Merge pull request #1822 from corredD/codex/dot-morton-spheres

CHANGELOG.md

@@ -5,6 +5,7 @@ Note that since we don't clearly distinguish between a public and private interf
 
 ## [Unreleased]
 - Fix empty transforms default in `ShapeFromPly`
+- Use morton order for spheres in dot visual with lod-levels
 - Add `Camera.changed` event and rotation/translation setter/getter
 - Add `instanceGranularity: 'auto'` as a memory guard
 - Honor `instanceGranularity` in `Visual.getLoci`

src/mol-repr/volume/_spec/dot.spec.ts

@@ -0,0 +1,59 @@
+/**
+ * Copyright (c) 2026 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Ludovic Autin <autin@scripps.edu>
+ */
+
+import { CustomProperties } from '../../../mol-model/custom-property';
+import { Grid, Volume } from '../../../mol-model/volume';
+import { Mat4, Tensor } from '../../../mol-math/linear-algebra';
+import { createVolumeSphereImpostor } from '../dot';
+
+function createTestVolume(dimensions: [number, number, number], data: number[]): Volume {
+    return {
+        grid: {
+            transform: { kind: 'matrix', matrix: Mat4.identity() },
+            cells: Tensor.create(Tensor.Space(dimensions, [2, 1, 0]), Tensor.Data1(data)),
+            stats: { min: 0, max: 1, mean: 0.5, sigma: 0.5 },
+        } satisfies Grid,
+        instances: [{ transform: Mat4.identity() }],
+        sourceData: { kind: 'test', name: 'test', data: {} } as any,
+        customProperties: new CustomProperties(),
+        _propertyData: Object.create(null),
+        _localPropertyData: Object.create(null),
+    };
+}
+
+describe('volume dot representation', () => {
+    it('adds sphere impostor dots in Morton order for LOD sampling', () => {
+        const volume = createTestVolume([2, 2, 2], [
+            1, 1,
+            1, 1,
+            1, 1,
+            1, 1,
+        ]);
+        const spheres = createVolumeSphereImpostor(undefined as any, volume, 0, undefined as any, {
+            isoValue: Volume.IsoValue.absolute(0.5),
+            perturbPositions: false,
+            lodLevels: [{ minDistance: 0, maxDistance: 0, overlap: 0, stride: 0, scaleBias: 3 }],
+        } as any);
+
+        expect(Array.from(spheres.groupBuffer.ref.value)).toEqual([0, 4, 2, 6, 1, 5, 3, 7]);
+    });
+
+    it('adds sphere impostor dots in row-major order when no LOD levels are configured', () => {
+        const volume = createTestVolume([2, 2, 2], [
+            1, 1,
+            1, 1,
+            1, 1,
+            1, 1,
+        ]);
+        const spheres = createVolumeSphereImpostor(undefined as any, volume, 0, undefined as any, {
+            isoValue: Volume.IsoValue.absolute(0.5),
+            perturbPositions: false,
+            lodLevels: [],
+        } as any);
+
+        expect(Array.from(spheres.groupBuffer.ref.value)).toEqual([0, 1, 2, 3, 4, 5, 6, 7]);
+    });
+});

src/mol-repr/volume/dot.ts

@@ -67,7 +67,8 @@ export function VolumeSphereImpostorVisual(materialId: number): VolumeVisual<Vol
         setUpdateState: (state: VisualUpdateState, newVolume: Volume, currentVolume: Volume, newProps: PD.Values<VolumeSphereParams>, currentProps: PD.Values<VolumeSphereParams>, newTheme: Theme, currentTheme: Theme) => {
             state.createGeometry = (
                 !Volume.IsoValue.areSame(newProps.isoValue, currentProps.isoValue, newVolume.grid.stats) ||
-                newProps.perturbPositions !== currentProps.perturbPositions
+                newProps.perturbPositions !== currentProps.perturbPositions ||
+                newProps.lodLevels.length > 0 && currentProps.lodLevels.length === 0
             );
         },
         geometryUtils: Spheres.Utils,
@@ -128,32 +129,65 @@ export function createVolumeSphereImpostor(ctx: VisualContext, volume: Volume, k
 
     const p = Vec3();
     const [xn, yn, zn] = space.dimensions;
-
-    const count = Math.ceil((xn * yn * zn) / 10);
-    const builder = SpheresBuilder.create(count, Math.ceil(count / 2), spheres);
-
     const invert = isoVal < 0;
 
     // Precompute basis vectors and largest cell axis length
     const basis = props.perturbPositions ? getBasis(gridToCartn) : undefined;
 
-    for (let z = 0; z < zn; ++z) {
-        for (let y = 0; y < yn; ++y) {
-            for (let x = 0; x < xn; ++x) {
-                const value = space.get(data, x, y, z);
-                if (!invert && value < isoVal || invert && value > isoVal) continue;
+    const count = Math.ceil((xn * yn * zn) / 10);
+    const builder = SpheresBuilder.create(count, Math.ceil(count / 2), spheres);
 
-                const cellIdx = space.dataOffset(x, y, z);
-                if (basis) {
-                    Vec3.set(p, x, y, z);
-                    Vec3.transformMat4(p, p, gridToCartn);
-                    const offset = getRandomOffsetFromBasis(basis);
-                    Vec3.add(p, p, offset);
-                } else {
-                    Vec3.set(p, x, y, z);
-                    Vec3.transformMat4(p, p, gridToCartn);
+    const add = (x: number, y: number, z: number) => {
+        const value = space.get(data, x, y, z);
+        if (!invert && value < isoVal || invert && value > isoVal) return;
+
+        const cellIdx = space.dataOffset(x, y, z);
+        Vec3.set(p, x, y, z);
+        Vec3.transformMat4(p, p, gridToCartn);
+        if (basis) {
+            Vec3.add(p, p, getRandomOffsetFromBasis(basis));
+        }
+        builder.add(p[0], p[1], p[2], cellIdx);
+    };
+
+    // Morton ordering keeps stride-based LOD sampling spatially balanced.
+    // Only worthwhile when LOD levels are configured; otherwise use the
+    // direct row-major path to avoid the extra allocations and sort.
+    const useMortonOrder = props.lodLevels.length > 0;
+
+    if (useMortonOrder) {
+        // Recursive octree traversal over the bounding power-of-two cube,
+        // visiting children in Morton order (octant bit2=x, bit1=y, bit0=z).
+        // Octants whose origin already exceeds the grid extent are pruned,
+        // so out-of-range subtrees of non-cube grids cost ~O(log) per skip.
+        let size = 1;
+        while (size < xn || size < yn || size < zn) size <<= 1;
+
+        const visit = (x0: number, y0: number, z0: number, s: number): void => {
+            if (x0 >= xn || y0 >= yn || z0 >= zn) return;
+
+            if (s === 1) {
+                add(x0, y0, z0);
+                return;
+            }
+            const h = s >> 1;
+            visit(x0, y0, z0, h);
+            visit(x0, y0, z0 + h, h);
+            visit(x0, y0 + h, z0, h);
+            visit(x0, y0 + h, z0 + h, h);
+            visit(x0 + h, y0, z0, h);
+            visit(x0 + h, y0, z0 + h, h);
+            visit(x0 + h, y0 + h, z0, h);
+            visit(x0 + h, y0 + h, z0 + h, h);
+        };
+
+        visit(0, 0, 0, size);
+    } else {
+        for (let z = 0; z < zn; ++z) {
+            for (let y = 0; y < yn; ++y) {
+                for (let x = 0; x < xn; ++x) {
+                    add(x, y, z);
                 }
-                builder.add(p[0], p[1], p[2], cellIdx);
             }
         }
     }
@@ -320,6 +354,7 @@ const DotVisuals = {
 export const DotParams = {
     ...VolumeSphereParams,
     ...VolumePointParams,
+    sizeFactor: PD.Numeric(1, { min: 0, max: 10, step: 0.1 }),
     visuals: PD.MultiSelect(['sphere'], PD.objectToOptions(DotVisuals)),
     bumpFrequency: PD.Numeric(1, { min: 0, max: 10, step: 0.1 }, BaseGeometry.ShadingCategory),
 };
@@ -346,4 +381,4 @@ export const DotRepresentationProvider = VolumeRepresentationProvider({
     defaultSizeTheme: { name: 'uniform' },
     locationKinds: ['cell-location', 'position-location'],
     isApplicable: (volume: Volume) => !Volume.isEmpty(volume) && !Volume.Segmentation.get(volume)
-});
+});