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      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 
     17 //////////////////////////////////////////////////////////////////////////////
     18 
     19 class GrGLConvexPolyEffect : public GrGLSLFragmentProcessor {
     20 public:
     21     GrGLConvexPolyEffect() {
     22         for (size_t i = 0; i < SK_ARRAY_COUNT(fPrevEdges); ++i) {
     23             fPrevEdges[i] = SK_ScalarNaN;
     24         }
     25     }
     26 
     27     void emitCode(EmitArgs&) override;
     28 
     29     static inline void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder*);
     30 
     31 protected:
     32     void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
     33 
     34 private:
     35     GrGLSLProgramDataManager::UniformHandle fEdgeUniform;
     36     SkScalar                                fPrevEdges[3 * GrConvexPolyEffect::kMaxEdges];
     37     typedef GrGLSLFragmentProcessor INHERITED;
     38 };
     39 
     40 void GrGLConvexPolyEffect::emitCode(EmitArgs& args) {
     41     const GrConvexPolyEffect& cpe = args.fFp.cast<GrConvexPolyEffect>();
     42 
     43     const char *edgeArrayName;
     44     fEdgeUniform = args.fUniformHandler->addUniformArray(kFragment_GrShaderFlag,
     45                                                          kHalf3_GrSLType,
     46                                                          "edges",
     47                                                          cpe.getEdgeCount(),
     48                                                          &edgeArrayName);
     49     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
     50     fragBuilder->codeAppend("\t\thalf alpha = 1.0;\n");
     51     fragBuilder->codeAppend("\t\thalf edge;\n");
     52     for (int i = 0; i < cpe.getEdgeCount(); ++i) {
     53         fragBuilder->codeAppendf("\t\tedge = dot(%s[%d], half3(half(sk_FragCoord.x), "
     54                                                               "half(sk_FragCoord.y), "
     55                                                               "1));\n",
     56                                  edgeArrayName, i);
     57         if (GrProcessorEdgeTypeIsAA(cpe.getEdgeType())) {
     58             fragBuilder->codeAppend("\t\tedge = saturate(edge);\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 
     71 void 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 
     81 void 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 
     91 std::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(SK_PMColor4fWHITE,
    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(SK_PMColor4fTRANSPARENT,
    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 
    162 std::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 
    170 GrConvexPolyEffect::~GrConvexPolyEffect() {}
    171 
    172 void GrConvexPolyEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
    173                                                GrProcessorKeyBuilder* b) const {
    174     GrGLConvexPolyEffect::GenKey(*this, caps, b);
    175 }
    176 
    177 GrGLSLFragmentProcessor* GrConvexPolyEffect::onCreateGLSLInstance() const  {
    178     return new GrGLConvexPolyEffect;
    179 }
    180 
    181 GrConvexPolyEffect::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 
    195 GrConvexPolyEffect::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 
    202 std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::clone() const {
    203     return std::unique_ptr<GrFragmentProcessor>(new GrConvexPolyEffect(*this));
    204 }
    205 
    206 bool 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 
    215 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrConvexPolyEffect);
    216 
    217 #if GR_TEST_UTILS
    218 std::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