Encode frame number in pixel data for pose sync

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

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1118 matching lines @@
 
   m_defaultVertexArrayObject = WebGLVertexArrayObject::create(
       this, WebGLVertexArrayObjectBase::VaoTypeDefault);
   addContextObject(m_defaultVertexArrayObject.get());
 
   m_boundVertexArrayObject = m_defaultVertexArrayObject;
 
   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(
           &WebGLRenderingContextBase::forceLostContext,
           wrapWeakPersistent(this), WebGLRenderingContextBase::RealLostContext,
           WebGLRenderingContextBase::Auto)));
   drawingBuffer()->contextProvider()->setErrorMessageCallback(
       convertToBaseCallback(
           WTF::bind(&WebGLRenderingContextBase::onErrorMessage,
                     wrapWeakPersistent(this))));
@@ skipping 213 matching lines @@
       !drawingBuffer()->defaultBufferRequiresAlphaChannelToBePreserved());
   drawingBuffer()->clearFramebuffers(clearMask);
 
   restoreStateAfterClear();
   drawingBuffer()->restoreFramebufferBindings();
   drawingBuffer()->setBufferClearNeeded(false);
 
   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() {
   if (!isContextLost())
     drawingBuffer()->setBufferClearNeeded(true);
 }
 
 void WebGLRenderingContextBase::setIsHidden(bool hidden) {
   m_isHidden = hidden;
   if (drawingBuffer())
@@ skipping 2751 matching lines @@
     return;
   contextGL()->SampleCoverage(value, invert);
 }
 
 void WebGLRenderingContextBase::scissor(GLint x,
                                         GLint y,
                                         GLsizei width,
                                         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);
 }
 
 void WebGLRenderingContextBase::shaderSource(WebGLShader* shader,
                                              const String& string) {
   if (isContextLost() || !validateWebGLObject("shaderSource", shader))
     return;
   String stringWithoutComments = StripComments(string).result();
   // TODO(danakj): Make validateShaderSource reject characters > 255 (or utf16 Strings)
   // so we don't need to use StringUTF8Adaptor.
@@ skipping 3259 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(
     HTMLCanvasElementOrOffscreenCanvas& result) const {
   if (canvas())
     result.setHTMLCanvasElement(canvas());
   else
     result.setOffscreenCanvas(getOffscreenCanvas());
 }
 
 }  // namespace blink