commit 6d1e2137d23fbe2a411a62306cbad5241fd591ed
author Kai Ninomiya <kainino@chromium.org> Thu Sep 05 23:05:45 2024 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Sep 05 23:05:45 2024 +0000
tree 00b9d825a9ebc9765809256fffd4bb98d4231b21
parent a46bbf99f758dbb3cc4cbe67793cbb09e8ff7cf6

emdawnwebgpu: support Premultiplied canvas output

Port of this Emscripten fix into emdawnwebgpu:
https://github.com/emscripten-core/emscripten/pull/22494/files

Bug: https://github.com/emscripten-core/emscripten/issues/22491
Change-Id: Id3ed385d47ce2045d20e61f31e890a6f459ffb88
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/205075
Reviewed-by: Loko Kung <lokokung@google.com>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>

src/dawn/dawn.json

diff --git a/src/dawn/dawn.json b/src/dawn/dawn.json
index 60bdaab7..10a534f 100644
--- a/src/dawn/dawn.json
+++ b/src/dawn/dawn.json
@@ -1250,7 +1250,7 @@
     "composite alpha mode": {
         "category": "enum",
         "values": [
-            {"value": 0, "name": "auto"},
+            {"value": 0, "name": "auto", "jsrepr": "undefined"},
             {"value": 1, "name": "opaque"},
             {"value": 2, "name": "premultiplied"},
             {"value": 3, "name": "unpremultiplied"},

third_party/emdawnwebgpu/library_webgpu.js

diff --git a/third_party/emdawnwebgpu/library_webgpu.js b/third_party/emdawnwebgpu/library_webgpu.js
index 10d6aab..0c5e132 100644
--- a/third_party/emdawnwebgpu/library_webgpu.js
+++ b/third_party/emdawnwebgpu/library_webgpu.js
@@ -2364,10 +2364,6 @@
     var viewFormatCount = {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.viewFormatCount) }}};
     var viewFormats = {{{ makeGetValue('config', C_STRUCTS.WGPUSurfaceConfiguration.viewFormats, '*') }}};
     assert(viewFormatCount === 0 && viewFormats === 0, "TODO: Support viewFormats.");
-    var alphaMode = {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.alphaMode) }}};
-    assert(alphaMode === {{{ gpu.CompositeAlphaMode.Auto }}} ||
-      alphaMode === {{{ gpu.CompositeAlphaMode.Opaque }}},
-      "TODO: Support WGPUCompositeAlphaMode_Premultiplied.");
     assert({{{ gpu.PresentMode.Fifo }}} ===
       {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.presentMode) }}});
 #endif
@@ -2390,7 +2386,8 @@
       "format": WebGPU.TextureFormat[
         {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.format) }}}],
       "usage": {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.usage) }}},
-      "alphaMode": "opaque",
+      "alphaMode": WebGPU.CompositeAlphaMode[
+        {{{ gpu.makeGetU32('config', C_STRUCTS.WGPUSurfaceConfiguration.alphaMode) }}}],
     };
     context.configure(configuration);
   },