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 #ifndef SkPatchUtils_DEFINED 9 #define SkPatchUtils_DEFINED 10 11 #include "SkColorPriv.h" 12 #include "SkMatrix.h" 13 14 class SK_API SkPatchUtils { 15 16 public: 17 /** 18 * Structure that holds the vertex data related to the tessellation of a patch. It is passed 19 * as a parameter to the function getVertexData which sets the points, colors and texture 20 * coordinates of the vertices and the indices for them to be drawn as triangles. 21 */ 22 struct VertexData { 23 int fVertexCount, fIndexCount; 24 SkPoint* fPoints; 25 SkPoint* fTexCoords; 26 uint32_t* fColors; 27 uint16_t* fIndices; 28 VertexDataVertexData29 VertexData() 30 : fVertexCount(0) 31 , fIndexCount(0) 32 , fPoints(nullptr) 33 , fTexCoords(nullptr) 34 , fColors(nullptr) 35 , fIndices(nullptr) { } 36 ~VertexDataVertexData37 ~VertexData() { 38 delete[] fPoints; 39 delete[] fTexCoords; 40 delete[] fColors; 41 delete[] fIndices; 42 } 43 }; 44 45 // Enums for control points based on the order specified in the constructor (clockwise). 46 enum CubicCtrlPts { 47 kTopP0_CubicCtrlPts = 0, 48 kTopP1_CubicCtrlPts = 1, 49 kTopP2_CubicCtrlPts = 2, 50 kTopP3_CubicCtrlPts = 3, 51 52 kRightP0_CubicCtrlPts = 3, 53 kRightP1_CubicCtrlPts = 4, 54 kRightP2_CubicCtrlPts = 5, 55 kRightP3_CubicCtrlPts = 6, 56 57 kBottomP0_CubicCtrlPts = 9, 58 kBottomP1_CubicCtrlPts = 8, 59 kBottomP2_CubicCtrlPts = 7, 60 kBottomP3_CubicCtrlPts = 6, 61 62 kLeftP0_CubicCtrlPts = 0, 63 kLeftP1_CubicCtrlPts = 11, 64 kLeftP2_CubicCtrlPts = 10, 65 kLeftP3_CubicCtrlPts = 9, 66 }; 67 68 // Enum for corner also clockwise. 69 enum Corner { 70 kTopLeft_Corner = 0, 71 kTopRight_Corner, 72 kBottomRight_Corner, 73 kBottomLeft_Corner 74 }; 75 76 enum { 77 kNumCtrlPts = 12, 78 kNumCorners = 4, 79 kNumPtsCubic = 4 80 }; 81 82 /** 83 * Method that calculates a level of detail (number of subdivisions) for a patch in both axis. 84 */ 85 static SkISize GetLevelOfDetail(const SkPoint cubics[12], const SkMatrix* matrix); 86 87 /** 88 * Get the points corresponding to the top cubic of cubics. 89 */ 90 static void getTopCubic(const SkPoint cubics[12], SkPoint points[4]); 91 92 /** 93 * Get the points corresponding to the bottom cubic of cubics. 94 */ 95 static void getBottomCubic(const SkPoint cubics[12], SkPoint points[4]); 96 97 /** 98 * Get the points corresponding to the left cubic of cubics. 99 */ 100 static void getLeftCubic(const SkPoint cubics[12], SkPoint points[4]); 101 102 /** 103 * Get the points corresponding to the right cubic of cubics. 104 */ 105 static void getRightCubic(const SkPoint cubics[12], SkPoint points[4]); 106 107 /** 108 * Function that evaluates the coons patch interpolation. 109 * data refers to the pointer of the PatchData struct in which the tessellation data is set. 110 * cubics refers to the points of the cubics. 111 * lod refers the level of detail for each axis. 112 * colors refers to the corner colors that will be bilerp across the patch (optional parameter) 113 * texCoords refers to the corner texture coordinates that will be bilerp across the patch 114 (optional parameter) 115 */ 116 static bool getVertexData(SkPatchUtils::VertexData* data, const SkPoint cubics[12], 117 const SkColor colors[4], const SkPoint texCoords[4], 118 int lodX, int lodY); 119 }; 120 121 #endif 122