Allow zero sized system window FBO to be declared complete, and let the…

src/libGLESv2/Framebuffer.cpp

@@ -457,9 +457,8 @@ int Framebuffer::getSamples()
 
 GLenum DefaultFramebuffer::completeness()
 {
-    // The default framebuffer should always be complete
-    ASSERT(Framebuffer::completeness() == GL_FRAMEBUFFER_COMPLETE);
-
+    // The default framebuffer *must* always be complete, though it may not be
+    // subject to the same rules as application FBOs. ie, it could have 0x0 size.
     return GL_FRAMEBUFFER_COMPLETE;
 }
 

src/libGLESv2/renderer/RenderTarget.h

@@ -20,7 +20,15 @@ namespace rx
 class RenderTarget
 {
   public:
-    RenderTarget() {};
+    RenderTarget()
+    {
+        mWidth = 0;
+        mHeight = 0;
+        mInternalFormat = GL_NONE;
+        mActualFormat = GL_NONE;
+        mSamples = 0;
+    }
+
     virtual ~RenderTarget() {};
 
     GLsizei getWidth() { return mWidth; }

src/libGLESv2/renderer/RenderTarget11.cpp

@@ -141,6 +141,7 @@ RenderTarget11::RenderTarget11(Renderer *renderer, ID3D11RenderTargetView *rtv,
     mRenderTarget = rtv;
     mDepthStencil = NULL;
     mShaderResource = srv;
+    mSubresourceIndex = 0;
 
     if (mRenderTarget && mTexture)
     {
@@ -167,7 +168,7 @@ RenderTarget11::RenderTarget11(Renderer *renderer, ID3D11DepthStencilView *dsv,
     mRenderTarget = NULL;
     mDepthStencil = dsv;
     mShaderResource = srv;
-    mTexture = tex;
+    mSubresourceIndex = 0;
 
     if (mDepthStencil && mTexture)
     {

src/libGLESv2/renderer/Renderer11.cpp

@@ -750,6 +750,14 @@ bool Renderer11::applyRenderTarget(gl::Framebuffer *framebuffer)
             return false;
         }
 
+        // check for zero-sized default framebuffer, which is a special case.
+        // in this case we do not wish to modify any state and just silently return false.
+        // this will not report any gl error but will cause the calling method to return.
+        if (renderbufferObject->getWidth() == 0 || renderbufferObject->getHeight() == 0)
+        {
+            return false;
+        }
+
         renderTargetSerial = renderbufferObject->getSerial();
     }