WebGL 2: add read/write framebuffer binding points to related APIs

Source/core/html/canvas/WebGL2RenderingContextBase.cpp

Index: Source/core/html/canvas/WebGL2RenderingContextBase.cpp
diff --git a/Source/core/html/canvas/WebGL2RenderingContextBase.cpp b/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
index b7f4c18bfc6acc0154ef08ed625f80ad26cbaa0a..498f5a7b5d67a671820ae0d6447865e77ccafb67 100644
--- a/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
@@ -1343,6 +1343,31 @@ void WebGL2RenderingContextBase::bindFramebuffer(GLenum target, WebGLFramebuffer
     setFramebuffer(target, buffer);
 }
 
+void WebGL2RenderingContextBase::deleteFramebuffer(WebGLFramebuffer* framebuffer)
+{
+    if (!deleteObject(framebuffer))
+        return;
+    GLenum target = 0;
+    if (framebuffer == m_framebufferBinding) {
+        if (framebuffer == m_readFramebufferBinding) {
+            target = GL_FRAMEBUFFER;
+            m_framebufferBinding = nullptr;
+            m_readFramebufferBinding = nullptr;
+        } else {
+            target = GL_DRAW_FRAMEBUFFER;
+            m_framebufferBinding = nullptr;
+        }
+    } else if (framebuffer == m_readFramebufferBinding) {
+        target = GL_READ_FRAMEBUFFER;
+        m_readFramebufferBinding = nullptr;
+    }
+    if (target) {
+        drawingBuffer()->setFramebufferBinding(0, target);
+        // Have to call bindFramebuffer here to bind back to internal fbo.

[bajones, 2015/05/06 17:47:53]

Comment doesn't match associated line. Should be // Have to call
drawingBuffer->bind()...?

[yunchao, 2015/05/22 09:54:35]

Acknowledged.

+        drawingBuffer()->bind(target);
+    }
+}
+
 ScriptValue WebGL2RenderingContextBase::getParameter(ScriptState* scriptState, GLenum pname)
 {
     if (isContextLost())
@@ -1712,4 +1737,29 @@ ScriptValue WebGL2RenderingContextBase::getTexParameter(ScriptState* scriptState
     }
 }
 
+void WebGL2RenderingContextBase::restoreCurrentFramebuffer()
+{
+    bindFramebuffer(GL_DRAW_FRAMEBUFFER, m_framebufferBinding.get());
+    bindFramebuffer(GL_READ_FRAMEBUFFER, m_readFramebufferBinding.get());
+}
+
+GLenum WebGL2RenderingContextBase::boundFramebufferColorFormat()
+{
+    GLenum colorFormat = 0, readColorFormat = 0, defaultColorFormat = GL_RGB;
+    if (m_requestedAttributes.alpha())
+        defaultColorFormat = GL_RGBA;
+    if (m_framebufferBinding && m_framebufferBinding->object())
+        colorFormat = m_framebufferBinding->colorBufferFormat();
+    if (m_readFramebufferBinding && m_readFramebufferBinding->object())
+        readColorFormat = m_readFramebufferBinding->colorBufferFormat();
+    // Both read and draw framebuffer are bound to FBO
+    if (colorFormat != 0 && readColorFormat != 0)
+        return colorFormat & readColorFormat;

[Ken Russell (switch to Gerrit), 2015/05/06 21:17:33]

I don't understand what this code is attempting to do -- it isn't legal to do a
bitwise "or" of constants like GL_RGB and GL_RGBA.

The only situation where boundFramebufferColorFormat is called is to check the
format of the read buffer (or read framebuffer) against the internal format of a
texture for CopyTexImage2D and CopyTexSubImage3D operations. This shouldn't be
looking at the draw framebuffer in WebGL 2.0 / ES 3.0.

[yunchao, 2015/05/22 09:54:35]

I thought that both the read buffer and the draw buffer should contain the
internal format of a texture for copyTexImage2D. So I do a bitwise 'and' when
both read FB and draw FB are existed. 

Code has been updated to handle read Framebuffer only.

+    // Either read or draw framebuffe is bound to FBO
+    if (colorFormat != 0 || readColorFormat != 0)
+        return colorFormat & defaultColorFormat;
+    // No framebuffer is bound to FBO
+    return defaultColorFormat;
+}
+
 } // namespace blink