Make imageHeight optional (#517)

kainino0x · web-flow · commit 6867df944c66 · 2020-03-09T15:25:06.000-07:00
It's awkward to have to specify an `imageHeight` when you're not doing an array/3d texture copy (i.e. almost always).

Make it default to zero. Zero is valid iff `copySize.depth &gt; 1`
diff --git a/spec/index.bs b/spec/index.bs
@@ -2258,10 +2258,21 @@ dictionary GPUBufferCopyView {
     required GPUBuffer buffer;
     GPUSize64 offset = 0;
     required GPUSize32 rowPitch;
-    required GPUSize32 imageHeight;
+    GPUSize32 imageHeight = 0;
 };
 </script>
 
+<dl dfn-type=dict-member dfn-for=GPUBufferCopyView>
+    : <dfn>imageHeight</dfn>
+    ::
+        The pitch (measured as a multiple of {{GPUBufferCopyView/rowPitch}} bytes)
+        between different `z` values of the target texture.
+        For {{GPUTextureDimension/3d}} textures, `z` refers to the texture's depth.
+        For {{GPUTextureDimension/2d}} textures, `z` refers to the texture's array layers.
+
+        An `imageHeight` of zero is only valid for copies with a `copySize.depth` of 1.
+</dl>
+
 <script type=idl>
 dictionary GPUTextureCopyView {
     required GPUTexture texture;
