1 /* 2 * Copyright 2017 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 GrGrCCFillGeometry_DEFINED 9 #define GrGrCCFillGeometry_DEFINED 10 11 #include "SkGeometry.h" 12 #include "SkNx.h" 13 #include "SkPoint.h" 14 #include "SkTArray.h" 15 16 /** 17 * This class chops device-space contours up into a series of segments that CCPR knows how to 18 * fill. (See GrCCFillGeometry::Verb.) 19 * 20 * NOTE: This must be done in device space, since an affine transformation can change whether a 21 * curve is monotonic. 22 */ 23 class GrCCFillGeometry { 24 public: 25 // These are the verbs that CCPR knows how to fill. If a path has any segments that don't map to 26 // this list, then they are chopped into smaller ones that do. A list of these comprise a 27 // compact representation of what can later be expanded into GPU instance data. 28 enum class Verb : uint8_t { 29 kBeginPath, // Included only for caller convenience. 30 kBeginContour, 31 kLineTo, 32 kMonotonicQuadraticTo, // Monotonic relative to the vector between its endpoints [P2 - P0]. 33 kMonotonicCubicTo, 34 kMonotonicConicTo, 35 kEndClosedContour, // endPt == startPt. 36 kEndOpenContour // endPt != startPt. 37 }; 38 39 // These tallies track numbers of CCPR primitives that are required to draw a contour. 40 struct PrimitiveTallies { 41 int fTriangles; // Number of triangles in the contour's fan. 42 int fWeightedTriangles; // Triangles (from the tessellator) whose winding magnitude > 1. 43 int fQuadratics; 44 int fCubics; 45 int fConics; 46 47 void operator+=(const PrimitiveTallies&); 48 PrimitiveTallies operator-(const PrimitiveTallies&) const; 49 bool operator==(const PrimitiveTallies&); 50 }; 51 52 GrCCFillGeometry(int numSkPoints = 0, int numSkVerbs = 0, int numConicWeights = 0) 53 : fPoints(numSkPoints * 3) // Reserve for a 3x expansion in points and verbs. 54 , fVerbs(numSkVerbs * 3) 55 , fConicWeights(numConicWeights * 3/2) {} 56 points()57 const SkTArray<SkPoint, true>& points() const { SkASSERT(!fBuildingContour); return fPoints; } verbs()58 const SkTArray<Verb, true>& verbs() const { SkASSERT(!fBuildingContour); return fVerbs; } getConicWeight(int idx)59 float getConicWeight(int idx) const { SkASSERT(!fBuildingContour); return fConicWeights[idx]; } 60 reset()61 void reset() { 62 SkASSERT(!fBuildingContour); 63 fPoints.reset(); 64 fVerbs.reset(); 65 } 66 67 void beginPath(); 68 void beginContour(const SkPoint&); 69 void lineTo(const SkPoint P[2]); 70 void quadraticTo(const SkPoint[3]); 71 72 // We pass through inflection points and loop intersections using a line and quadratic(s) 73 // respectively. 'inflectPad' and 'loopIntersectPad' specify how close (in pixels) cubic 74 // segments are allowed to get to these points. For normal rendering you will want to use the 75 // default values, but these can be overridden for testing purposes. 76 // 77 // NOTE: loops do appear to require two full pixels of padding around the intersection point. 78 // With just one pixel-width of pad, we start to see bad pixels. Ultimately this has a 79 // minimal effect on the total amount of segments produced. Most sections that pass 80 // through the loop intersection can be approximated with a single quadratic anyway, 81 // regardless of whether we are use one pixel of pad or two (1.622 avg. quads per loop 82 // intersection vs. 1.489 on the tiger). 83 void cubicTo(const SkPoint[4], float inflectPad = 0.55f, float loopIntersectPad = 2); 84 85 void conicTo(const SkPoint[3], float w); 86 87 PrimitiveTallies endContour(); // Returns the numbers of primitives needed to draw the contour. 88 89 private: 90 inline void appendLine(const Sk2f& p0, const Sk2f& p1); 91 92 inline void appendQuadratics(const Sk2f& p0, const Sk2f& p1, const Sk2f& p2); 93 inline void appendMonotonicQuadratic(const Sk2f& p0, const Sk2f& p1, const Sk2f& p2); 94 95 enum class AppendCubicMode : bool { 96 kLiteral, 97 kApproximate 98 }; 99 void appendCubics(AppendCubicMode, const Sk2f& p0, const Sk2f& p1, const Sk2f& p2, 100 const Sk2f& p3, const float chops[], int numChops, float localT0 = 0, 101 float localT1 = 1); 102 void appendCubics(AppendCubicMode, const Sk2f& p0, const Sk2f& p1, const Sk2f& p2, 103 const Sk2f& p3, int maxSubdivisions = 2); 104 void chopAndAppendCubicAtMidTangent(AppendCubicMode, const Sk2f& p0, const Sk2f& p1, 105 const Sk2f& p2, const Sk2f& p3, const Sk2f& tan0, 106 const Sk2f& tan1, int maxFutureSubdivisions); 107 108 void appendMonotonicConic(const Sk2f& p0, const Sk2f& p1, const Sk2f& p2, float w); 109 110 // Transient state used while building a contour. 111 SkPoint fCurrAnchorPoint; 112 PrimitiveTallies fCurrContourTallies; 113 SkCubicType fCurrCubicType; 114 SkDEBUGCODE(bool fBuildingContour = false); 115 116 SkSTArray<128, SkPoint, true> fPoints; 117 SkSTArray<128, Verb, true> fVerbs; 118 SkSTArray<32, float, true> fConicWeights; 119 }; 120 121 inline void GrCCFillGeometry::PrimitiveTallies::operator+=(const PrimitiveTallies& b) { 122 fTriangles += b.fTriangles; 123 fWeightedTriangles += b.fWeightedTriangles; 124 fQuadratics += b.fQuadratics; 125 fCubics += b.fCubics; 126 fConics += b.fConics; 127 } 128 129 GrCCFillGeometry::PrimitiveTallies 130 inline GrCCFillGeometry::PrimitiveTallies::operator-(const PrimitiveTallies& b) const { 131 return {fTriangles - b.fTriangles, 132 fWeightedTriangles - b.fWeightedTriangles, 133 fQuadratics - b.fQuadratics, 134 fCubics - b.fCubics, 135 fConics - b.fConics}; 136 } 137 138 inline bool GrCCFillGeometry::PrimitiveTallies::operator==(const PrimitiveTallies& b) { 139 return fTriangles == b.fTriangles && fWeightedTriangles == b.fWeightedTriangles && 140 fQuadratics == b.fQuadratics && fCubics == b.fCubics && fConics == b.fConics; 141 } 142 143 #endif 144