[webgpu] Add Surface API

src/library_webgpu.js

@@ -99,13 +99,6 @@ wgpu${type}Release: (id) => WebGPU.mgr${type}.release(id),`;
       DeviceLost: 2,
       Unknown: 3,
     },
-    CompositeAlphaMode: [
-      'auto',
-      'opaque',
-      'premultiplied',
-      'unpremultiplied',
-      'inherit',
-    ],
     CreatePipelineAsyncStatus: {
       Success: 0,
       ValidationError: 1,
@@ -575,14 +568,6 @@ var LibraryWebGPU = {
       'store',
       'discard',
     ],
-    SurfaceGetCurrentTextureStatus: [
-      'success',
-      'timeout',
-      'outdated',
-      'lost',
-      'out-of-memory',
-      'device-lost',
-    ],
     TextureAspect: [
       undefined,
       'all',
@@ -2734,26 +2719,20 @@ var LibraryWebGPU = {
     context.configure(configuration);
   },
 
-  wgpuSurfaceGetCapabilities: (surfaceId, adapterId, capabilitiesPtr) => {
-    if (capabilitiesPtr !== 0) {
-      {{{ makeSetValue('capabilitiesPtr', C_STRUCTS.WGPUSurfaceCapabilities.formatCount, '1', 'i32') }}};
-      var format = navigator["gpu"]["getPreferredCanvasFormat"]();
-      var formatsPtr = WebGPU.Int_PreferredFormat[format]; // FIXME
-      {{{ makeSetValue('capabilitiesPtr', C_STRUCTS.WGPUSurfaceCapabilities.formats, 'formatsPtr', '*') }}};
-      // "presentModeCount",
-      // "presentModes",
-      // "alphaModeCount",
-      // "alphaModes"
-    }
-  },
-
   wgpuSurfaceGetCurrentTexture: (surfaceId, surfaceTexturePtr) => {
+    {{{ gpu.makeCheck('surfaceTexturePtr') }}}
     var context = WebGPU.mgrSurface.get(surfaceId);
-    var texture = WebGPU.mgrTexture.create(context.getCurrentTexture());
-    if (surfaceTexturePtr !== 0) {
+
+    try {
+      var texture = WebGPU.mgrTexture.create(context.getCurrentTexture());
       {{{ makeSetValue('surfaceTexturePtr', C_STRUCTS.WGPUSurfaceTexture.texture, 'texture', '*') }}};
       {{{ makeSetValue('surfaceTexturePtr', C_STRUCTS.WGPUSurfaceTexture.suboptimal, '0', 'i32') }}};
-      {{{ makeSetValue('surfaceTexturePtr', C_STRUCTS.WGPUSurfaceTexture.status, '0', 'i32') }}};
+      {{{ makeSetValue('surfaceTexturePtr', C_STRUCTS.WGPUSurfaceTexture.status, /*Success=*/0, 'i32') }}};
+    } catch (ex) {
+#if ASSERTIONS
+      err(`wgpuSurfaceGetCurrentTexture() failed: ${ex}`);
+#endif
+      {{{ makeSetValue('surfaceTexturePtr', C_STRUCTS.WGPUSurfaceTexture.status, /*Timeout=*/1, 'i32') }}};
     }
   },
 

system/lib/webgpu/webgpu.cpp

@@ -9,8 +9,19 @@
 
 #include <webgpu/webgpu.h>
 
+#include <array>
 #include <cassert>
 
+static constexpr std::array<WGPUTextureFormat, 3>
+    kBGRA8UnormPreferredContextFormats = {WGPUTextureFormat_BGRA8Unorm,
+                                          WGPUTextureFormat_RGBA8Unorm,
+                                          WGPUTextureFormat_RGBA16Float};
+
+static constexpr std::array<WGPUTextureFormat, 3>
+    kRGBA8UnormPreferredContextFormats = {WGPUTextureFormat_RGBA8Unorm,
+                                          WGPUTextureFormat_BGRA8Unorm,
+                                          WGPUTextureFormat_RGBA16Float};
+
 //
 // WebGPU function definitions, with methods organized by "class". Note these
 // don't need to be extern "C" because they are already declared in webgpu.h.
@@ -27,3 +38,24 @@ WGPUInstance wgpuCreateInstance(const WGPUInstanceDescriptor* descriptor) {
 
 void wgpuInstanceReference(WGPUInstance) { /* no-op for now */ }
 void wgpuInstanceRelease(WGPUInstance) { /* no-op for now */ }
+
+// WGPUSurface
+
+void wgpuSurfaceGetCapabilities(WGPUSurface surface,
+                                WGPUAdapter adapter,
+                                WGPUSurfaceCapabilities* capabilities) {
+  WGPUTextureFormat preferredFormat =
+      wgpuSurfaceGetPreferredFormat(surface, adapter);
+  assert(preferredFormat == WGPUTextureFormat_BGRA8Unorm ||
+         preferredFormat == WGPUTextureFormat_RGBA8Unorm);
+  capabilities->formatCount = 3;
+  if (preferredFormat == WGPUTextureFormat_RGBA8Unorm) {
+    capabilities->formats = reinterpret_cast<const WGPUTextureFormat*>(
+        kBGRA8UnormPreferredContextFormats.data());
+  } else {
+    capabilities->formats = reinterpret_cast<const WGPUTextureFormat*>(
+        kRGBA8UnormPreferredContextFormats.data());
+  }
+
+  // TODO: What do we return for presentModes and alphaModes?
+};

test/webgpu_basic_rendering.cpp

@@ -398,8 +398,7 @@ void run() {
 
         wgpu::SurfaceConfiguration config{
             .device = device,
-            .format = wgpu::TextureFormat::BGRA8Unorm,
-            // .format = capabilities.formats[0],
+            .format = capabilities.formats[0],
             .usage = wgpu::TextureUsage::RenderAttachment,
             .alphaMode = capabilities.alphaModes[0],
             .width = kWidth,