Implement NV_path_rendering on OpenGL ES

Implement support for NV_path_rendering on OpenGL ES. Use
glProgramPathFragmentInputGenNV function call instead of glPathTexGenNV to
communicate transforms to fragment shader.

The intention is that the NVPR paths will be drawn with the same shader program
as non-NVPR geometry. For NVPR calls, the GPU will skip the vertex shader and
just run the fragment shader.

After program is linked, query the locations of the fragment shader inputs with
glGetResourceLocation. The location will be used to set the transforms with
glProgramPathFragmentInputGenNV.

The functions and their workings are documented in:

glProgramPathFragmentInputGenNV
https://www.opengl.org/registry/specs/NV/path_rendering.txt
(note: addition as of API version 1.3)

glGetResourceLocation
https://www.opengl.org/registry/specs/ARB/program_interface_query.txt
http://www.opengl.org/registry/doc/glspec44.core.pdf
(function is in core Open GL 4.4)

Note: glProgramPathFragmentInputGenNV could be used also for OpenGL. However,
using seems to trigger a bug in the driver. Disable this feature on OpenGL at
least until the driver is fixed and released. The bug manifests in shadertext
test, where the lower-left text pair is missing. Valgrind catches a bad read
for the test and causes the context to OOM reproducibly.

R=bsalomon@google.com, cdalton@nvidia.com, joshualitt@google.com, joshualitt@chromium.org

Author: kkinnunen@nvidia.com

Review URL: https://codereview.chromium.org/367643004

1 files changed, 5 insertions, 5 deletions

diff --git a/include/gpu/GrEffect.h b/include/gpu/GrEffect.h
index 4734c7c377..09d716f80a 100644
--- a/include/gpu/GrEffect.h
+++ b/include/gpu/GrEffect.h
@@ -114,10 +114,10 @@ public:
 
     /** Will this effect emit custom vertex shader code?
         (To set this value the effect must inherit from GrEffect.) */
-    bool hasVertexCode() const { return fHasVertexCode; }
+    bool requiresVertexShader() const { return fRequiresVertexShader; }
 
     int numVertexAttribs() const {
-        SkASSERT(0 == fVertexAttribTypes.count() || fHasVertexCode);
+        SkASSERT(0 == fVertexAttribTypes.count() || fRequiresVertexShader);
         return fVertexAttribTypes.count();
     }
 
@@ -166,7 +166,7 @@ protected:
         : fWillReadDstColor(false)
         , fWillReadFragmentPosition(false)
         , fWillUseInputColor(true)
-        , fHasVertexCode(false) {}
+        , fRequiresVertexShader(false) {}
 
     /**
       * Helper for down-casting to a GrEffect subclass
@@ -204,7 +204,7 @@ private:
         getFactory()).*/
     virtual bool onIsEqual(const GrEffect& other) const = 0;
 
-    friend class GrVertexEffect; // to set fHasVertexCode and build fVertexAttribTypes.
+    friend class GrVertexEffect; // to set fRequiresVertexShader and build fVertexAttribTypes.
 
     SkSTArray<4, const GrCoordTransform*, true>  fCoordTransforms;
     SkSTArray<4, const GrTextureAccess*, true>   fTextureAccesses;
@@ -212,7 +212,7 @@ private:
     bool                                         fWillReadDstColor;
     bool                                         fWillReadFragmentPosition;
     bool                                         fWillUseInputColor;
-    bool                                         fHasVertexCode;
+    bool                                         fRequiresVertexShader;
 
     typedef SkRefCnt INHERITED;
 };