Disable GL_MULTISAMPLE when it's not being used

Disable GL_MULTISAMPLE when it's not being used

Updates Gr to disable GL_MULTISAMPLE when drawing to an aliased render
target. This is an important step for NV_framebuffer_mixed_samples,
where just because the color buffer isn't multisampled doesn't mean
other stages in the graphics pipeline aren't. It also removes the need
for the "isLineDraw" workaround that was in GrGLGpu::flushHWAAState.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/d0a840d4d8bb6ebc9981cc331b1b231a6c6e0928

[Chris Dalton, 2015-03-14 01:55:48]

cdalton@nvidia.com changed reviewers:
+ vbuzinov@nvidia.com

[Chris Dalton, 2015-03-16 19:53:41]

cdalton@nvidia.com changed reviewers:
+ bsalomon@google.com

[Chris Dalton, 2015-03-16 19:53:41]

This is a prerequisite for https://codereview.chromium.org/1001503002/, which is
nearing completion.

[bsalomon, 2015-03-16 19:58:08]

lgtm

[Chris Dalton, 2015-03-16 23:39:48]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2015-03-16 23:39:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1002013006/1

[commit-bot: I haz the power, 2015-03-16 23:40:00]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-16 23:40:01]

Failed to apply patch for src/gpu/gl/GrGLGpu.cpp:
While running git apply --index -3 -p1;
  error: patch failed: src/gpu/gl/GrGLGpu.cpp:1961
  Falling back to three-way merge...
  Applied patch to 'src/gpu/gl/GrGLGpu.cpp' with conflicts.
  U src/gpu/gl/GrGLGpu.cpp

Patch:       src/gpu/gl/GrGLGpu.cpp
Index: src/gpu/gl/GrGLGpu.cpp
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index
51fc42b9954e154f447ddf2bb14c2608112f1b60..4748961a37cf4c065918b25d174e4a0a1b773dc4
100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -1409,7 +1409,7 @@ void GrGLGpu::flushScissor(const GrScissorState&
scissorState,
     this->disableScissor();
 }
 
-bool GrGLGpu::flushGLState(const DrawArgs& args, bool isLineDraw) {
+bool GrGLGpu::flushGLState(const DrawArgs& args) {
     GrXferProcessor::BlendInfo blendInfo;
     const GrPipeline& pipeline = *args.fPipeline;
     args.fPipeline->getXferProcessor()->getBlendInfo(&blendInfo);
@@ -1441,7 +1441,7 @@ bool GrGLGpu::flushGLState(const DrawArgs& args, bool
isLineDraw) {
     GrGLRenderTarget* glRT =
static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
     this->flushStencil(pipeline.getStencil());
     this->flushScissor(pipeline.getScissorState(), glRT->getViewport(),
glRT->origin());
-    this->flushHWAAState(glRT, pipeline.isHWAntialiasState(), isLineDraw);
+    this->flushHWAAState(glRT, pipeline.isHWAntialiasState());
 
     // This must come after textures are flushed because a texture may need
     // to be msaa-resolved (which will modify bound FBO state).
@@ -1916,7 +1916,7 @@ GrGLenum gPrimitiveType2GLMode[] = {
 #endif
 
 void GrGLGpu::onDraw(const DrawArgs& args, const GrDrawTarget::DrawInfo& info)
{
-    if (!this->flushGLState(args, GrIsPrimTypeLines(info.primitiveType()))) {
+    if (!this->flushGLState(args)) {
         return;
     }
 
@@ -1961,7 +1961,7 @@ void GrGLGpu::onStencilPath(const GrPath* path, const
StencilPathState& state) {
     SkISize size = SkISize::Make(rt->width(), rt->height());
     this->glPathRendering()->setProjectionMatrix(*state.fViewMatrix, size,
rt->origin());
     this->flushScissor(*state.fScissor, rt->getViewport(), rt->origin());
-    this->flushHWAAState(rt, state.fUseHWAA, false);
+    this->flushHWAAState(rt, state.fUseHWAA);
     this->prepareToDrawToRenderTarget(rt, NULL);
 
     fPathRendering->stencilPath(path, *state.fStencil);
@@ -1969,7 +1969,7 @@ void GrGLGpu::onStencilPath(const GrPath* path, const
StencilPathState& state) {
 
 void GrGLGpu::onDrawPath(const DrawArgs& args, const GrPath* path,
                          const GrStencilSettings& stencil) {
-    if (!this->flushGLState(args, false)) {
+    if (!this->flushGLState(args)) {
         return;
     }
     fPathRendering->drawPath(path, stencil);
@@ -1983,7 +1983,7 @@ void GrGLGpu::onDrawPaths(const DrawArgs& args,
                           GrDrawTarget::PathTransformType transformType,
                            int count,
                            const GrStencilSettings& stencil) {
-    if (!this->flushGLState(args, false)) {
+    if (!this->flushGLState(args)) {
         return;
     }
     fPathRendering->drawPaths(pathRange, indices, indexType, transformValues,
@@ -2113,28 +2113,19 @@ void GrGLGpu::flushStencil(const GrStencilSettings&
stencilSettings) {
     }
 }
 
-void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA, bool isLineDraw)
{
-// At least some ATI linux drivers will render GL_LINES incorrectly when MSAA
state is enabled but
-// the target is not multisampled. Single pixel wide lines are rendered thicker
than 1 pixel wide.
-#if 0
-    // Replace RT_HAS_MSAA with this definition once this driver bug is no
longer a relevant concern
-    #define RT_HAS_MSAA rt->isMultisampled()
-#else
-    #define RT_HAS_MSAA (rt->isMultisampled() || isLineDraw)
-#endif
+void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA) {
+    SkASSERT(!useHWAA || rt->isMultisampled());
 
     if (kGL_GrGLStandard == this->glStandard()) {
-        if (RT_HAS_MSAA) {
-            if (useHWAA) {
-                if (kYes_TriState != fMSAAEnabled) {
-                    GL_CALL(Enable(GR_GL_MULTISAMPLE));
-                    fMSAAEnabled = kYes_TriState;
-                }
-            } else {
-                if (kNo_TriState != fMSAAEnabled) {
-                    GL_CALL(Disable(GR_GL_MULTISAMPLE));
-                    fMSAAEnabled = kNo_TriState;
-                }
+        if (useHWAA) {
+            if (kYes_TriState != fMSAAEnabled) {
+                GL_CALL(Enable(GR_GL_MULTISAMPLE));
+                fMSAAEnabled = kYes_TriState;
+            }
+        } else {
+            if (kNo_TriState != fMSAAEnabled) {
+                GL_CALL(Disable(GR_GL_MULTISAMPLE));
+                fMSAAEnabled = kNo_TriState;
             }
         }
     }

[Chris Dalton, 2015-03-17 00:13:41]

The CQ bit was checked by cdalton@nvidia.com

[Chris Dalton, 2015-03-17 00:13:41]

The patchset sent to the CQ was uploaded after l-g-t-m from bsalomon@google.com
Link to the patchset: https://codereview.chromium.org/1002013006/#ps20001
(title: "rebase")

[commit-bot: I haz the power, 2015-03-17 00:14:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1002013006/20001

[commit-bot: I haz the power, 2015-03-17 00:20:06]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/d0a840d4d8bb6ebc9981cc331b1b231a6c6e0928