Fix state management of transform feedback buffers.

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
index a3da846049bfe5db49feaba7ced2aecc5124e88d..40e0dab53083c62e83a904103b3dd734f3c82529 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
@@ -154,7 +154,6 @@ WebGL2RenderingContextBase::WebGL2RenderingContextBase(
       m_boundCopyWriteBuffer(this, nullptr),
       m_boundPixelPackBuffer(this, nullptr),
       m_boundPixelUnpackBuffer(this, nullptr),
-      m_boundTransformFeedbackBuffer(this, nullptr),
       m_boundUniformBuffer(this, nullptr),
       m_currentBooleanOcclusionQuery(this, nullptr),
       m_currentTransformFeedbackPrimitivesWrittenQuery(this, nullptr),
@@ -179,7 +178,6 @@ WebGL2RenderingContextBase::WebGL2RenderingContextBase(
       m_boundCopyWriteBuffer(this, nullptr),
       m_boundPixelPackBuffer(this, nullptr),
       m_boundPixelUnpackBuffer(this, nullptr),
-      m_boundTransformFeedbackBuffer(this, nullptr),
       m_boundUniformBuffer(this, nullptr),
       m_currentBooleanOcclusionQuery(this, nullptr),
       m_currentTransformFeedbackPrimitivesWrittenQuery(this, nullptr),
@@ -209,7 +207,6 @@ void WebGL2RenderingContextBase::initializeNewContext() {
   m_boundCopyWriteBuffer = nullptr;
   m_boundPixelPackBuffer = nullptr;
   m_boundPixelUnpackBuffer = nullptr;
-  m_boundTransformFeedbackBuffer = nullptr;
   m_boundUniformBuffer = nullptr;
 
   m_currentBooleanOcclusionQuery = nullptr;
@@ -223,11 +220,15 @@ void WebGL2RenderingContextBase::initializeNewContext() {
   m_samplerUnits.resize(numCombinedTextureImageUnits);
 
   m_maxTransformFeedbackSeparateAttribs = 0;
+  // This must be queried before instantiating any transform feedback
+  // objects.
   contextGL()->GetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS,
                            &m_maxTransformFeedbackSeparateAttribs);
-  m_boundIndexedTransformFeedbackBuffers.clear();
-  m_boundIndexedTransformFeedbackBuffers.resize(
-      m_maxTransformFeedbackSeparateAttribs);
+  // Create a default transform feedback object so there is a place to
+  // hold any bound buffers.
+  m_defaultTransformFeedback = WebGLTransformFeedback::create(
+      this, WebGLTransformFeedback::TFTypeDefault);
+  m_transformFeedbackBinding = m_defaultTransformFeedback;
 
   GLint maxUniformBufferBindings = 0;
   contextGL()->GetIntegerv(GL_MAX_UNIFORM_BUFFER_BINDINGS,
@@ -4060,13 +4061,14 @@ ScriptValue WebGL2RenderingContextBase::getSyncParameter(
 WebGLTransformFeedback* WebGL2RenderingContextBase::createTransformFeedback() {
   if (isContextLost())
     return nullptr;
-  return WebGLTransformFeedback::create(this);
+  return WebGLTransformFeedback::create(this,
+                                        WebGLTransformFeedback::TFTypeUser);
 }
 
 void WebGL2RenderingContextBase::deleteTransformFeedback(
     WebGLTransformFeedback* feedback) {
   if (feedback == m_transformFeedbackBinding)
-    m_transformFeedbackBinding = nullptr;
+    m_transformFeedbackBinding = m_defaultTransformFeedback;
 
   deleteObject(feedback);
 }
@@ -4100,12 +4102,16 @@ void WebGL2RenderingContextBase::bindTransformFeedback(
     return;
   }
 
-  m_transformFeedbackBinding = feedback;
-
-  contextGL()->BindTransformFeedback(target, objectOrZero(feedback));
+  WebGLTransformFeedback* feedbackToBeBound;
   if (feedback) {
-    feedback->setTarget(target);
+    feedbackToBeBound = feedback;
+    feedbackToBeBound->setTarget(target);
+  } else {
+    feedbackToBeBound = m_defaultTransformFeedback.get();
   }
+
+  m_transformFeedbackBinding = feedbackToBeBound;
+  contextGL()->BindTransformFeedback(target, objectOrZero(feedbackToBeBound));
 }
 
 void WebGL2RenderingContextBase::beginTransformFeedback(GLenum primitiveMode) {
@@ -4307,14 +4313,16 @@ ScriptValue WebGL2RenderingContextBase::getIndexedParameter(
     return ScriptValue::createNull(scriptState);
 
   switch (target) {
-    case GL_TRANSFORM_FEEDBACK_BUFFER_BINDING:
-      if (index >= m_boundIndexedTransformFeedbackBuffers.size()) {
+    case GL_TRANSFORM_FEEDBACK_BUFFER_BINDING: {
+      WebGLBuffer* buffer = nullptr;
+      if (!m_transformFeedbackBinding->getBoundIndexedTransformFeedbackBuffer(
+              index, &buffer)) {
         synthesizeGLError(GL_INVALID_VALUE, "getIndexedParameter",
                           "index out of range");
         return ScriptValue::createNull(scriptState);
       }
-      return WebGLAny(scriptState,
-                      m_boundIndexedTransformFeedbackBuffers[index].get());
+      return WebGLAny(scriptState, buffer);
+    }
     case GL_UNIFORM_BUFFER_BINDING:
       if (index >= m_boundIndexedUniformBuffers.size()) {
         synthesizeGLError(GL_INVALID_VALUE, "getIndexedParameter",
@@ -4793,9 +4801,14 @@ ScriptValue WebGL2RenderingContextBase::getParameter(ScriptState* scriptState,
     case GL_TRANSFORM_FEEDBACK_ACTIVE:
       return getBooleanParameter(scriptState, pname);
     case GL_TRANSFORM_FEEDBACK_BUFFER_BINDING:
-      return WebGLAny(scriptState, m_boundTransformFeedbackBuffer.get());
+      return WebGLAny(
+          scriptState,
+          m_transformFeedbackBinding->getBoundTransformFeedbackBuffer());
     case GL_TRANSFORM_FEEDBACK_BINDING:
-      return WebGLAny(scriptState, m_transformFeedbackBinding.get());
+      if (!m_transformFeedbackBinding->isDefaultObject()) {
+        return WebGLAny(scriptState, m_transformFeedbackBinding.get());
+      }
+      return ScriptValue::createNull(scriptState);
     case GL_TRANSFORM_FEEDBACK_PAUSED:
       return getBooleanParameter(scriptState, pname);
     case GL_UNIFORM_BUFFER_BINDING:
@@ -4856,16 +4869,7 @@ bool WebGL2RenderingContextBase::validateCapability(const char* functionName,
 bool WebGL2RenderingContextBase::isBufferBoundToTransformFeedback(
     WebGLBuffer* buffer) {
   ASSERT(buffer);
-
-  if (m_boundTransformFeedbackBuffer == buffer)
-    return true;
-
-  for (size_t i = 0; i < m_boundIndexedTransformFeedbackBuffers.size(); ++i) {
-    if (m_boundIndexedTransformFeedbackBuffers[i] == buffer)
-      return true;
-  }
-
-  return false;
+  return m_transformFeedbackBinding->isBufferBoundToTransformFeedback(buffer);
 }
 
 bool WebGL2RenderingContextBase::isBufferBoundToNonTransformFeedback(
@@ -4995,7 +4999,7 @@ bool WebGL2RenderingContextBase::validateAndUpdateBufferBindTarget(
       m_boundPixelUnpackBuffer = buffer;
       break;
     case GL_TRANSFORM_FEEDBACK_BUFFER:
-      m_boundTransformFeedbackBuffer = buffer;
+      m_transformFeedbackBinding->setBoundTransformFeedbackBuffer(buffer);
       break;
     case GL_UNIFORM_BUFFER:
       m_boundUniformBuffer = buffer;
@@ -5037,13 +5041,11 @@ bool WebGL2RenderingContextBase::validateAndUpdateBufferBindBaseTarget(
 
   switch (target) {
     case GL_TRANSFORM_FEEDBACK_BUFFER:
-      if (index >= m_boundIndexedTransformFeedbackBuffers.size()) {
+      if (!m_transformFeedbackBinding->setBoundIndexedTransformFeedbackBuffer(
+              index, buffer)) {
         synthesizeGLError(GL_INVALID_VALUE, functionName, "index out of range");
         return false;
       }
-      m_boundIndexedTransformFeedbackBuffers[index] =
-          TraceWrapperMember<WebGLBuffer>(this, buffer);
-      m_boundTransformFeedbackBuffer = buffer;
       break;
     case GL_UNIFORM_BUFFER:
       if (index >= m_boundIndexedUniformBuffers.size()) {
@@ -5393,13 +5395,12 @@ ScriptValue WebGL2RenderingContextBase::getFramebufferAttachmentParameter(
 DEFINE_TRACE(WebGL2RenderingContextBase) {
   visitor->trace(m_readFramebufferBinding);
   visitor->trace(m_transformFeedbackBinding);
+  visitor->trace(m_defaultTransformFeedback);
   visitor->trace(m_boundCopyReadBuffer);
   visitor->trace(m_boundCopyWriteBuffer);
   visitor->trace(m_boundPixelPackBuffer);
   visitor->trace(m_boundPixelUnpackBuffer);
-  visitor->trace(m_boundTransformFeedbackBuffer);
   visitor->trace(m_boundUniformBuffer);
-  visitor->trace(m_boundIndexedTransformFeedbackBuffers);
   visitor->trace(m_boundIndexedUniformBuffers);
   visitor->trace(m_currentBooleanOcclusionQuery);
   visitor->trace(m_currentTransformFeedbackPrimitivesWrittenQuery);
@@ -5410,17 +5411,13 @@ DEFINE_TRACE(WebGL2RenderingContextBase) {
 }
 
 DEFINE_TRACE_WRAPPERS(WebGL2RenderingContextBase) {
-  visitor->traceWrappers(m_transformFeedbackBinding);
   visitor->traceWrappers(m_readFramebufferBinding);
+  visitor->traceWrappers(m_transformFeedbackBinding);
   visitor->traceWrappers(m_boundCopyReadBuffer);
   visitor->traceWrappers(m_boundCopyWriteBuffer);
   visitor->traceWrappers(m_boundPixelPackBuffer);
   visitor->traceWrappers(m_boundPixelUnpackBuffer);
-  visitor->traceWrappers(m_boundTransformFeedbackBuffer);
   visitor->traceWrappers(m_boundUniformBuffer);
-  for (auto& buf : m_boundIndexedTransformFeedbackBuffers) {
-    visitor->traceWrappers(buf);
-  }
   for (auto& buf : m_boundIndexedUniformBuffers) {
     visitor->traceWrappers(buf);
   }
@@ -5528,7 +5525,7 @@ WebGLBuffer* WebGL2RenderingContextBase::validateBufferDataTarget(
       buffer = m_boundPixelUnpackBuffer.get();
       break;
     case GL_TRANSFORM_FEEDBACK_BUFFER:
-      buffer = m_boundTransformFeedbackBuffer.get();
+      buffer = m_transformFeedbackBinding->getBoundTransformFeedbackBuffer();
       break;
     case GL_UNIFORM_BUFFER:
       buffer = m_boundUniformBuffer.get();
@@ -5627,8 +5624,6 @@ void WebGL2RenderingContextBase::removeBoundBuffer(WebGLBuffer* buffer) {
     m_boundPixelPackBuffer = nullptr;
   if (m_boundPixelUnpackBuffer == buffer)
     m_boundPixelUnpackBuffer = nullptr;
-  if (m_boundTransformFeedbackBuffer == buffer)
-    m_boundTransformFeedbackBuffer = nullptr;
   if (m_boundUniformBuffer == buffer)
     m_boundUniformBuffer = nullptr;
 
@@ -5640,6 +5635,11 @@ void WebGL2RenderingContextBase::restoreCurrentFramebuffer() {
   bindFramebuffer(GL_READ_FRAMEBUFFER, m_readFramebufferBinding.get());
 }
 
+GLint WebGL2RenderingContextBase::getMaxTransformFeedbackSeparateAttribs()
+    const {
+  return m_maxTransformFeedbackSeparateAttribs;
+}
+
 WebGLImageConversion::PixelStoreParams
 WebGL2RenderingContextBase::getPackPixelStoreParams() {
   WebGLImageConversion::PixelStoreParams params;