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      1 /*
      2  * Copyright 2013 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrGeometryProcessor_DEFINED
      9 #define GrGeometryProcessor_DEFINED
     10 
     11 #include "GrProcessor.h"
     12 class GrBackendGeometryProcessorFactory;
     13 
     14 /**
     15  * A GrGeomteryProcessor is used to perform computation in the vertex shader and
     16  * add support for custom vertex attributes. A GrGemeotryProcessor is typically
     17  * tied to the code that does a specific type of high-level primitive rendering
     18  * (e.g. anti-aliased circle rendering). The GrGeometryProcessor used for a draw is
     19  * specified using GrDrawState. There can only be one geometry processor active for
     20  * a draw. The custom vertex attributes required by the geometry processor must be
     21  * added to the vertex attribute array specified on the GrDrawState.
     22  * GrGeometryProcessor subclasses should be immutable after construction.
     23  */
     24 class GrGeometryProcessor : public GrProcessor {
     25 public:
     26     GrGeometryProcessor() {}
     27 
     28     virtual const GrBackendGeometryProcessorFactory& getFactory() const = 0;
     29 
     30     /*
     31      * This only has a max because GLProgramsTest needs to generate test arrays, and these have to
     32      * be static
     33      * TODO make this truly dynamic
     34      */
     35     static const int kMaxVertexAttribs = 2;
     36     typedef SkTArray<GrShaderVar, true> VertexAttribArray;
     37 
     38     const VertexAttribArray& getVertexAttribs() const { return fVertexAttribs; }
     39 
     40 protected:
     41     /**
     42      * Subclasses call this from their constructor to register vertex attributes (at most
     43      * kMaxVertexAttribs). This must only be called from the constructor because GrProcessors are
     44      * immutable.
     45      */
     46     const GrShaderVar& addVertexAttrib(const GrShaderVar& var) {
     47         SkASSERT(fVertexAttribs.count() < kMaxVertexAttribs);
     48         return fVertexAttribs.push_back(var);
     49     }
     50 
     51 private:
     52     SkSTArray<kMaxVertexAttribs, GrShaderVar, true> fVertexAttribs;
     53 
     54     typedef GrProcessor INHERITED;
     55 };
     56 
     57 /**
     58  * This creates an effect outside of the effect memory pool. The effect's destructor will be called
     59  * at global destruction time. NAME will be the name of the created GrProcessor.
     60  */
     61 #define GR_CREATE_STATIC_GEOMETRY_PROCESSOR(NAME, GP_CLASS, ARGS)                                 \
     62 static SkAlignedSStorage<sizeof(GP_CLASS)> g_##NAME##_Storage;                                    \
     63 static GrGeometryProcessor* NAME SkNEW_PLACEMENT_ARGS(g_##NAME##_Storage.get(), GP_CLASS, ARGS);  \
     64 static SkAutoTDestroy<GrGeometryProcessor> NAME##_ad(NAME);
     65 
     66 #endif
     67