In Clear11, use ID3D11DeviceContext1::ClearView when appropriate

src/libANGLE/renderer/d3d/d3d11/Clear11.cpp

@@ -150,15 +150,19 @@ Clear11::~Clear11()
 
 gl::Error Clear11::clearFramebuffer(const gl::ClearParameters &clearParams, const gl::Framebuffer *frameBuffer)
 {
-    // First determine if a scissored clear is needed, this will always require drawing a quad.
-    //
-    // Otherwise, iterate over the color buffers which require clearing and determine if they can be
-    // cleared with ID3D11DeviceContext::ClearRenderTargetView... This requires:
+    // Iterate over the color buffers which require clearing and determine if they can be
+    // cleared with ID3D11DeviceContext::ClearRenderTargetView or ID3D11DeviceContext1::ClearView.
+    // This requires:
     // 1) The render target is being cleared to a float value (will be cast to integer when clearing integer
     //    render targets as expected but does not work the other way around)
     // 2) The format of the render target has no color channels that are currently masked out.
     // Clear the easy-to-clear buffers on the spot and accumulate the ones that require special work.
     //
+    // If these conditions are met, and:
+    // - No scissored clear is needed, then clear using ID3D11DeviceContext::ClearRenderTargetView.
+    // - A scissored clear is needed then clear using ID3D11DeviceContext1::ClearView if available.
+    //   Otherwise draw a quad.
+    //
     // Also determine if the depth stencil can be cleared with ID3D11DeviceContext::ClearDepthStencilView
     // by checking if the stencil write mask covers the entire stencil.
     //
@@ -203,6 +207,7 @@ gl::Error Clear11::clearFramebuffer(const gl::ClearParameters &clearParams, cons
     RenderTarget11* maskedClearDepthStencil = NULL;
 
     ID3D11DeviceContext *deviceContext = mRenderer->getDeviceContext();
+    ID3D11DeviceContext1 *deviceContext1 = mRenderer->getDeviceContext1IfSupported();
 
     for (unsigned int colorAttachment = 0; colorAttachment < gl::IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
     {
@@ -236,13 +241,13 @@ gl::Error Clear11::clearFramebuffer(const gl::ClearParameters &clearParams, cons
                     // Every channel either does not exist in the render target or is masked out
                     continue;
                 }
-                else if (needScissoredClear || clearParams.colorClearType != GL_FLOAT ||
+                else if ((!deviceContext1 && needScissoredClear) || clearParams.colorClearType != GL_FLOAT ||
                          (formatInfo.redBits   > 0 && !clearParams.colorMaskRed)   ||
                          (formatInfo.greenBits > 0 && !clearParams.colorMaskGreen) ||
                          (formatInfo.blueBits  > 0 && !clearParams.colorMaskBlue) ||
                          (formatInfo.alphaBits > 0 && !clearParams.colorMaskAlpha))
                 {
-                    // A scissored or masked clear is required
+                    // A masked clear is required, or a scissored clear is required and ID3D11DeviceContext1::ClearView is unavailable
                     MaskedRenderTarget maskAndRt;
                     bool clearColor = clearParams.clearColor[colorAttachment];
                     maskAndRt.colorMask[0] = (clearColor && clearParams.colorMaskRed);
@@ -254,7 +259,7 @@ gl::Error Clear11::clearFramebuffer(const gl::ClearParameters &clearParams, cons
                 }
                 else
                 {
-                    // ID3D11DeviceContext::ClearRenderTargetView is possible
+                    // ID3D11DeviceContext::ClearRenderTargetView or ID3D11DeviceContext1::ClearView is possible
 
                     ID3D11RenderTargetView *framebufferRTV = renderTarget->getRenderTargetView();
                     if (!framebufferRTV)
@@ -274,7 +279,23 @@ gl::Error Clear11::clearFramebuffer(const gl::ClearParameters &clearParams, cons
                         ((formatInfo.alphaBits == 0 && actualFormatInfo.alphaBits > 0) ? 1.0f : clearParams.colorFClearValue.alpha),
                     };
 
-                    deviceContext->ClearRenderTargetView(framebufferRTV, clearValues);
+                    if (needScissoredClear)
+                    {
+                        // We shouldn't reach here if deviceContext1 is unavailable.
+                        ASSERT(deviceContext1);
+
+                        D3D11_RECT rect;
+                        rect.left = clearParams.scissor.x;
+                        rect.right = clearParams.scissor.x + clearParams.scissor.width;
+                        rect.top = clearParams.scissor.y;
+                        rect.bottom = clearParams.scissor.y + clearParams.scissor.height;
+
+                        deviceContext1->ClearView(framebufferRTV, clearValues, &rect, 1);
+                    }
+                    else
+                    {
+                        deviceContext->ClearRenderTargetView(framebufferRTV, clearValues);
+                    }
                 }
             }
         }

src/libANGLE/renderer/d3d/d3d11/Renderer11.cpp

@@ -178,6 +178,7 @@ Renderer11::Renderer11(egl::Display *display, EGLNativeDisplayType hDc, const eg
 
     mDevice = NULL;
     mDeviceContext = NULL;
+    mDeviceContext1 = NULL;
     mDxgiAdapter = NULL;
     mDxgiFactory = NULL;
 
@@ -330,6 +331,11 @@ EGLint Renderer11::initialize()
 #endif
 #endif
 
+    // Cast the DeviceContext to a DeviceContext1.
+    // This could fail on Windows 7 without the Platform Update.
+    // Don't error in this case- just don't use mDeviceContext1.
+    mDeviceContext1 = d3d11::DynamicCastComObject<ID3D11DeviceContext1>(mDeviceContext);
+
     IDXGIDevice *dxgiDevice = NULL;
     result = mDevice->QueryInterface(__uuidof(IDXGIDevice), (void**)&dxgiDevice);
 
@@ -1894,6 +1900,8 @@ void Renderer11::release()
     SafeRelease(mDxgiFactory);
     SafeRelease(mDxgiAdapter);
 
+    SafeRelease(mDeviceContext1);
+
     if (mDeviceContext)
     {
         mDeviceContext->ClearState();

src/libANGLE/renderer/d3d/d3d11/Renderer11.h

@@ -188,6 +188,7 @@ class Renderer11 : public RendererD3D
     // D3D11-renderer specific methods
     ID3D11Device *getDevice() { return mDevice; }
     ID3D11DeviceContext *getDeviceContext() { return mDeviceContext; };
+    ID3D11DeviceContext1 *getDeviceContext1IfSupported() { return mDeviceContext1; };
     DXGIFactory *getDxgiFactory() { return mDxgiFactory; };
 
     Blit11 *getBlitter() { return mBlit; }
@@ -361,6 +362,7 @@ class Renderer11 : public RendererD3D
     ID3D11Device *mDevice;
     D3D_FEATURE_LEVEL mFeatureLevel;
     ID3D11DeviceContext *mDeviceContext;
+    ID3D11DeviceContext1 *mDeviceContext1;
     IDXGIAdapter *mDxgiAdapter;
     DXGI_ADAPTER_DESC mAdapterDescription;
     char mDescription[128];