From a5aacc9cad5d49690b4f83b94b179d865205df6a Mon Sep 17 00:00:00 2001
From: Stephen White <senorblanco@chromium.org>
Date: Thu, 1 Mar 2018 15:41:48 -0500
Subject: [PATCH] Fix color write mask on GL backend.

Set the color mask even if blending is disabled.
---
 src/backend/opengl/BlendStateGL.cpp   |  8 ++++----
 src/tests/end2end/BlendStateTests.cpp | 26 ++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/backend/opengl/BlendStateGL.cpp b/src/backend/opengl/BlendStateGL.cpp
index d1ead39f25..42d981e905 100644
--- a/src/backend/opengl/BlendStateGL.cpp
+++ b/src/backend/opengl/BlendStateGL.cpp
@@ -85,13 +85,13 @@ namespace backend { namespace opengl {
                                  GLBlendFactor(info.colorBlend.dstFactor, false),
                                  GLBlendFactor(info.alphaBlend.srcFactor, true),
                                  GLBlendFactor(info.alphaBlend.dstFactor, true));
-            glColorMaski(attachment, info.colorWriteMask & nxt::ColorWriteMask::Red,
-                         info.colorWriteMask & nxt::ColorWriteMask::Green,
-                         info.colorWriteMask & nxt::ColorWriteMask::Blue,
-                         info.colorWriteMask & nxt::ColorWriteMask::Alpha);
         } else {
             glDisablei(GL_BLEND, attachment);
         }
+        glColorMaski(attachment, info.colorWriteMask & nxt::ColorWriteMask::Red,
+                     info.colorWriteMask & nxt::ColorWriteMask::Green,
+                     info.colorWriteMask & nxt::ColorWriteMask::Blue,
+                     info.colorWriteMask & nxt::ColorWriteMask::Alpha);
     }
 
 }}  // namespace backend::opengl
diff --git a/src/tests/end2end/BlendStateTests.cpp b/src/tests/end2end/BlendStateTests.cpp
index dc65297d1d..56a780cc6c 100644
--- a/src/tests/end2end/BlendStateTests.cpp
+++ b/src/tests/end2end/BlendStateTests.cpp
@@ -667,6 +667,32 @@ TEST_P(BlendStateTest, ColorWriteMask) {
     }
 }
 
+// Check that the color write mask works when blending is disabled
+TEST_P(BlendStateTest, ColorWriteMaskBlendingDisabled) {
+    {
+        nxt::BlendState blendState = device.CreateBlendStateBuilder()
+            .SetBlendEnabled(false)
+            .SetColorWriteMask(nxt::ColorWriteMask::Red)
+            .GetResult();
+        SetupSingleSourcePipelines(blendState);
+
+        RGBA8 base(32, 64, 128, 192);
+        RGBA8 expected(32, 0, 0, 0);
+        nxt::CommandBuffer commands = device.CreateCommandBufferBuilder()
+            .BeginRenderPass(fb.renderPass, fb.framebuffer)
+            .BeginRenderSubpass()
+                .SetRenderPipeline(testPipeline)
+                .SetBindGroup(0, MakeBindGroupForColors(std::array<RGBA8, 1>({ { base } })))
+                .DrawArrays(3, 1, 0, 0)
+            .EndRenderSubpass()
+            .EndRenderPass()
+            .GetResult();
+
+        queue.Submit(1, &commands);
+        EXPECT_PIXEL_RGBA8_EQ(expected, fb.color, kRTSize / 2, kRTSize / 2);
+    }
+}
+
 // Test that independent blend states on render targets works
 TEST_P(BlendStateTest, IndependentBlendState) {