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"
12class 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 */
24class GrGeometryProcessor : public GrProcessor {
25public:
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
40protected:
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
51private:
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)                                 \
62static SkAlignedSStorage<sizeof(GP_CLASS)> g_##NAME##_Storage;                                    \
63static GrGeometryProcessor* NAME SkNEW_PLACEMENT_ARGS(g_##NAME##_Storage.get(), GP_CLASS, ARGS);  \
64static SkAutoTDestroy<GrGeometryProcessor> NAME##_ad(NAME);
65
66#endif
67