commit 588434c4d869e0591db758b1ceb447e2308b09d1
author Austin Kinross <aukinros@microsoft.com> Wed Dec 10 10:41:45 2014 -0800
committer Jamie Madill <jmadill@chromium.org> Fri Dec 12 15:01:50 2014 +0000
tree 3e5e6a78a39d5a3d1df5f91df91490099b210fa8
parent 492a7e43ebdd2c40e8b6e7b5cd961065069a2cff

Prevent D3D11 Feature Level 9_3 from sampling from SV_Position in Pixel Shaders

D3D11 FL9_3, like Shader Model 2.0 in D3D9, doesn't support reading from SV_Position in the pixel shader. We have to reconstruct gl_FragCoord using dx_ViewCoords instead.

Change-Id: I7e898038d210d73a9d224dcc18b033e5cd4a56f5
Reviewed-on: https://chromium-review.googlesource.com/234277
Tested-by: Austin Kinross <aukinros@microsoft.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/libANGLE/renderer/d3d/DynamicHLSL.cpp

diff --git a/src/libANGLE/renderer/d3d/DynamicHLSL.cpp b/src/libANGLE/renderer/d3d/DynamicHLSL.cpp
index 8e0c2bd..1225f58 100644
--- a/src/libANGLE/renderer/d3d/DynamicHLSL.cpp
+++ b/src/libANGLE/renderer/d3d/DynamicHLSL.cpp
@@ -871,12 +871,14 @@
     {
         pixelHLSL += "    float rhw = 1.0 / input.gl_FragCoord.w;\n";
 
-        if (shaderModel >= 4)
+        // Certain Shader Models (4_0+ and 3_0) allow reading from dx_Position in the pixel shader.
+        // Other Shader Models (4_0_level_9_3 and 2_x) don't support this, so we emulate it using dx_ViewCoords.
+        if (shaderModel >= 4 && mRenderer->getShaderModelSuffix() == "")
         {
             pixelHLSL += "    gl_FragCoord.x = input.dx_Position.x;\n"
                          "    gl_FragCoord.y = input.dx_Position.y;\n";
         }
-        else if (shaderModel >= 3)
+        else if (shaderModel == 3)
         {
             pixelHLSL += "    gl_FragCoord.x = input.dx_Position.x + 0.5;\n"
                          "    gl_FragCoord.y = input.dx_Position.y + 0.5;\n";