Bug 1616457 - Fix failures in conformance/extensions/webgl-draw-buffers. r=lsalzman

We must not check frag output type agreement if colorMask(0,0,0,0).
We must allow drawing with no frag outputs, leaving color values
unchanged. (evidently this is used enough that we spec'd it this way?)

Differential Revision: https://phabricator.services.mozilla.com/D63287

--HG--
extra : moz-landing-system : lando

dom/canvas/WebGLContext.h

@@ -1203,7 +1203,7 @@ class WebGLContext : public VRefCounted, public SupportsWeakPtr<WebGLContext> {
   GLuint mStencilValueMaskBack = 0;
   GLuint mStencilWriteMaskFront = 0;
   GLuint mStencilWriteMaskBack = 0;
-  uint8_t mColorWriteMask = 0;  // bitmask
+  uint8_t mColorWriteMask = 0xf;  // bitmask
   realGLboolean mDepthWriteMask = 0;
   GLfloat mColorClearValue[4];
   GLint mStencilClearValue = 0;

dom/canvas/WebGLContextDraw.cpp

@@ -443,18 +443,6 @@ const webgl::CachedDrawFetchLimits* ValidateDraw(WebGLContext* const webgl,
     if (fb) {
       const auto& info = *fb->GetCompletenessInfo();
       fbZLayerCount = info.zLayerCount;
-
-      for (const auto& attach : fb->ColorDrawBuffers()) {
-        const auto i =
-            uint8_t(attach->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0);
-        const auto& imageInfo = attach->GetImageInfo();
-        if (!imageInfo) continue;
-        const auto& dstBaseType = imageInfo->mFormat->format->baseType;
-        if (!fnValidateFragOutputType(i, dstBaseType)) return nullptr;
-      }
-    } else {
-      if (!fnValidateFragOutputType(0, webgl::TextureBaseType::Float))
-        return nullptr;
     }
 
     if (fbZLayerCount != linkInfo->zLayerCount) {
@@ -463,6 +451,22 @@ const webgl::CachedDrawFetchLimits* ValidateDraw(WebGLContext* const webgl,
           uint32_t{linkInfo->zLayerCount}, uint32_t{fbZLayerCount});
       return nullptr;
     }
+
+    if (webgl->mColorWriteMask) {
+      if (fb) {
+        for (const auto& attach : fb->ColorDrawBuffers()) {
+          const auto i =
+              uint8_t(attach->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0);
+          const auto& imageInfo = attach->GetImageInfo();
+          if (!imageInfo) continue;
+          const auto& dstBaseType = imageInfo->mFormat->format->baseType;
+          if (!fnValidateFragOutputType(i, dstBaseType)) return nullptr;
+        }
+      } else {
+        if (!fnValidateFragOutputType(0, webgl::TextureBaseType::Float))
+          return nullptr;
+      }
+    }
   }
 
   // -

dom/canvas/WebGLContextValidate.cpp

@@ -285,7 +285,6 @@ bool WebGLContext::InitAndValidateGL(FailureReason* const out_failReason) {
 
   // These are the default values, see 6.2 State tables in the
   // OpenGL ES 2.0.25 spec.
-  mColorWriteMask = 0x0f;
   mDriverColorMask = mColorWriteMask;
   mColorClearValue[0] = 0.f;
   mColorClearValue[1] = 0.f;

dom/canvas/WebGLProgram.cpp

@@ -386,6 +386,14 @@ RefPtr<const webgl::LinkedProgramInfo> QueryProgramInfo(WebGLProgram* prog,
         // shader, FragData[1] will be present. FragData[0] is valid for non-MRT
         // shaders.
         drawBuffers = webgl->GLMaxDrawBuffers();
+      } else if (translatedSource.find("(gl_FragColor") == std::string::npos &&
+                 translatedSource.find("(webgl_FragColor") ==
+                     std::string::npos &&
+                 translatedSource.find("(gl_FragData") == std::string::npos &&
+                 translatedSource.find("(webgl_FragData") ==
+                     std::string::npos) {
+        // We have to support no-color-output shaders?
+        drawBuffers = 0;
       }
 
       for (uint32_t i = 0; i < drawBuffers; ++i) {

dom/canvas/test/webgl-conf/generated-mochitest.ini

@@ -6921,8 +6921,8 @@ subsuite = webgl2-core
 fail-if = 1
 [generated/test_2_conformance2__textures__misc__tex-unpack-params.html]
 subsuite = webgl2-core
-fail-if = (os == 'mac')
 skip-if = (os == 'mac' && debug)
+fail-if = (os == 'mac')
 [generated/test_2_conformance2__textures__misc__texel-fetch-undefined.html]
 subsuite = webgl2-core
 [generated/test_2_conformance2__textures__misc__texture-npot.html]
@@ -9004,8 +9004,8 @@ subsuite = webgl2-core
 subsuite = webgl2-core
 [generated/test_2_conformance__textures__misc__texture-corner-case-videos.html]
 subsuite = webgl2-core
-fail-if = (os == 'linux' && os_version == '18.04')
 skip-if = (os == 'android')
+fail-if = (os == 'linux' && os_version == '18.04')
 [generated/test_2_conformance__textures__misc__texture-cube-as-fbo-attachment.html]
 subsuite = webgl2-core
 [generated/test_2_conformance__textures__misc__texture-draw-with-2d-and-cube.html]
@@ -10926,8 +10926,6 @@ subsuite = webgl1-core
 subsuite = webgl1-core
 [generated/test_conformance__extensions__webgl-draw-buffers.html]
 subsuite = webgl1-core
-fail-if = (os != 'android')
-skip-if = (os == 'linux')
 [generated/test_conformance__extensions__webgl-multi-draw.html]
 subsuite = webgl1-core
 [generated/test_conformance__glsl__bugs__angle-ambiguous-function-call.html]

dom/canvas/test/webgl-conf/mochitest-errata.ini

@@ -263,12 +263,6 @@ fail-if = 1 # https://github.com/KhronosGroup/WebGL/pull/2908
 # Asserts on linux debug. Crashes on Android.
 skip-if = (os == 'linux') || (os == 'android')
 
-[generated/test_conformance__extensions__webgl-draw-buffers.html]
-# Crashes
-skip-if = (os == 'linux')
-# New validation that shaders with no outputs cannot have non-null draw buffers attached.
-fail-if = (os != 'android')
-
 [generated/test_conformance__glsl__constructors__glsl-construct-bvec3.html]
 # Crashes from libglsl.so
 # application crashed [@ jemalloc_crash] on Android