builderState, pB, pA, 1 - shift, cylinderProps);
+    };
+
+    eachPolymerBackboneLink(unit, add);
 
     const m = MeshBuilder.getMesh(builderState);
 
@@ -67,25 +143,21 @@ function createPolymerBackboneCylinderMesh(ctx: VisualContext, unit: Unit, struc
     return m;
 }
 
-export const PolymerBackboneParams = {
-    ...UnitsMeshParams,
-    ...PolymerBackboneCylinderParams,
-};
-export type PolymerBackboneParams = typeof PolymerBackboneParams
-
-export function PolymerBackboneVisual(materialId: number): UnitsVisual<PolymerBackboneParams> {
-    return UnitsMeshVisual<PolymerBackboneParams>({
-        defaultProps: PD.getDefaultValues(PolymerBackboneParams),
+export function PolymerBackboneCylinderMeshVisual(materialId: number): UnitsVisual<PolymerBackboneCylinderParams> {
+    return UnitsMeshVisual<PolymerBackboneCylinderParams>({
+        defaultProps: PD.getDefaultValues(PolymerBackboneCylinderParams),
         createGeometry: createPolymerBackboneCylinderMesh,
-        // TODO create a specialized location iterator
-        createLocationIterator: ElementIterator.fromGroup,
-        getLoci: getElementLoci,
-        eachLocation: eachElement,
-        setUpdateState: (state: VisualUpdateState, newProps: PD.Values<PolymerBackboneParams>, currentProps: PD.Values<PolymerBackboneParams>) => {
+        createLocationIterator: PolymerLocationIterator.fromGroup,
+        getLoci: getPolymerElementLoci,
+        eachLocation: eachPolymerElement,
+        setUpdateState: (state: VisualUpdateState, newProps: PD.Values<PolymerBackboneCylinderParams>, currentProps: PD.Values<PolymerBackboneCylinderParams>) => {
             state.createGeometry = (
                 newProps.sizeFactor !== currentProps.sizeFactor ||
                 newProps.radialSegments !== currentProps.radialSegments
             );
+        },
+        mustRecreate: (structureGroup: StructureGroup, props: PD.Values<PolymerBackboneCylinderParams>, webgl?: WebGLContext) => {
+            return props.tryUseImpostor && !!webgl;
         }
     }, materialId);
 }

src/mol-repr/structure/visual/polymer-backbone-sphere.ts

@@ -1 +1,131 @@
-// TODO
+/**
+ * Copyright (c) 2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+
+import { ParamDefinition as PD } from '../../../mol-util/param-definition';
+import { VisualContext } from '../../visual';
+import { Unit, Structure, ElementIndex, StructureElement } from '../../../mol-model/structure';
+import { Theme } from '../../../mol-theme/theme';
+import { Mesh } from '../../../mol-geo/geometry/mesh/mesh';
+import { MeshBuilder } from '../../../mol-geo/geometry/mesh/mesh-builder';
+import { Vec3 } from '../../../mol-math/linear-algebra';
+import { eachPolymerElement, getPolymerElementLoci, PolymerLocationIterator } from './util/polymer';
+import { UnitsMeshParams, UnitsVisual, UnitsMeshVisual, UnitsSpheresVisual, UnitsSpheresParams, StructureGroup } from '../units-visual';
+import { VisualUpdateState } from '../../util';
+import { BaseGeometry } from '../../../mol-geo/geometry/base';
+import { Sphere3D } from '../../../mol-math/geometry';
+import { addSphere } from '../../../mol-geo/geometry/mesh/builder/sphere';
+import { sphereVertexCount } from '../../../mol-geo/primitive/sphere';
+import { WebGLContext } from '../../../mol-gl/webgl/context';
+import { Spheres } from '../../../mol-geo/geometry/spheres/spheres';
+import { SpheresBuilder } from '../../../mol-geo/geometry/spheres/spheres-builder';
+import { eachPolymerBackboneElement } from './util/polymer/backbone';
+
+export const PolymerBackboneSphereParams = {
+    ...UnitsMeshParams,
+    ...UnitsSpheresParams,
+    sizeFactor: PD.Numeric(0.3, { min: 0, max: 10, step: 0.01 }),
+    detail: PD.Numeric(0, { min: 0, max: 3, step: 1 }, BaseGeometry.CustomQualityParamInfo),
+    tryUseImpostor: PD.Boolean(true),
+};
+export type PolymerBackboneSphereParams = typeof PolymerBackboneSphereParams
+
+export function PolymerBackboneSphereVisual(materialId: number, structure: Structure, props: PD.Values<PolymerBackboneSphereParams>, webgl?: WebGLContext) {
+    return props.tryUseImpostor && webgl && webgl.extensions.fragDepth
+        ? PolymerBackboneSphereImpostorVisual(materialId)
+        : PolymerBackboneSphereMeshVisual(materialId);
+}
+
+interface PolymerBackboneSphereProps {
+    detail: number,
+    sizeFactor: number,
+}
+
+function createPolymerBackboneSphereImpostor(ctx: VisualContext, unit: Unit, structure: Structure, theme: Theme, props: PolymerBackboneSphereProps, spheres?: Spheres) {
+    const polymerElementCount = unit.polymerElements.length;
+    if (!polymerElementCount) return Spheres.createEmpty(spheres);
+
+    const builder = SpheresBuilder.create(polymerElementCount, polymerElementCount / 2, spheres);
+
+    const pos = unit.conformation.invariantPosition;
+    const p = Vec3();
+
+    const add = (index: ElementIndex, group: number) => {
+        pos(index, p);
+        builder.add(p[0], p[1], p[2], group);
+    };
+
+    eachPolymerBackboneElement(unit, add);
+
+    const s = builder.getSpheres();
+
+    const sphere = Sphere3D.expand(Sphere3D(), unit.boundary.sphere, 1 * props.sizeFactor);
+    s.setBoundingSphere(sphere);
+
+    return s;
+}
+
+export function PolymerBackboneSphereImpostorVisual(materialId: number): UnitsVisual<PolymerBackboneSphereParams> {
+    return UnitsSpheresVisual<PolymerBackboneSphereParams>({
+        defaultProps: PD.getDefaultValues(PolymerBackboneSphereParams),
+        createGeometry: createPolymerBackboneSphereImpostor,
+        createLocationIterator: PolymerLocationIterator.fromGroup,
+        getLoci: getPolymerElementLoci,
+        eachLocation: eachPolymerElement,
+        setUpdateState: (state: VisualUpdateState, newProps: PD.Values<PolymerBackboneSphereParams>, currentProps: PD.Values<PolymerBackboneSphereParams>) => { },
+        mustRecreate: (structureGroup: StructureGroup, props: PD.Values<PolymerBackboneSphereParams>, webgl?: WebGLContext) => {
+            return !props.tryUseImpostor || !webgl;
+        }
+    }, materialId);
+}
+
+function createPolymerBackboneSphereMesh(ctx: VisualContext, unit: Unit, structure: Structure, theme: Theme, props: PolymerBackboneSphereProps, mesh?: Mesh) {
+    const polymerElementCount = unit.polymerElements.length;
+    if (!polymerElementCount) return Mesh.createEmpty(mesh);
+
+    const { detail, sizeFactor } = props;
+
+    const vertexCount = polymerElementCount * sphereVertexCount(detail);
+    const builderState = MeshBuilder.createState(vertexCount, vertexCount / 2, mesh);
+
+    const pos = unit.conformation.invariantPosition;
+    const p = Vec3();
+    const center = StructureElement.Location.create(structure, unit);
+
+    const add = (index: ElementIndex, group: number) => {
+        center.element = index;
+        pos(center.element, p);
+        builderState.currentGroup = group;
+        addSphere(builderState, p, theme.size.size(center) * sizeFactor, detail);
+    };
+
+    eachPolymerBackboneElement(unit, add);
+
+    const m = MeshBuilder.getMesh(builderState);
+
+    const sphere = Sphere3D.expand(Sphere3D(), unit.boundary.sphere, 1 * props.sizeFactor);
+    m.setBoundingSphere(sphere);
+
+    return m;
+}
+
+export function PolymerBackboneSphereMeshVisual(materialId: number): UnitsVisual<PolymerBackboneSphereParams> {
+    return UnitsMeshVisual<PolymerBackboneSphereParams>({
+        defaultProps: PD.getDefaultValues(PolymerBackboneSphereParams),
+        createGeometry: createPolymerBackboneSphereMesh,
+        createLocationIterator: PolymerLocationIterator.fromGroup,
+        getLoci: getPolymerElementLoci,
+        eachLocation: eachPolymerElement,
+        setUpdateState: (state: VisualUpdateState, newProps: PD.Values<PolymerBackboneSphereParams>, currentProps: PD.Values<PolymerBackboneSphereParams>) => {
+            state.createGeometry = (
+                newProps.sizeFactor !== currentProps.sizeFactor ||
+                newProps.detail !== currentProps.detail
+            );
+        },
+        mustRecreate: (structureGroup: StructureGroup, props: PD.Values<PolymerBackboneSphereParams>, webgl?: WebGLContext) => {
+            return props.tryUseImpostor && !!webgl;
+        }
+    }, materialId);
+}

src/mol-repr/structure/visual/util/bond.ts

@@ -20,6 +20,7 @@ export const BondParams = {
     includeTypes: PD.MultiSelect(ObjectKeys(BondType.Names), PD.objectToOptions(BondType.Names)),
     excludeTypes: PD.MultiSelect([] as BondType.Names[], PD.objectToOptions(BondType.Names)),
     ignoreHydrogens: PD.Boolean(false),
+    aromaticBonds: PD.Boolean(false, { description: 'Display aromatic bonds with dashes' }),
 };
 export const DefaultBondProps = PD.getDefaultValues(BondParams);
 export type BondProps = typeof DefaultBondProps

src/mol-repr/structure/visual/util/element.ts

@@ -46,7 +46,7 @@ export function makeElementIgnoreTest(structure: Structure, unit: Unit, props: E
     const childUnit = child?.unitMap.get(unit.id);
     if (child && !childUnit) throw new Error('expected childUnit to exist if child exists');
 
-    if (!child && ((!ignoreHydrogens && !traceOnly) || traceOnly)) return;
+    if (!child && !ignoreHydrogens && !traceOnly) return;
 
     return (element: ElementIndex) => {
         return (

src/mol-repr/structure/visual/util/link.ts

@@ -18,7 +18,7 @@ import { Cylinders } from '../../../../mol-geo/geometry/cylinders/cylinders';
 import { CylindersBuilder } from '../../../../mol-geo/geometry/cylinders/cylinders-builder';
 
 export const LinkCylinderParams = {
-    linkScale: PD.Numeric(0.4, { min: 0, max: 1, step: 0.1 }),
+    linkScale: PD.Numeric(0.45, { min: 0, max: 1, step: 0.01 }),
     linkSpacing: PD.Numeric(1, { min: 0, max: 2, step: 0.01 }),
     linkCap: PD.Boolean(false),
     dashCount: PD.Numeric(4, { min: 2, max: 10, step: 2 }),
@@ -84,7 +84,9 @@ export const enum LinkStyle {
     Dashed = 1,
     Double = 2,
     Triple = 3,
-    Disk = 4
+    Disk = 4,
+    Aromatic = 5,
+    MirroredAromatic = 6,
 }
 
 // avoiding namespace lookup improved performance in Chrome (Aug 2020)
@@ -133,6 +135,8 @@ export function createLinkCylinderMesh(ctx: VisualContext, linkBuilder: LinkBuil
         const [topCap, bottomCap] = (v3dot(tmpV12, up) > 0) ? [linkStub, linkCap] : [linkCap, linkStub];
         builderState.currentGroup = edgeIndex;
 
+        const aromaticOffsetFactor = 4.5;
+
         if (linkStyle === LinkStyle.Solid) {
             cylinderProps.radiusTop = cylinderProps.radiusBottom = linkRadius;
             cylinderProps.topCap = topCap;
@@ -144,20 +148,41 @@ export function createLinkCylinderMesh(ctx: VisualContext, linkBuilder: LinkBuil
             cylinderProps.topCap = cylinderProps.bottomCap = dashCap;
 
             addFixedCountDashedCylinder(builderState, va, vb, 0.5, segmentCount, cylinderProps);
-        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple) {
-            const order = linkStyle === LinkStyle.Double ? 2 : 3;
+        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple || linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+            const order = linkStyle === LinkStyle.Double ? 2 :
+                linkStyle === LinkStyle.Triple ? 3 : 1.5;
             const multiRadius = linkRadius * (linkScale / (0.5 * order));
             const absOffset = (linkRadius - multiRadius) * linkSpacing;
 
             calculateShiftDir(vShift, va, vb, referencePosition ? referencePosition(edgeIndex) : null);
-            v3setMagnitude(vShift, vShift, absOffset);
 
-            cylinderProps.radiusTop = cylinderProps.radiusBottom = multiRadius;
             cylinderProps.topCap = topCap;
             cylinderProps.bottomCap = bottomCap;
 
-            if (order === 3) addCylinder(builderState, va, vb, 0.5, cylinderProps);
-            addDoubleCylinder(builderState, va, vb, 0.5, vShift, cylinderProps);
+            if (linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+                cylinderProps.radiusTop = cylinderProps.radiusBottom = linkRadius;
+                addCylinder(builderState, va, vb, 0.5, cylinderProps);
+
+                cylinderProps.radiusTop = cylinderProps.radiusBottom = linkRadius * linkScale;
+                cylinderProps.topCap = cylinderProps.bottomCap = dashCap;
+                v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor);
+                v3sub(va, va, vShift);
+                v3sub(vb, vb, vShift);
+                addFixedCountDashedCylinder(builderState, va, vb, 0.5, 3, cylinderProps);
+
+                if (linkStyle === LinkStyle.MirroredAromatic) {
+                    v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor * 2);
+                    v3add(va, va, vShift);
+                    v3add(vb, vb, vShift);
+                    addFixedCountDashedCylinder(builderState, va, vb, 0.5, 3, cylinderProps);
+                }
+            } else {
+                v3setMagnitude(vShift, vShift, absOffset);
+
+                cylinderProps.radiusTop = cylinderProps.radiusBottom = multiRadius;
+                if (order === 3) addCylinder(builderState, va, vb, 0.5, cylinderProps);
+                addDoubleCylinder(builderState, va, vb, 0.5, vShift, cylinderProps);
+            }
         } else if (linkStyle === LinkStyle.Disk) {
             v3scale(tmpV12, tmpV12, 0.475);
             v3add(va, va, tmpV12);
@@ -190,12 +215,17 @@ export function createLinkCylinderImpostors(ctx: VisualContext, linkBuilder: Lin
 
     const va = Vec3();
     const vb = Vec3();
+    const vm = Vec3();
     const vShift = Vec3();
 
     // automatically adjust length for evenly spaced dashed cylinders
     const segmentCount = dashCount % 2 === 1 ? dashCount : dashCount + 1;
     const lengthScale = 0.5 - (0.5 / 2 / segmentCount);
 
+    const aromaticSegmentCount = 3;
+    const aromaticLengthScale = 0.5 - (0.5 / 2 / aromaticSegmentCount);
+    const aromaticOffsetFactor = 4.5;
+
     for (let edgeIndex = 0, _eI = linkCount; edgeIndex < _eI; ++edgeIndex) {
         if (ignore && ignore(edgeIndex)) continue;
 
@@ -206,24 +236,45 @@ export function createLinkCylinderImpostors(ctx: VisualContext, linkBuilder: Lin
         const linkStub = stubCap && (stub ? stub(edgeIndex) : false);
 
         if (linkStyle === LinkStyle.Solid) {
-            v3scale(vb, v3add(vb, va, vb), 0.5);
-            builder.add(va[0], va[1], va[2], vb[0], vb[1], vb[2], 1, linkCap, linkStub, edgeIndex);
+            v3scale(vm, v3add(vm, va, vb), 0.5);
+            builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], 1, linkCap, linkStub, edgeIndex);
         } else if (linkStyle === LinkStyle.Dashed) {
             v3scale(tmpV12, v3sub(tmpV12, vb, va), lengthScale);
             v3sub(vb, vb, tmpV12);
             builder.addFixedCountDashes(va, vb, segmentCount, dashScale, dashCap, dashCap, edgeIndex);
-        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple) {
-            v3scale(vb, v3add(vb, va, vb), 0.5);
-            const order = linkStyle === LinkStyle.Double ? 2 : 3;
+        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple || linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+            const order = linkStyle === LinkStyle.Double ? 2 :
+                linkStyle === LinkStyle.Triple ? 3 : 1.5;
             const multiScale = linkScale / (0.5 * order);
             const absOffset = (linkRadius - multiScale * linkRadius) * linkSpacing;
 
+            v3scale(vm, v3add(vm, va, vb), 0.5);
             calculateShiftDir(vShift, va, vb, referencePosition ? referencePosition(edgeIndex) : null);
-            v3setMagnitude(vShift, vShift, absOffset);
 
-            if (order === 3) builder.add(va[0], va[1], va[2], vb[0], vb[1], vb[2], multiScale, linkCap, false, edgeIndex);
-            builder.add(va[0] + vShift[0], va[1] + vShift[1], va[2] + vShift[2], vb[0] + vShift[0], vb[1] + vShift[1], vb[2] + vShift[2], multiScale, linkCap, linkStub, edgeIndex);
-            builder.add(va[0] - vShift[0], va[1] - vShift[1], va[2] - vShift[2], vb[0] - vShift[0], vb[1] - vShift[1], vb[2] - vShift[2], multiScale, linkCap, linkStub, edgeIndex);
+            if (linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+                builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], 1, linkCap, linkStub, edgeIndex);
+
+                v3scale(tmpV12, v3sub(tmpV12, vb, va), aromaticLengthScale);
+                v3sub(vb, vb, tmpV12);
+
+                v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor);
+                v3sub(va, va, vShift);
+                v3sub(vb, vb, vShift);
+                builder.addFixedCountDashes(va, vb, aromaticSegmentCount, linkScale, dashCap, dashCap, edgeIndex);
+
+                if (linkStyle === LinkStyle.MirroredAromatic) {
+                    v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor * 2);
+                    v3add(va, va, vShift);
+                    v3add(vb, vb, vShift);
+                    builder.addFixedCountDashes(va, vb, aromaticSegmentCount, linkScale, dashCap, dashCap, edgeIndex);
+                }
+            } else {
+                v3setMagnitude(vShift, vShift, absOffset);
+
+                if (order === 3) builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], multiScale, linkCap, false, edgeIndex);
+                builder.add(va[0] + vShift[0], va[1] + vShift[1], va[2] + vShift[2], vm[0] + vShift[0], vm[1] + vShift[1], vm[2] + vShift[2], multiScale, linkCap, linkStub, edgeIndex);
+                builder.add(va[0] - vShift[0], va[1] - vShift[1], va[2] - vShift[2], vm[0] - vShift[0], vm[1] - vShift[1], vm[2] - vShift[2], multiScale, linkCap, linkStub, edgeIndex);
+            }
         } else if (linkStyle === LinkStyle.Disk) {
             v3scale(tmpV12, v3sub(tmpV12, vb, va), 0.475);
             v3add(va, va, tmpV12);
@@ -252,12 +303,17 @@ export function createLinkLines(ctx: VisualContext, linkBuilder: LinkBuilderProp
 
     const va = Vec3();
     const vb = Vec3();
+    const vm = Vec3();
     const vShift = Vec3();
 
     // automatically adjust length for evenly spaced dashed lines
     const segmentCount = dashCount % 2 === 1 ? dashCount : dashCount + 1;
     const lengthScale = 0.5 - (0.5 / 2 / segmentCount);
 
+    const aromaticSegmentCount = 3;
+    const aromaticLengthScale = 0.5 - (0.5 / 2 / aromaticSegmentCount);
+    const aromaticOffsetFactor = 4.5;
+
     for (let edgeIndex = 0, _eI = linkCount; edgeIndex < _eI; ++edgeIndex) {
         if (ignore && ignore(edgeIndex)) continue;
 
@@ -266,24 +322,45 @@ export function createLinkLines(ctx: VisualContext, linkBuilder: LinkBuilderProp
         const linkStyle = style ? style(edgeIndex) : LinkStyle.Solid;
 
         if (linkStyle === LinkStyle.Solid) {
-            v3scale(vb, v3add(vb, va, vb), 0.5);
-            builder.add(va[0], va[1], va[2], vb[0], vb[1], vb[2], edgeIndex);
+            v3scale(vm, v3add(vm, va, vb), 0.5);
+            builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], edgeIndex);
         } else if (linkStyle === LinkStyle.Dashed) {
             v3scale(tmpV12, v3sub(tmpV12, vb, va), lengthScale);
             v3sub(vb, vb, tmpV12);
             builder.addFixedCountDashes(va, vb, segmentCount, edgeIndex);
-        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple) {
-            v3scale(vb, v3add(vb, va, vb), 0.5);
-            const order = linkStyle === LinkStyle.Double ? 2 : 3;
+        } else if (linkStyle === LinkStyle.Double || linkStyle === LinkStyle.Triple || linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+            const order = linkStyle === LinkStyle.Double ? 2 :
+                linkStyle === LinkStyle.Triple ? 3 : 1.5;
             const multiRadius = 1 * (linkScale / (0.5 * order));
             const absOffset = (1 - multiRadius) * linkSpacing;
 
+            v3scale(vm, v3add(vm, va, vb), 0.5);
             calculateShiftDir(vShift, va, vb, referencePosition ? referencePosition(edgeIndex) : null);
-            v3setMagnitude(vShift, vShift, absOffset);
 
-            if (order === 3) builder.add(va[0], va[1], va[2], vb[0], vb[1], vb[2], edgeIndex);
-            builder.add(va[0] + vShift[0], va[1] + vShift[1], va[2] + vShift[2], vb[0] + vShift[0], vb[1] + vShift[1], vb[2] + vShift[2], edgeIndex);
-            builder.add(va[0] - vShift[0], va[1] - vShift[1], va[2] - vShift[2], vb[0] - vShift[0], vb[1] - vShift[1], vb[2] - vShift[2], edgeIndex);
+            if (linkStyle === LinkStyle.Aromatic || linkStyle === LinkStyle.MirroredAromatic) {
+                builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], edgeIndex);
+
+                v3scale(tmpV12, v3sub(tmpV12, vb, va), aromaticLengthScale);
+                v3sub(vb, vb, tmpV12);
+
+                v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor);
+                v3sub(va, va, vShift);
+                v3sub(vb, vb, vShift);
+                builder.addFixedCountDashes(va, vb, aromaticSegmentCount, edgeIndex);
+
+                if (linkStyle === LinkStyle.MirroredAromatic) {
+                    v3setMagnitude(vShift, vShift, absOffset * aromaticOffsetFactor * 2);
+                    v3add(va, va, vShift);
+                    v3add(vb, vb, vShift);
+                    builder.addFixedCountDashes(va, vb, aromaticSegmentCount, edgeIndex);
+                }
+            } else {
+                v3setMagnitude(vShift, vShift, absOffset);
+
+                if (order === 3) builder.add(va[0], va[1], va[2], vm[0], vm[1], vm[2], edgeIndex);
+                builder.add(va[0] + vShift[0], va[1] + vShift[1], va[2] + vShift[2], vm[0] + vShift[0], vm[1] + vShift[1], vm[2] + vShift[2], edgeIndex);
+                builder.add(va[0] - vShift[0], va[1] - vShift[1], va[2] - vShift[2], vm[0] - vShift[0], vm[1] - vShift[1], vm[2] - vShift[2], edgeIndex);
+            }
         } else if (linkStyle === LinkStyle.Disk) {
             v3scale(tmpV12, v3sub(tmpV12, vb, va), 0.475);
             v3add(va, va, tmpV12);

src/mol-repr/structure/visual/util/polymer.ts

@@ -14,7 +14,7 @@ import { PickingId } from '../../../../mol-geo/geometry/picking';
 import { StructureGroup } from '../../../structure/units-visual';
 import { getResidueLoci } from './common';
 
-export * from './polymer/backbone-iterator';
+export * from './polymer/backbone';
 export * from './polymer/gap-iterator';
 export * from './polymer/trace-iterator';
 export * from './polymer/curve-segment';

src/mol-repr/structure/visual/util/polymer/backbone-iterator.ts

@@ -1,134 +0,0 @@
-/**
- * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
- *
- * @author Alexander Rose <alexander.rose@weirdbyte.de>
- */
-
-import { Unit, Structure, StructureElement, ElementIndex, ResidueIndex } from '../../../../../mol-model/structure';
-import { Segmentation } from '../../../../../mol-data/int';
-import { Iterator } from '../../../../../mol-data/iterator';
-import { SortedRanges } from '../../../../../mol-data/int/sorted-ranges';
-import { getPolymerRanges } from '../polymer';
-
-/** Iterates over consecutive pairs of residues/coarse elements in polymers */
-export function PolymerBackboneIterator(structure: Structure, unit: Unit): Iterator<PolymerBackbonePair> {
-    switch (unit.kind) {
-        case Unit.Kind.Atomic: return new AtomicPolymerBackboneIterator(structure, unit);
-        case Unit.Kind.Spheres:
-        case Unit.Kind.Gaussians:
-            return new CoarsePolymerBackboneIterator(structure, unit);
-    }
-}
-
-interface PolymerBackbonePair {
-    centerA: StructureElement.Location
-    centerB: StructureElement.Location
-}
-
-function createPolymerBackbonePair (structure: Structure, unit: Unit) {
-    return {
-        centerA: StructureElement.Location.create(structure, unit),
-        centerB: StructureElement.Location.create(structure, unit),
-    };
-}
-
-const enum AtomicPolymerBackboneIteratorState { nextPolymer, firstResidue, nextResidue, cycle }
-
-export class AtomicPolymerBackboneIterator implements Iterator<PolymerBackbonePair> {
-    private traceElementIndex: ArrayLike<ElementIndex>
-    private value: PolymerBackbonePair
-    private polymerIt: SortedRanges.Iterator<ElementIndex, ResidueIndex>
-    private residueIt: Segmentation.SegmentIterator<ResidueIndex>
-    private state: AtomicPolymerBackboneIteratorState = AtomicPolymerBackboneIteratorState.nextPolymer
-    private residueSegment: Segmentation.Segment<ResidueIndex>
-    hasNext: boolean = false;
-
-    move() {
-        if (this.state === AtomicPolymerBackboneIteratorState.nextPolymer) {
-            while (this.polymerIt.hasNext) {
-                this.residueIt.setSegment(this.polymerIt.move());
-                if (this.residueIt.hasNext) {
-                    this.residueSegment = this.residueIt.move();
-                    this.value.centerB.element = this.traceElementIndex[this.residueSegment.index];
-                    this.state = AtomicPolymerBackboneIteratorState.nextResidue;
-                    break;
-                }
-            }
-        }
-
-        if (this.state === AtomicPolymerBackboneIteratorState.nextResidue) {
-            this.residueSegment = this.residueIt.move();
-            this.value.centerA.element = this.value.centerB.element;
-            this.value.centerB.element = this.traceElementIndex[this.residueSegment.index];
-            if (!this.residueIt.hasNext) {
-                if (this.unit.model.atomicRanges.cyclicPolymerMap.has(this.residueSegment.index)) {
-                    this.state = AtomicPolymerBackboneIteratorState.cycle;
-                } else {
-                    // TODO need to advance to a polymer that has two or more residues (can't assume it has)
-                    this.state = AtomicPolymerBackboneIteratorState.nextPolymer;
-                }
-            }
-        } else if (this.state === AtomicPolymerBackboneIteratorState.cycle) {
-            const { cyclicPolymerMap } = this.unit.model.atomicRanges;
-            this.value.centerA.element = this.value.centerB.element;
-            this.value.centerB.element = this.traceElementIndex[cyclicPolymerMap.get(this.residueSegment.index)!];
-            // TODO need to advance to a polymer that has two or more residues (can't assume it has)
-            this.state = AtomicPolymerBackboneIteratorState.nextPolymer;
-        }
-
-        this.hasNext = this.residueIt.hasNext || this.polymerIt.hasNext || this.state === AtomicPolymerBackboneIteratorState.cycle;
-        return this.value;
-    }
-
-    constructor(structure: Structure, private unit: Unit.Atomic) {
-        this.traceElementIndex = unit.model.atomicHierarchy.derived.residue.traceElementIndex as ArrayLike<ElementIndex>; // can assume it won't be -1 for polymer residues
-        this.polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
-        this.residueIt = Segmentation.transientSegments(unit.model.atomicHierarchy.residueAtomSegments, unit.elements);
-        this.value = createPolymerBackbonePair(structure, unit);
-        this.hasNext = this.residueIt.hasNext && this.polymerIt.hasNext;
-    }
-}
-
-const enum CoarsePolymerBackboneIteratorState { nextPolymer, nextElement }
-
-export class CoarsePolymerBackboneIterator implements Iterator<PolymerBackbonePair> {
-    private value: PolymerBackbonePair
-    private polymerIt: SortedRanges.Iterator<ElementIndex, ResidueIndex>
-    private polymerSegment: Segmentation.Segment<ResidueIndex>
-    private state: CoarsePolymerBackboneIteratorState = CoarsePolymerBackboneIteratorState.nextPolymer
-    private elementIndex: number
-    hasNext: boolean = false;
-
-    move() {
-        if (this.state === CoarsePolymerBackboneIteratorState.nextPolymer) {
-            if (this.polymerIt.hasNext) {
-                this.polymerSegment = this.polymerIt.move();
-                this.elementIndex = this.polymerSegment.start;
-                if (this.elementIndex + 1 < this.polymerSegment.end) {
-                    this.value.centerB.element = this.unit.elements[this.elementIndex];
-                    this.state = CoarsePolymerBackboneIteratorState.nextElement;
-                } else {
-                    this.state = CoarsePolymerBackboneIteratorState.nextPolymer;
-                }
-            }
-        }
-
-        if (this.state === CoarsePolymerBackboneIteratorState.nextElement) {
-            this.elementIndex += 1;
-            this.value.centerA.element = this.value.centerB.element;
-            this.value.centerB.element = this.unit.elements[this.elementIndex];
-            if (this.elementIndex + 1 >= this.polymerSegment.end) {
-                this.state = CoarsePolymerBackboneIteratorState.nextPolymer;
-            }
-        }
-
-        this.hasNext = this.elementIndex + 1 < this.polymerSegment.end || this.polymerIt.hasNext;
-        return this.value;
-    }
-
-    constructor(structure: Structure, private unit: Unit.Spheres | Unit.Gaussians) {
-        this.polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
-        this.value = createPolymerBackbonePair(structure, unit);
-        this.hasNext = this.polymerIt.hasNext;
-    }
-}

src/mol-repr/structure/visual/util/polymer/backbone.ts

@@ -0,0 +1,126 @@
+/**
+ * Copyright (c) 2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+import { Segmentation } from '../../../../../mol-data/int';
+import { SortedRanges } from '../../../../../mol-data/int/sorted-ranges';
+import { ElementIndex, ResidueIndex, Unit } from '../../../../../mol-model/structure';
+import { MoleculeType } from '../../../../../mol-model/structure/model/types';
+import { getPolymerRanges } from '../polymer';
+
+export type PolymerBackboneLinkCallback = (indexA: ElementIndex, indexB: ElementIndex, groupA: number, groupB: number, moleculeType: MoleculeType) => void
+
+export function eachPolymerBackboneLink(unit: Unit, callback: PolymerBackboneLinkCallback) {
+    switch (unit.kind) {
+        case Unit.Kind.Atomic: return eachAtomicPolymerBackboneLink(unit, callback);
+        case Unit.Kind.Spheres:
+        case Unit.Kind.Gaussians:
+            return eachCoarsePolymerBackboneLink(unit, callback);
+    }
+}
+
+function eachAtomicPolymerBackboneLink(unit: Unit.Atomic, callback: PolymerBackboneLinkCallback) {
+    const cyclicPolymerMap = unit.model.atomicRanges.cyclicPolymerMap;
+    const polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
+    const residueIt = Segmentation.transientSegments(unit.model.atomicHierarchy.residueAtomSegments, unit.elements);
+    const traceElementIndex = unit.model.atomicHierarchy.derived.residue.traceElementIndex as ArrayLike<ElementIndex>; // can assume it won't be -1 for polymer residues
+    const { moleculeType } = unit.model.atomicHierarchy.derived.residue;
+
+    let indexA = -1 as ResidueIndex;
+    let indexB = -1 as ResidueIndex;
+    let isFirst = true;
+    let firstGroup = -1;
+    let i = 0;
+    while (polymerIt.hasNext) {
+        isFirst = true;
+        firstGroup = i;
+        residueIt.setSegment(polymerIt.move());
+        while (residueIt.hasNext) {
+            if (isFirst) {
+                const index_1 = residueIt.move().index;
+                ++i;
+                if (!residueIt.hasNext)
+                    continue;
+                isFirst = false;
+                indexB = index_1;
+            }
+            const index = residueIt.move().index;
+            indexA = indexB;
+            indexB = index;
+            callback(traceElementIndex[indexA], traceElementIndex[indexB], i - 1, i, moleculeType[indexA]);
+            ++i;
+        }
+        if (cyclicPolymerMap.has(indexB)) {
+            indexA = indexB;
+            indexB = cyclicPolymerMap.get(indexA)!;
+            callback(traceElementIndex[indexA], traceElementIndex[indexB], i - 1, firstGroup, moleculeType[indexA]);
+        }
+    }
+}
+
+function eachCoarsePolymerBackboneLink(unit: Unit.Spheres | Unit.Gaussians, callback: PolymerBackboneLinkCallback) {
+    const polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
+    const { elements } = unit;
+
+    let isFirst = true;
+    let i = 0;
+    while (polymerIt.hasNext) {
+        isFirst = true;
+        const _a = polymerIt.move(), start = _a.start, end = _a.end;
+        for (let j = start, jl = end; j < jl; ++j) {
+            if (isFirst) {
+                ++j;
+                ++i;
+                if (j > jl)
+                    continue;
+                isFirst = false;
+            }
+            callback(elements[j - 1], elements[j], i - 1, i, 0 /* Unknown */);
+            ++i;
+        }
+    }
+}
+
+//
+
+export type PolymerBackboneElementCallback = (index: ElementIndex, group: number) => void
+
+export function eachPolymerBackboneElement(unit: Unit, callback: PolymerBackboneElementCallback) {
+    switch (unit.kind) {
+        case Unit.Kind.Atomic: return eachAtomicPolymerBackboneElement(unit, callback);
+        case Unit.Kind.Spheres:
+        case Unit.Kind.Gaussians:
+            return eachCoarsePolymerBackboneElement(unit, callback);
+    }
+}
+
+export function eachAtomicPolymerBackboneElement(unit: Unit.Atomic, callback: PolymerBackboneElementCallback) {
+    const polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
+    const residueIt = Segmentation.transientSegments(unit.model.atomicHierarchy.residueAtomSegments, unit.elements);
+    const traceElementIndex = unit.model.atomicHierarchy.derived.residue.traceElementIndex as ArrayLike<ElementIndex>; // can assume it won't be -1 for polymer residues
+
+    let i = 0;
+    while (polymerIt.hasNext) {
+        residueIt.setSegment(polymerIt.move());
+        while (residueIt.hasNext) {
+            const index = residueIt.move().index;
+            callback(traceElementIndex[index], i);
+            ++i;
+        }
+    }
+}
+
+function eachCoarsePolymerBackboneElement(unit: Unit.Spheres | Unit.Gaussians, callback: PolymerBackboneElementCallback) {
+    const polymerIt = SortedRanges.transientSegments(getPolymerRanges(unit), unit.elements);
+    const { elements } = unit;
+
+    let i = 0;
+    while (polymerIt.hasNext) {
+        const _a = polymerIt.move(), start = _a.start, end = _a.end;
+        for (let j = start, jl = end; j < jl; ++j) {
+            callback(elements[j], i);
+            ++i;
+        }
+    }
+}

src/mol-repr/structure/visual/util/polymer/curve-segment.ts

@@ -1,12 +1,12 @@
 /**
- * Copyright (c) 2018-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
 
 import { Vec3 } from '../../../../../mol-math/linear-algebra';
 import { NumberArray } from '../../../../../mol-util/type-helpers';
-import { lerp } from '../../../../../mol-math/interpolate';
+import { lerp, smoothstep } from '../../../../../mol-math/interpolate';
 
 // avoiding namespace lookup improved performance in Chrome (Aug 2020)
 const v3fromArray = Vec3.fromArray;
@@ -19,6 +19,8 @@ const v3copy = Vec3.copy;
 const v3cross = Vec3.cross;
 const v3orthogonalize = Vec3.orthogonalize;
 const v3matchDirection = Vec3.matchDirection;
+const v3scale = Vec3.scale;
+const v3add = Vec3.add;
 
 export interface CurveSegmentState {
     curvePoints: NumberArray,
@@ -92,6 +94,7 @@ const tangentVec = Vec3();
 const normalVec = Vec3();
 const binormalVec = Vec3();
 const prevNormal = Vec3();
+const nextNormal = Vec3();
 const firstTangentVec = Vec3();
 const lastTangentVec = Vec3();
 const firstNormalVec = Vec3();
@@ -116,8 +119,10 @@ export function interpolateNormals(state: CurveSegmentState, controls: CurveSegm
 
     v3copy(prevNormal, firstNormalVec);
 
+    const n1 = n - 1;
     for (let i = 0; i < n; ++i) {
-        const t = i === 0 ? 0 : 1 / (n - i);
+        const j = smoothstep(0, n1, i) * n1;
+        const t = i === 0 ? 0 : 1 / (n - j);
 
         v3fromArray(tangentVec, tangentVectors, i * 3);
 
@@ -129,6 +134,19 @@ export function interpolateNormals(state: CurveSegmentState, controls: CurveSegm
         v3normalize(binormalVec, v3cross(binormalVec, tangentVec, normalVec));
         v3toArray(binormalVec, binormalVectors, i * 3);
     }
+
+    for (let i = 1; i < n1; ++i) {
+        v3fromArray(prevNormal, normalVectors, (i - 1) * 3);
+        v3fromArray(normalVec, normalVectors, i * 3);
+        v3fromArray(nextNormal, normalVectors, (i + 1) * 3);
+
+        v3scale(normalVec, v3add(normalVec, prevNormal, v3add(normalVec, nextNormal, normalVec)), 1 / 3);
+        v3toArray(normalVec, normalVectors, i * 3);
+
+        v3fromArray(tangentVec, tangentVectors, i * 3);
+        v3normalize(binormalVec, v3cross(binormalVec, tangentVec, normalVec));
+        v3toArray(binormalVec, binormalVectors, i * 3);
+    }
 }
 
 export function interpolateSizes(state: CurveSegmentState, w0: number, w1: number, w2: number, h0: number, h1: number, h2: number, shift: number) {

src/mol-util/array.ts

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2018-2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
@@ -105,6 +105,29 @@ export function arraySetRemove<T>(xs: T[], x: T) {
     return true;
 }
 
+/**
+ * Caution, O(n^2) complexity. Only use for small input sizes.
+ * For larger inputs consider using `SortedArray`.
+ */
+export function arrayAreIntersecting<T>(xs: T[], ys: T[]) {
+    for (let i = 0, il = xs.length; i < il; ++i) {
+        if (ys.includes(xs[i])) return true;
+    }
+    return false;
+}
+
+/**
+ * Caution, O(n^2) complexity. Only use for small input sizes.
+ * For larger inputs consider using `SortedArray`.
+ */
+export function arrayIntersectionSize<T>(xs: T[], ys: T[]) {
+    let count = 0;
+    for (let i = 0, il = xs.length; i < il; ++i) {
+        if (ys.includes(xs[i])) count += 1;
+    }
+    return count;
+}
+
 export function arrayEqual<T>(xs?: ArrayLike<T>, ys?: ArrayLike<T>) {
     if (!xs || xs.length === 0) return !ys || ys.length === 0;
     if (!ys) return false;