Encode frame number in pixel data for pose sync

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index 4c2ebadfd568aebe2fd11d95476bb8508c0a495a..a3781a2f04863db3093cf152391bfe0ff80e13e2 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -1136,7 +1136,11 @@ void WebGLRenderingContextBase::initializeNewContext() {
   m_vertexAttribType.resize(m_maxVertexAttribs);
 
   contextGL()->Viewport(0, 0, drawingBufferWidth(), drawingBufferHeight());
-  contextGL()->Scissor(0, 0, drawingBufferWidth(), drawingBufferHeight());
+  m_scissorBox[0] = m_scissorBox[1] = 0;
+  m_scissorBox[2] = drawingBufferWidth();
+  m_scissorBox[3] = drawingBufferHeight();
+  contextGL()->Scissor(m_scissorBox[0], m_scissorBox[1], m_scissorBox[2],
+                       m_scissorBox[3]);
 
   drawingBuffer()->contextProvider()->setLostContextCallback(
       convertToBaseCallback(WTF::bind(
@@ -1370,21 +1374,56 @@ WebGLRenderingContextBase::clearIfComposited(GLbitfield mask) {
   return combinedClear ? CombinedClear : JustClear;
 }
 
-void WebGLRenderingContextBase::restoreStateAfterClear() {
+void WebGLRenderingContextBase::restoreStateFromContext(int stateMask) {

[mthiesse, 2016/10/04 21:19:17]

Rather than a single restoreStateFromContext function which is hard (for me at
least) to validate in the general case, I would prefer individual functions for
each piece of state you're restoring (ex. restoreScissorBox(),
restoreScissorEnabled(), etc). Then you can explicitly restore each piece of
state you modify in your function that modifies them.

[klausw, 2016/10/04 23:08:14]

You convinced me, done.

   if (isContextLost())
     return;
 
-  // Restore the state that the context set.
-  if (m_scissorEnabled)
-    contextGL()->Enable(GL_SCISSOR_TEST);
-  contextGL()->ClearColor(m_clearColor[0], m_clearColor[1], m_clearColor[2],
-                          m_clearColor[3]);
-  contextGL()->ColorMask(m_colorMask[0], m_colorMask[1], m_colorMask[2],
-                         m_colorMask[3]);
-  contextGL()->ClearDepthf(m_clearDepth);
-  contextGL()->ClearStencil(m_clearStencil);
-  contextGL()->StencilMaskSeparate(GL_FRONT, m_stencilMask);
-  contextGL()->DepthMask(m_depthMask);
+  if (stateMask & StateScissorEnabled) {
+    if (m_scissorEnabled) {
+      contextGL()->Enable(GL_SCISSOR_TEST);
+    } else {
+      contextGL()->Disable(GL_SCISSOR_TEST);
+    }
+  }
+
+  if (stateMask & StateScissorBox) {
+    contextGL()->Scissor(m_scissorBox[0], m_scissorBox[1], m_scissorBox[2],
+                         m_scissorBox[3]);
+  }
+
+  if (stateMask & StateClearColor) {
+    contextGL()->ClearColor(m_clearColor[0], m_clearColor[1], m_clearColor[2],
+                            m_clearColor[3]);
+  }
+
+  if (stateMask & StateColorMask) {
+    contextGL()->ColorMask(m_colorMask[0], m_colorMask[1], m_colorMask[2],
+                           m_colorMask[3]);
+  }
+
+  if (stateMask & StateClearDepthf) {
+    contextGL()->ClearDepthf(m_clearDepth);
+  }
+
+  if (stateMask & StateClearStencil) {
+    contextGL()->ClearStencil(m_clearStencil);
+  }
+
+  if (stateMask & StateStencilMaskSeparate) {
+    contextGL()->StencilMaskSeparate(GL_FRONT, m_stencilMask);
+  }
+
+  if (stateMask & StateDepthMask) {
+    contextGL()->DepthMask(m_depthMask);
+  }
+}
+
+void WebGLRenderingContextBase::restoreStateAfterClear() {
+  // Restore clear-related state items back to what the context had set.
+  restoreStateFromContext(StateScissorEnabled | StateClearColor |
+                          StateColorMask | StateClearDepthf |
+                          StateClearStencil | StateStencilMaskSeparate |
+                          StateDepthMask);
 }
 
 void WebGLRenderingContextBase::markLayerComposited() {
@@ -4156,6 +4195,10 @@ void WebGLRenderingContextBase::scissor(GLint x,
                                         GLsizei height) {
   if (isContextLost())
     return;
+  m_scissorBox[0] = x;
+  m_scissorBox[1] = y;
+  m_scissorBox[2] = width;
+  m_scissorBox[3] = height;
   contextGL()->Scissor(x, y, width, height);
 }