Set all the drawbuffer state at once instead of one buffer per call.

src/libANGLE/Framebuffer.cpp

@@ -266,9 +266,11 @@ GLenum Framebuffer::getDrawBufferState(unsigned int colorAttachment) const
     return mDrawBufferStates[colorAttachment];
 }
 
-void Framebuffer::setDrawBufferState(unsigned int colorAttachment, GLenum drawBuffer)
+void Framebuffer::setDrawBuffers(size_t count, const GLenum *buffers)
 {
-    mDrawBufferStates[colorAttachment] = drawBuffer;
+    ASSERT(count < ArraySize(mDrawBufferStates));
+    std::copy(buffers, buffers + count, mDrawBufferStates);
+    std::fill(mDrawBufferStates + count, mDrawBufferStates + ArraySize(mDrawBufferStates), GL_NONE);
 }
 
 bool Framebuffer::isEnabledColorAttachment(unsigned int colorAttachment) const

src/libANGLE/Framebuffer.h

@@ -69,7 +69,7 @@ class Framebuffer
     FramebufferAttachment *getAttachment(GLenum attachment) const;
 
     GLenum getDrawBufferState(unsigned int colorAttachment) const;
-    void setDrawBufferState(unsigned int colorAttachment, GLenum drawBuffer);
+    void setDrawBuffers(size_t count, const GLenum *buffers);
 
     bool isEnabledColorAttachment(unsigned int colorAttachment) const;
     bool hasEnabledColorAttachment() const;

src/libGLESv2/libGLESv2.cpp

@@ -8551,15 +8551,7 @@ void GL_APIENTRY glDrawBuffersEXT(GLsizei n, const GLenum *bufs)
         gl::Framebuffer *framebuffer = context->getState().getDrawFramebuffer();
         ASSERT(framebuffer);
 
-        for (unsigned int colorAttachment = 0; colorAttachment < static_cast<unsigned int>(n); colorAttachment++)
-        {
-            framebuffer->setDrawBufferState(colorAttachment, bufs[colorAttachment]);
-        }
-
-        for (unsigned int colorAttachment = n; colorAttachment < context->getCaps().maxDrawBuffers; colorAttachment++)
-        {
-            framebuffer->setDrawBufferState(colorAttachment, GL_NONE);
-        }
+        framebuffer->setDrawBuffers(n, bufs);
     }
 }