calls transform function on constant attribute updates

modules/core/src/lib/attribute/attribute-manager.ts

@@ -208,7 +208,7 @@ export default class AttributeManager {
       } else if (
         typeof accessorName === 'string' &&
         !buffers[accessorName] &&
-        attribute.setConstantValue(props[accessorName])
+        attribute.setConstantValue(props[accessorName], context)
       ) {
         // Step 3: try set constant value from props
         // Note: if buffers[accessorName] is supplied, ignore props[accessorName]
@@ -380,7 +380,7 @@ export default class AttributeManager {
       // The attribute is flagged as constant outside of an update cycle
       // Skip allocation and updater call
       // @ts-ignore value can be set to an array by user but always cast to typed array during attribute update
-      attribute.setConstantValue(attribute.value);
+      attribute.setConstantValue(attribute.value, context);
       return;
     }
 

modules/core/src/lib/attribute/attribute.ts

@@ -254,7 +254,7 @@ export default class Attribute extends DataColumn<AttributeOptions, AttributeInt
 
   // Use generic value
   // Returns true if successful
-  setConstantValue(value?: NumericArray): boolean {
+  setConstantValue(value?: any, context?: any): boolean {
     // TODO(ibgreen): WebGPU does not support constant values,
     // they will be emulated as buffers instead for now.
     const isWebGPU = this.device.type === 'webgpu';
@@ -270,7 +270,8 @@ export default class Attribute extends DataColumn<AttributeOptions, AttributeInt
       return false;
     }
 
-    const hasChanged = this.setData({constant: true, value});
+    const objectValue = this.settings.transform ? this.settings.transform.call(context, value) : value;
+    const hasChanged = this.setData({constant:true, value: objectValue});
 
     if (hasChanged) {
       this.setNeedsRedraw();