Enable stencil clipping in mixed sampled render targets

src/gpu/gl/GrGLGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 238 matching lines @@
 
     void initFSAASupport();
 
     // determines valid stencil formats
     void initStencilFormats();
 
     // sets a texture unit to use for texture operations other than binding a texture to a program.
     // ensures that such operations don't negatively interact with tracking bound textures.
     void setScratchTextureUnit();
 
+    // enables or disables programmable sample locations for render target, if MSAA.
+    // allows overriding default sample locations used by hardware.
+    void setProgrammableSampleLocations(GrRenderTarget* rt, bool useSampleLocations);

[Chris Dalton, 2015/09/22 08:35:24]

I wonder if this should have a different name, since its actual purpose seems to
be enabling centered, co-located sample positions?

Either that, or this method accepts an array of sample positions and the caller
supplies centered locdations (or whatever it wants).

+
     // bounds is region that may be modified and therefore has to be resolved.
     // nullptr means whole target. Can be an empty rect.
     void flushRenderTarget(GrGLRenderTarget*, const SkIRect* bounds);
 
     void flushStencil(const GrStencilSettings&);
     void flushHWAAState(GrRenderTarget* rt, bool useHWAA);
 
     bool configToGLFormats(GrPixelConfig config,
                            bool getSizedInternal,
                            GrGLenum* internalFormat,
@@ skipping 229 matching lines @@
 
     // Mapping of pixel configs to known supported stencil formats to be used
     // when adding a stencil buffer to a framebuffer.
     int fPixelConfigToStencilIndex[kGrPixelConfigCnt];
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif