Implement support for mixed sampled render targets

include/gpu/GrTypes.h

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTypes_DEFINED
 #define GrTypes_DEFINED
@@ skipping 405 matching lines @@
  * to BottomLeft.
  */
 
 enum GrSurfaceOrigin {
     kDefault_GrSurfaceOrigin,         // DEPRECATED; to be removed
     kTopLeft_GrSurfaceOrigin,
     kBottomLeft_GrSurfaceOrigin,
 };
 
 /**
+ * Sample config clarifies the meaning of samples count.
+ * In default kUnified_GrSampleConfig sample count refers to MSAA sample count.
+ * If NV_framebuffer_mixed_samples is available and sample config is chosen to be
+ * kStencil_GrSampleConfig, sample count refers to the stencil sample count only,
+ * and the color sample count is assumed to be zero.
+ */
+enum GrSampleConfig {
+    kUnified_GrSampleConfig,
+    kStencil_GrSampleConfig,
+};
+
+/**
  * Describes a surface to be created.
  */
 struct GrSurfaceDesc {
     GrSurfaceDesc()
     : fFlags(kNone_GrSurfaceFlags)
     , fOrigin(kDefault_GrSurfaceOrigin)
     , fWidth(0)
     , fHeight(0)
     , fConfig(kUnknown_GrPixelConfig)
     , fSampleCnt(0) {
@@ skipping 106 matching lines @@
     int                             fWidth;         //<! width in pixels
     int                             fHeight;        //<! height in pixels
     GrPixelConfig                   fConfig;        //<! color format
     GrSurfaceOrigin                 fOrigin;        //<! pixel origin
     /**
      * The number of samples per pixel. Gr uses this to influence decisions
      * about applying other forms of anti-aliasing.
      */
     int                             fSampleCnt;
     /**
+     * If fSampleCnt is > 1, which buffers are multisampled (color and stencil,
+     * or just stencil?). The default is both. Note that mixing multisampled
+     * and aliased buffers is only possible if NV_framebuffer_mixed_samples is
+     * available.
+     */
+    GrSampleConfig                  fSampleConfig;

[bsalomon, 2015/03/31 16:37:33]

Maybe just have a flag in fFlags? kStencilMSAAOnly_GrSurfaceFlag?

[Chris Dalton, 2015/03/31 22:24:57]

I don't see an fFlags field for GrBackendRenderTargetDesc, should we add one,
along with a GrBackendRenderTargetFlags enum? I really like that, and it also
lets us move GrSampleConfig out of this file and into GrRenderTarget.

+    /**
      * Number of bits of stencil per-pixel.
      */
     int                             fStencilBits;
     /**
      * Handle to the 3D API object.
      * OpenGL: FBO ID
      */
     GrBackendObject                 fRenderTargetHandle;
 };
 
@@ skipping 64 matching lines @@
 public:
     GrAutoMalloc() : INHERITED() {}
     explicit GrAutoMalloc(size_t size) : INHERITED(size) {}
     virtual ~GrAutoMalloc() {}
 private:
     typedef GrAutoMallocBaseType INHERITED;
 };
 
 #undef GrAutoMallocBaseType
 #endif