Bug 1492723 - Use EGL_MOZ_context_create_provoking_vertex_dont_care. r=mattwoodrow

MozReview-Commit-ID: It8fOzqiFIe

--HG--
extra : rebase_source : 805c8e59427cd50e999b08dec44148a3349b24c6
extra : amend_source : c2a816122bb819d5e83a9156e645d42222099361

gfx/gl/GLContextProviderEGL.cpp

@@ -534,6 +534,8 @@ GLContextEGL::HoldSurface(gfxASurface* aSurf) {
     mThebesSurface = aSurf;
 }
 
+#define LOCAL_EGL_CONTEXT_PROVOKING_VERTEX_DONT_CARE_MOZ 0x6000
+
 already_AddRefed<GLContextEGL>
 GLContextEGL::CreateGLContext(CreateContextFlags flags,
                 const SurfaceCaps& caps,
@@ -567,6 +569,13 @@ GLContextEGL::CreateGLContext(CreateContextFlags flags,
         required_attribs.push_back(LOCAL_EGL_TRUE);
     }
 
+    if (flags & CreateContextFlags::PROVOKING_VERTEX_DONT_CARE &&
+        egl->IsExtensionSupported(GLLibraryEGL::MOZ_create_context_provoking_vertex_dont_care))
+    {
+        required_attribs.push_back(LOCAL_EGL_CONTEXT_PROVOKING_VERTEX_DONT_CARE_MOZ);
+        required_attribs.push_back(LOCAL_EGL_TRUE);
+    }
+
     std::vector<EGLint> robustness_attribs;
     std::vector<EGLint> rbab_attribs; // RBAB: Robust Buffer Access Behavior
     if (flags & CreateContextFlags::PREFER_ROBUSTNESS) {

gfx/gl/GLContextTypes.h

@@ -59,6 +59,8 @@ enum class CreateContextFlags : uint8_t {
     PREFER_ROBUSTNESS = 1 << 5,
 
     HIGH_POWER = 1 << 6,
+
+    PROVOKING_VERTEX_DONT_CARE = 1 << 7,
 };
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(CreateContextFlags)
 

gfx/gl/GLLibraryEGL.cpp

@@ -69,7 +69,8 @@ static const char* sEGLExtensionNames[] = {
     "EGL_ANGLE_device_creation",
     "EGL_ANGLE_device_creation_d3d11",
     "EGL_KHR_surfaceless_context",
-    "EGL_KHR_create_context_no_error"
+    "EGL_KHR_create_context_no_error",
+    "EGL_MOZ_create_context_provoking_vertex_dont_care"
 };
 
 #if defined(ANDROID)

gfx/gl/GLLibraryEGL.h

@@ -97,6 +97,7 @@ public:
         ANGLE_device_creation_d3d11,
         KHR_surfaceless_context,
         KHR_create_context_no_error,
+        MOZ_create_context_provoking_vertex_dont_care,
         Extensions_Max
     };
 

gfx/webrender_bindings/RenderThread.cpp

@@ -809,6 +809,12 @@ CreateGLContextANGLE()
   auto* egl = gl::GLLibraryEGL::Get();
   auto flags = gl::CreateContextFlags::PREFER_ES3;
 
+  if (egl->IsExtensionSupported(
+     gl::GLLibraryEGL::MOZ_create_context_provoking_vertex_dont_care))
+  {
+     flags |= gl::CreateContextFlags::PROVOKING_VERTEX_DONT_CARE;
+  }
+
   // Create GLContext with dummy EGLSurface, the EGLSurface is not used.
   // Instread we override it with EGLSurface of SwapChain's back buffer.
   RefPtr<gl::GLContext> gl = gl::GLContextProviderEGL::CreateHeadless(flags, &discardFailureId);