1/*
2 * Copyright 2014 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#include "GrConvexPolyEffect.h"
9#include "SkPathPriv.h"
10#include "effects/GrAARectEffect.h"
11#include "effects/GrConstColorProcessor.h"
12#include "glsl/GrGLSLFragmentProcessor.h"
13#include "glsl/GrGLSLFragmentShaderBuilder.h"
14#include "glsl/GrGLSLProgramDataManager.h"
15#include "glsl/GrGLSLUniformHandler.h"
16#include "../private/GrGLSL.h"
17
18//////////////////////////////////////////////////////////////////////////////
19
20class GrGLConvexPolyEffect : public GrGLSLFragmentProcessor {
21public:
22    GrGLConvexPolyEffect() {
23        for (size_t i = 0; i < SK_ARRAY_COUNT(fPrevEdges); ++i) {
24            fPrevEdges[i] = SK_ScalarNaN;
25        }
26    }
27
28    void emitCode(EmitArgs&) override;
29
30    static inline void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder*);
31
32protected:
33    void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
34
35private:
36    GrGLSLProgramDataManager::UniformHandle fEdgeUniform;
37    SkScalar                                fPrevEdges[3 * GrConvexPolyEffect::kMaxEdges];
38    typedef GrGLSLFragmentProcessor INHERITED;
39};
40
41void GrGLConvexPolyEffect::emitCode(EmitArgs& args) {
42    const GrConvexPolyEffect& cpe = args.fFp.cast<GrConvexPolyEffect>();
43
44    const char *edgeArrayName;
45    fEdgeUniform = args.fUniformHandler->addUniformArray(kFragment_GrShaderFlag,
46                                                         kHalf3_GrSLType,
47                                                         "edges",
48                                                         cpe.getEdgeCount(),
49                                                         &edgeArrayName);
50    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
51    fragBuilder->codeAppend("\t\thalf alpha = 1.0;\n");
52    fragBuilder->codeAppend("\t\thalf edge;\n");
53    for (int i = 0; i < cpe.getEdgeCount(); ++i) {
54        fragBuilder->codeAppendf("\t\tedge = dot(%s[%d], half3(sk_FragCoord.x, sk_FragCoord.y, "
55                                                             "1));\n",
56                                 edgeArrayName, i);
57        if (GrProcessorEdgeTypeIsAA(cpe.getEdgeType())) {
58            fragBuilder->codeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
59        } else {
60            fragBuilder->codeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
61        }
62        fragBuilder->codeAppend("\t\talpha *= edge;\n");
63    }
64
65    if (GrProcessorEdgeTypeIsInverseFill(cpe.getEdgeType())) {
66        fragBuilder->codeAppend("\talpha = 1.0 - alpha;\n");
67    }
68    fragBuilder->codeAppendf("\t%s = %s * alpha;\n", args.fOutputColor, args.fInputColor);
69}
70
71void GrGLConvexPolyEffect::onSetData(const GrGLSLProgramDataManager& pdman,
72                                     const GrFragmentProcessor& effect) {
73    const GrConvexPolyEffect& cpe = effect.cast<GrConvexPolyEffect>();
74    size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
75    if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
76        pdman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
77        memcpy(fPrevEdges, cpe.getEdges(), byteSize);
78    }
79}
80
81void GrGLConvexPolyEffect::GenKey(const GrProcessor& processor, const GrShaderCaps&,
82                                  GrProcessorKeyBuilder* b) {
83    const GrConvexPolyEffect& cpe = processor.cast<GrConvexPolyEffect>();
84    GR_STATIC_ASSERT(kGrClipEdgeTypeCnt <= 8);
85    uint32_t key = (cpe.getEdgeCount() << 3) | (int) cpe.getEdgeType();
86    b->add32(key);
87}
88
89//////////////////////////////////////////////////////////////////////////////
90
91std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::Make(GrClipEdgeType type,
92                                                              const SkPath& path) {
93    if (GrClipEdgeType::kHairlineAA == type) {
94        return nullptr;
95    }
96    if (path.getSegmentMasks() != SkPath::kLine_SegmentMask ||
97        !path.isConvex()) {
98        return nullptr;
99    }
100
101    SkPathPriv::FirstDirection dir;
102    // The only way this should fail is if the clip is effectively a infinitely thin line. In that
103    // case nothing is inside the clip. It'd be nice to detect this at a higher level and either
104    // skip the draw or omit the clip element.
105    if (!SkPathPriv::CheapComputeFirstDirection(path, &dir)) {
106        if (GrProcessorEdgeTypeIsInverseFill(type)) {
107            return GrConstColorProcessor::Make(GrColor4f::OpaqueWhite(),
108                                               GrConstColorProcessor::InputMode::kModulateRGBA);
109        }
110        // This could use kIgnore instead of kModulateRGBA but it would trigger a debug print
111        // about a coverage processor not being compatible with the alpha-as-coverage optimization.
112        // We don't really care about this unlikely case so we just use kModulateRGBA to suppress
113        // the print.
114        return GrConstColorProcessor::Make(GrColor4f::TransparentBlack(),
115                                           GrConstColorProcessor::InputMode::kModulateRGBA);
116    }
117
118    SkScalar        edges[3 * kMaxEdges];
119    SkPoint         pts[4];
120    SkPath::Verb    verb;
121    SkPath::Iter    iter(path, true);
122
123    // SkPath considers itself convex so long as there is a convex contour within it,
124    // regardless of any degenerate contours such as a string of moveTos before it.
125    // Iterate here to consume any degenerate contours and only process the points
126    // on the actual convex contour.
127    int n = 0;
128    while ((verb = iter.next(pts, true, true)) != SkPath::kDone_Verb) {
129        switch (verb) {
130            case SkPath::kMove_Verb:
131                SkASSERT(n == 0);
132            case SkPath::kClose_Verb:
133                break;
134            case SkPath::kLine_Verb: {
135                if (n >= kMaxEdges) {
136                    return nullptr;
137                }
138                SkVector v = pts[1] - pts[0];
139                v.normalize();
140                if (SkPathPriv::kCCW_FirstDirection == dir) {
141                    edges[3 * n] = v.fY;
142                    edges[3 * n + 1] = -v.fX;
143                } else {
144                    edges[3 * n] = -v.fY;
145                    edges[3 * n + 1] = v.fX;
146                }
147                edges[3 * n + 2] = -(edges[3 * n] * pts[1].fX + edges[3 * n + 1] * pts[1].fY);
148                ++n;
149                break;
150            }
151            default:
152                return nullptr;
153        }
154    }
155
156    if (path.isInverseFillType()) {
157        type = GrInvertProcessorEdgeType(type);
158    }
159    return Make(type, n, edges);
160}
161
162std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::Make(GrClipEdgeType edgeType,
163                                                              const SkRect& rect) {
164    if (GrClipEdgeType::kHairlineAA == edgeType){
165        return nullptr;
166    }
167    return GrAARectEffect::Make(edgeType, rect);
168}
169
170GrConvexPolyEffect::~GrConvexPolyEffect() {}
171
172void GrConvexPolyEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
173                                               GrProcessorKeyBuilder* b) const {
174    GrGLConvexPolyEffect::GenKey(*this, caps, b);
175}
176
177GrGLSLFragmentProcessor* GrConvexPolyEffect::onCreateGLSLInstance() const  {
178    return new GrGLConvexPolyEffect;
179}
180
181GrConvexPolyEffect::GrConvexPolyEffect(GrClipEdgeType edgeType, int n, const SkScalar edges[])
182        : INHERITED(kGrConvexPolyEffect_ClassID, kCompatibleWithCoverageAsAlpha_OptimizationFlag)
183        , fEdgeType(edgeType)
184        , fEdgeCount(n) {
185    // Factory function should have already ensured this.
186    SkASSERT(n <= kMaxEdges);
187    memcpy(fEdges, edges, 3 * n * sizeof(SkScalar));
188    // Outset the edges by 0.5 so that a pixel with center on an edge is 50% covered in the AA case
189    // and 100% covered in the non-AA case.
190    for (int i = 0; i < n; ++i) {
191        fEdges[3 * i + 2] += SK_ScalarHalf;
192    }
193}
194
195GrConvexPolyEffect::GrConvexPolyEffect(const GrConvexPolyEffect& that)
196        : INHERITED(kGrConvexPolyEffect_ClassID, kCompatibleWithCoverageAsAlpha_OptimizationFlag)
197        , fEdgeType(that.fEdgeType)
198        , fEdgeCount(that.fEdgeCount) {
199    memcpy(fEdges, that.fEdges, 3 * that.fEdgeCount * sizeof(SkScalar));
200}
201
202std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::clone() const {
203    return std::unique_ptr<GrFragmentProcessor>(new GrConvexPolyEffect(*this));
204}
205
206bool GrConvexPolyEffect::onIsEqual(const GrFragmentProcessor& other) const {
207    const GrConvexPolyEffect& cpe = other.cast<GrConvexPolyEffect>();
208    // ignore the fact that 0 == -0 and just use memcmp.
209    return (cpe.fEdgeType == fEdgeType && cpe.fEdgeCount == fEdgeCount &&
210            0 == memcmp(cpe.fEdges, fEdges, 3 * fEdgeCount * sizeof(SkScalar)));
211}
212
213//////////////////////////////////////////////////////////////////////////////
214
215GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrConvexPolyEffect);
216
217#if GR_TEST_UTILS
218std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::TestCreate(GrProcessorTestData* d) {
219    int count = d->fRandom->nextULessThan(kMaxEdges) + 1;
220    SkScalar edges[kMaxEdges * 3];
221    for (int i = 0; i < 3 * count; ++i) {
222        edges[i] = d->fRandom->nextSScalar1();
223    }
224
225    std::unique_ptr<GrFragmentProcessor> fp;
226    do {
227        GrClipEdgeType edgeType = static_cast<GrClipEdgeType>(
228                d->fRandom->nextULessThan(kGrClipEdgeTypeCnt));
229        fp = GrConvexPolyEffect::Make(edgeType, count, edges);
230    } while (nullptr == fp);
231    return fp;
232}
233#endif
234