update changelog and fix type

CHANGELOG.md

@@ -11,6 +11,7 @@ Note that since we don't clearly distinguish between a public and private interf
 - Fix coordinateSystem not handled in ``Structure.asParent``
 - Add dynamicBonds to ``Structure`` props (force re-calc on model change)
     - Expose as optional param in root structure transform helper
+- Add overpaint support to geometry exporters
 
 ## [v2.2.0] - 2021-07-31
 

src/extensions/geo-export/glb-exporter.ts

@@ -167,7 +167,7 @@ export class GlbExporter extends MeshExporter<GlbData> {
         const aTransform = values.aTransform.ref.value;
         const instanceCount = values.uInstanceCount.ref.value;
 
-        let interpolatedColors: Uint8Array;
+        let interpolatedColors: Uint8Array | undefined;
         if (colorType === 'volume' || colorType === 'volumeInstance') {
             const stride = isGeoTexture ? 4 : 3;
             interpolatedColors = GlbExporter.getInterpolatedColors(mesh!.vertices, mesh!.vertexCount, values, stride, colorType, webgl!);
@@ -201,7 +201,7 @@ export class GlbExporter extends MeshExporter<GlbData> {
 
                 // create a color buffer if needed
                 if (instanceIndex === 0 || !sameColorBuffer) {
-                    colorAccessorIndex = this.addColorBuffer(values, groups, vertexCount, instanceIndex, isGeoTexture, interpolatedColors!);
+                    colorAccessorIndex = this.addColorBuffer(values, groups, vertexCount, instanceIndex, isGeoTexture, interpolatedColors);
                 }
 
                 // glTF mesh