Fix cel-shaded ambient color being stripped to luminance

CHANGELOG.md

@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file, following t
 Note that since we don't clearly distinguish between a public and private interfaces there will be changes in non-major versions that are potentially breaking. If we make breaking changes to less used interfaces we will highlight it in here.
 
 ## [Unreleased]
+- Fix cel-shaded ambient color being stripped to luminance (now uses full RGB, matching the classic lighting path)
 - 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

src/mol-gl/shader/chunks/apply-light-color.glsl.ts

@@ -78,7 +78,7 @@ export const apply_light_color = `
         }
         #pragma unroll_loop_end
 
-        outgoingLight += physicalMaterial.diffuseColor * luminance(uAmbientColor);
+        outgoingLight += physicalMaterial.diffuseColor * uAmbientColor;
     #else
         ReflectedLight reflectedLight = ReflectedLight(vec3(0.0), vec3(0.0), vec3(0.0), vec3(0.0));