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1 /* |
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2 * Copyright 2012 Google Inc. |
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3 * |
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4 * Use of this source code is governed by a BSD-style license that can be |
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5 * found in the LICENSE file. |
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6 */ |
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7 #include "SkLineParameters.h" |
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8 #include "SkPathOpsCubic.h" |
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9 #include "SkPathOpsLine.h" |
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10 #include "SkPathOpsQuad.h" |
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11 #include "SkPathOpsRect.h" |
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12 |
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13 const int SkDCubic::gPrecisionUnit = 256; // FIXME: test different values in test framework |
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14 |
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15 // FIXME: cache keep the bounds and/or precision with the caller? |
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16 double SkDCubic::calcPrecision() const { |
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17 SkDRect dRect; |
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18 dRect.setBounds(*this); // OPTIMIZATION: just use setRawBounds ? |
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19 double width = dRect.fRight - dRect.fLeft; |
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20 double height = dRect.fBottom - dRect.fTop; |
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21 return (width > height ? width : height) / gPrecisionUnit; |
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22 } |
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23 |
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24 bool SkDCubic::clockwise() const { |
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25 double sum = (fPts[0].fX - fPts[3].fX) * (fPts[0].fY + fPts[3].fY); |
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26 for (int idx = 0; idx < 3; ++idx) { |
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27 sum += (fPts[idx + 1].fX - fPts[idx].fX) * (fPts[idx + 1].fY + fPts[idx].fY); |
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28 } |
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29 return sum <= 0; |
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30 } |
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31 |
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32 void SkDCubic::Coefficients(const double* src, double* A, double* B, double* C, double* D) { |
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33 *A = src[6]; // d |
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34 *B = src[4] * 3; // 3*c |
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35 *C = src[2] * 3; // 3*b |
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36 *D = src[0]; // a |
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37 *A -= *D - *C + *B; // A = -a + 3*b - 3*c + d |
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38 *B += 3 * *D - 2 * *C; // B = 3*a - 6*b + 3*c |
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39 *C -= 3 * *D; // C = -3*a + 3*b |
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40 } |
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41 |
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42 bool SkDCubic::controlsContainedByEnds() const { |
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43 SkDVector startTan = fPts[1] - fPts[0]; |
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44 if (startTan.fX == 0 && startTan.fY == 0) { |
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45 startTan = fPts[2] - fPts[0]; |
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46 } |
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47 SkDVector endTan = fPts[2] - fPts[3]; |
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48 if (endTan.fX == 0 && endTan.fY == 0) { |
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49 endTan = fPts[1] - fPts[3]; |
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50 } |
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51 if (startTan.dot(endTan) >= 0) { |
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52 return false; |
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53 } |
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54 SkDLine startEdge = {{fPts[0], fPts[0]}}; |
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55 startEdge[1].fX -= startTan.fY; |
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56 startEdge[1].fY += startTan.fX; |
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57 SkDLine endEdge = {{fPts[3], fPts[3]}}; |
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58 endEdge[1].fX -= endTan.fY; |
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59 endEdge[1].fY += endTan.fX; |
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60 double leftStart1 = startEdge.isLeft(fPts[1]); |
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61 if (leftStart1 * startEdge.isLeft(fPts[2]) < 0) { |
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62 return false; |
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63 } |
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64 double leftEnd1 = endEdge.isLeft(fPts[1]); |
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65 if (leftEnd1 * endEdge.isLeft(fPts[2]) < 0) { |
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66 return false; |
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67 } |
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68 return leftStart1 * leftEnd1 >= 0; |
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69 } |
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70 |
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71 bool SkDCubic::endsAreExtremaInXOrY() const { |
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72 return (between(fPts[0].fX, fPts[1].fX, fPts[3].fX) |
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73 && between(fPts[0].fX, fPts[2].fX, fPts[3].fX)) |
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74 || (between(fPts[0].fY, fPts[1].fY, fPts[3].fY) |
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75 && between(fPts[0].fY, fPts[2].fY, fPts[3].fY)); |
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76 } |
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77 |
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78 bool SkDCubic::isLinear(int startIndex, int endIndex) const { |
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79 SkLineParameters lineParameters; |
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80 lineParameters.cubicEndPoints(*this, startIndex, endIndex); |
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81 // FIXME: maybe it's possible to avoid this and compare non-normalized |
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82 lineParameters.normalize(); |
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83 double distance = lineParameters.controlPtDistance(*this, 1); |
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84 if (!approximately_zero(distance)) { |
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85 return false; |
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86 } |
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87 distance = lineParameters.controlPtDistance(*this, 2); |
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88 return approximately_zero(distance); |
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89 } |
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90 |
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91 bool SkDCubic::monotonicInY() const { |
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92 return between(fPts[0].fY, fPts[1].fY, fPts[3].fY) |
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93 && between(fPts[0].fY, fPts[2].fY, fPts[3].fY); |
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94 } |
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95 |
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96 bool SkDCubic::serpentine() const { |
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97 if (!controlsContainedByEnds()) { |
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98 return false; |
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99 } |
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100 double wiggle = (fPts[0].fX - fPts[2].fX) * (fPts[0].fY + fPts[2].fY); |
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101 for (int idx = 0; idx < 2; ++idx) { |
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102 wiggle += (fPts[idx + 1].fX - fPts[idx].fX) * (fPts[idx + 1].fY + fPts[idx].fY); |
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103 } |
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104 double waggle = (fPts[1].fX - fPts[3].fX) * (fPts[1].fY + fPts[3].fY); |
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105 for (int idx = 1; idx < 3; ++idx) { |
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106 waggle += (fPts[idx + 1].fX - fPts[idx].fX) * (fPts[idx + 1].fY + fPts[idx].fY); |
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107 } |
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108 return wiggle * waggle < 0; |
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109 } |
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110 |
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111 // cubic roots |
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112 |
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113 static const double PI = 3.141592653589793; |
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114 |
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115 // from SkGeometry.cpp (and Numeric Solutions, 5.6) |
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116 int SkDCubic::RootsValidT(double A, double B, double C, double D, double t[3]) { |
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117 double s[3]; |
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118 int realRoots = RootsReal(A, B, C, D, s); |
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119 int foundRoots = SkDQuad::AddValidTs(s, realRoots, t); |
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120 return foundRoots; |
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121 } |
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122 |
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123 int SkDCubic::RootsReal(double A, double B, double C, double D, double s[3]) { |
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124 #ifdef SK_DEBUG |
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125 // create a string mathematica understands |
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126 // GDB set print repe 15 # if repeated digits is a bother |
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127 // set print elements 400 # if line doesn't fit |
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128 char str[1024]; |
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129 sk_bzero(str, sizeof(str)); |
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130 SK_SNPRINTF(str, sizeof(str), "Solve[%1.19g x^3 + %1.19g x^2 + %1.19g x + %1.19g == 0, x]", |
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131 A, B, C, D); |
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132 SkPathOpsDebug::MathematicaIze(str, sizeof(str)); |
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133 #if ONE_OFF_DEBUG && ONE_OFF_DEBUG_MATHEMATICA |
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134 SkDebugf("%s\n", str); |
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135 #endif |
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136 #endif |
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137 if (approximately_zero(A) |
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138 && approximately_zero_when_compared_to(A, B) |
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139 && approximately_zero_when_compared_to(A, C) |
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140 && approximately_zero_when_compared_to(A, D)) { // we're just a quadratic |
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141 return SkDQuad::RootsReal(B, C, D, s); |
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142 } |
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143 if (approximately_zero_when_compared_to(D, A) |
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144 && approximately_zero_when_compared_to(D, B) |
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145 && approximately_zero_when_compared_to(D, C)) { // 0 is one root |
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146 int num = SkDQuad::RootsReal(A, B, C, s); |
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147 for (int i = 0; i < num; ++i) { |
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148 if (approximately_zero(s[i])) { |
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149 return num; |
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150 } |
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151 } |
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152 s[num++] = 0; |
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153 return num; |
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154 } |
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155 if (approximately_zero(A + B + C + D)) { // 1 is one root |
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156 int num = SkDQuad::RootsReal(A, A + B, -D, s); |
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157 for (int i = 0; i < num; ++i) { |
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158 if (AlmostDequalUlps(s[i], 1)) { |
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159 return num; |
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160 } |
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161 } |
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162 s[num++] = 1; |
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163 return num; |
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164 } |
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165 double a, b, c; |
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166 { |
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167 double invA = 1 / A; |
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168 a = B * invA; |
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169 b = C * invA; |
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170 c = D * invA; |
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171 } |
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172 double a2 = a * a; |
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173 double Q = (a2 - b * 3) / 9; |
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174 double R = (2 * a2 * a - 9 * a * b + 27 * c) / 54; |
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175 double R2 = R * R; |
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176 double Q3 = Q * Q * Q; |
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177 double R2MinusQ3 = R2 - Q3; |
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178 double adiv3 = a / 3; |
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179 double r; |
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180 double* roots = s; |
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181 if (R2MinusQ3 < 0) { // we have 3 real roots |
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182 double theta = acos(R / sqrt(Q3)); |
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183 double neg2RootQ = -2 * sqrt(Q); |
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184 |
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185 r = neg2RootQ * cos(theta / 3) - adiv3; |
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186 *roots++ = r; |
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187 |
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188 r = neg2RootQ * cos((theta + 2 * PI) / 3) - adiv3; |
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189 if (!AlmostDequalUlps(s[0], r)) { |
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190 *roots++ = r; |
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191 } |
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192 r = neg2RootQ * cos((theta - 2 * PI) / 3) - adiv3; |
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193 if (!AlmostDequalUlps(s[0], r) && (roots - s == 1 || !AlmostDequalUlps(s[1], r))) { |
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194 *roots++ = r; |
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195 } |
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196 } else { // we have 1 real root |
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197 double sqrtR2MinusQ3 = sqrt(R2MinusQ3); |
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198 double A = fabs(R) + sqrtR2MinusQ3; |
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199 A = SkDCubeRoot(A); |
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200 if (R > 0) { |
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201 A = -A; |
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202 } |
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203 if (A != 0) { |
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204 A += Q / A; |
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205 } |
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206 r = A - adiv3; |
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207 *roots++ = r; |
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208 if (AlmostDequalUlps(R2, Q3)) { |
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209 r = -A / 2 - adiv3; |
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210 if (!AlmostDequalUlps(s[0], r)) { |
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211 *roots++ = r; |
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212 } |
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213 } |
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214 } |
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215 return static_cast<int>(roots - s); |
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216 } |
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217 |
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218 // from http://www.cs.sunysb.edu/~qin/courses/geometry/4.pdf |
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219 // c(t) = a(1-t)^3 + 3bt(1-t)^2 + 3c(1-t)t^2 + dt^3 |
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220 // c'(t) = -3a(1-t)^2 + 3b((1-t)^2 - 2t(1-t)) + 3c(2t(1-t) - t^2) + 3dt^2 |
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221 // = 3(b-a)(1-t)^2 + 6(c-b)t(1-t) + 3(d-c)t^2 |
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222 static double derivative_at_t(const double* src, double t) { |
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223 double one_t = 1 - t; |
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224 double a = src[0]; |
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225 double b = src[2]; |
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226 double c = src[4]; |
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227 double d = src[6]; |
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228 return 3 * ((b - a) * one_t * one_t + 2 * (c - b) * t * one_t + (d - c) * t * t); |
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229 } |
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230 |
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231 // OPTIMIZE? compute t^2, t(1-t), and (1-t)^2 and pass them to another version of derivative at t? |
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232 SkDVector SkDCubic::dxdyAtT(double t) const { |
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233 SkDVector result = { derivative_at_t(&fPts[0].fX, t), derivative_at_t(&fPts[0].fY, t) }; |
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234 return result; |
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235 } |
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236 |
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237 // OPTIMIZE? share code with formulate_F1DotF2 |
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238 int SkDCubic::findInflections(double tValues[]) const { |
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239 double Ax = fPts[1].fX - fPts[0].fX; |
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240 double Ay = fPts[1].fY - fPts[0].fY; |
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241 double Bx = fPts[2].fX - 2 * fPts[1].fX + fPts[0].fX; |
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242 double By = fPts[2].fY - 2 * fPts[1].fY + fPts[0].fY; |
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243 double Cx = fPts[3].fX + 3 * (fPts[1].fX - fPts[2].fX) - fPts[0].fX; |
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244 double Cy = fPts[3].fY + 3 * (fPts[1].fY - fPts[2].fY) - fPts[0].fY; |
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245 return SkDQuad::RootsValidT(Bx * Cy - By * Cx, Ax * Cy - Ay * Cx, Ax * By - Ay * Bx, tValues); |
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246 } |
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247 |
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248 static void formulate_F1DotF2(const double src[], double coeff[4]) { |
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249 double a = src[2] - src[0]; |
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250 double b = src[4] - 2 * src[2] + src[0]; |
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251 double c = src[6] + 3 * (src[2] - src[4]) - src[0]; |
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252 coeff[0] = c * c; |
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253 coeff[1] = 3 * b * c; |
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254 coeff[2] = 2 * b * b + c * a; |
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255 coeff[3] = a * b; |
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256 } |
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257 |
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258 /** SkDCubic'(t) = At^2 + Bt + C, where |
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259 A = 3(-a + 3(b - c) + d) |
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260 B = 6(a - 2b + c) |
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261 C = 3(b - a) |
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262 Solve for t, keeping only those that fit between 0 < t < 1 |
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263 */ |
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264 int SkDCubic::FindExtrema(double a, double b, double c, double d, double tValues[2]) { |
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265 // we divide A,B,C by 3 to simplify |
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266 double A = d - a + 3*(b - c); |
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267 double B = 2*(a - b - b + c); |
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268 double C = b - a; |
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269 |
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270 return SkDQuad::RootsValidT(A, B, C, tValues); |
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271 } |
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272 |
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273 /* from SkGeometry.cpp |
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274 Looking for F' dot F'' == 0 |
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275 |
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276 A = b - a |
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277 B = c - 2b + a |
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278 C = d - 3c + 3b - a |
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279 |
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280 F' = 3Ct^2 + 6Bt + 3A |
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281 F'' = 6Ct + 6B |
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282 |
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283 F' dot F'' -> CCt^3 + 3BCt^2 + (2BB + CA)t + AB |
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284 */ |
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285 int SkDCubic::findMaxCurvature(double tValues[]) const { |
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286 double coeffX[4], coeffY[4]; |
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287 int i; |
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288 formulate_F1DotF2(&fPts[0].fX, coeffX); |
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289 formulate_F1DotF2(&fPts[0].fY, coeffY); |
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290 for (i = 0; i < 4; i++) { |
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291 coeffX[i] = coeffX[i] + coeffY[i]; |
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292 } |
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293 return RootsValidT(coeffX[0], coeffX[1], coeffX[2], coeffX[3], tValues); |
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294 } |
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295 |
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296 SkDPoint SkDCubic::top(double startT, double endT) const { |
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297 SkDCubic sub = subDivide(startT, endT); |
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298 SkDPoint topPt = sub[0]; |
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299 if (topPt.fY > sub[3].fY || (topPt.fY == sub[3].fY && topPt.fX > sub[3].fX)) { |
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300 topPt = sub[3]; |
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301 } |
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302 double extremeTs[2]; |
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303 if (!sub.monotonicInY()) { |
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304 int roots = FindExtrema(sub[0].fY, sub[1].fY, sub[2].fY, sub[3].fY, extremeTs); |
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305 for (int index = 0; index < roots; ++index) { |
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306 double t = startT + (endT - startT) * extremeTs[index]; |
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307 SkDPoint mid = ptAtT(t); |
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308 if (topPt.fY > mid.fY || (topPt.fY == mid.fY && topPt.fX > mid.fX)) { |
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309 topPt = mid; |
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310 } |
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311 } |
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312 } |
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313 return topPt; |
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314 } |
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315 |
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316 SkDPoint SkDCubic::ptAtT(double t) const { |
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317 if (0 == t) { |
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318 return fPts[0]; |
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319 } |
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320 if (1 == t) { |
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321 return fPts[3]; |
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322 } |
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323 double one_t = 1 - t; |
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324 double one_t2 = one_t * one_t; |
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325 double a = one_t2 * one_t; |
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326 double b = 3 * one_t2 * t; |
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327 double t2 = t * t; |
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328 double c = 3 * one_t * t2; |
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329 double d = t2 * t; |
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330 SkDPoint result = {a * fPts[0].fX + b * fPts[1].fX + c * fPts[2].fX + d * fPts[3].fX, |
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331 a * fPts[0].fY + b * fPts[1].fY + c * fPts[2].fY + d * fPts[3].fY}; |
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332 return result; |
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333 } |
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334 |
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335 /* |
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336 Given a cubic c, t1, and t2, find a small cubic segment. |
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337 |
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338 The new cubic is defined as points A, B, C, and D, where |
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339 s1 = 1 - t1 |
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340 s2 = 1 - t2 |
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341 A = c[0]*s1*s1*s1 + 3*c[1]*s1*s1*t1 + 3*c[2]*s1*t1*t1 + c[3]*t1*t1*t1 |
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342 D = c[0]*s2*s2*s2 + 3*c[1]*s2*s2*t2 + 3*c[2]*s2*t2*t2 + c[3]*t2*t2*t2 |
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343 |
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344 We don't have B or C. So We define two equations to isolate them. |
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345 First, compute two reference T values 1/3 and 2/3 from t1 to t2: |
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346 |
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347 c(at (2*t1 + t2)/3) == E |
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348 c(at (t1 + 2*t2)/3) == F |
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349 |
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350 Next, compute where those values must be if we know the values of B and C: |
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351 |
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352 _12 = A*2/3 + B*1/3 |
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353 12_ = A*1/3 + B*2/3 |
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354 _23 = B*2/3 + C*1/3 |
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355 23_ = B*1/3 + C*2/3 |
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356 _34 = C*2/3 + D*1/3 |
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357 34_ = C*1/3 + D*2/3 |
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358 _123 = (A*2/3 + B*1/3)*2/3 + (B*2/3 + C*1/3)*1/3 = A*4/9 + B*4/9 + C*1/9 |
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359 123_ = (A*1/3 + B*2/3)*1/3 + (B*1/3 + C*2/3)*2/3 = A*1/9 + B*4/9 + C*4/9 |
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360 _234 = (B*2/3 + C*1/3)*2/3 + (C*2/3 + D*1/3)*1/3 = B*4/9 + C*4/9 + D*1/9 |
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361 234_ = (B*1/3 + C*2/3)*1/3 + (C*1/3 + D*2/3)*2/3 = B*1/9 + C*4/9 + D*4/9 |
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362 _1234 = (A*4/9 + B*4/9 + C*1/9)*2/3 + (B*4/9 + C*4/9 + D*1/9)*1/3 |
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363 = A*8/27 + B*12/27 + C*6/27 + D*1/27 |
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364 = E |
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365 1234_ = (A*1/9 + B*4/9 + C*4/9)*1/3 + (B*1/9 + C*4/9 + D*4/9)*2/3 |
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366 = A*1/27 + B*6/27 + C*12/27 + D*8/27 |
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367 = F |
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368 E*27 = A*8 + B*12 + C*6 + D |
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369 F*27 = A + B*6 + C*12 + D*8 |
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370 |
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371 Group the known values on one side: |
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372 |
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373 M = E*27 - A*8 - D = B*12 + C* 6 |
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374 N = F*27 - A - D*8 = B* 6 + C*12 |
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375 M*2 - N = B*18 |
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376 N*2 - M = C*18 |
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377 B = (M*2 - N)/18 |
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378 C = (N*2 - M)/18 |
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379 */ |
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380 |
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381 static double interp_cubic_coords(const double* src, double t) { |
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382 double ab = SkDInterp(src[0], src[2], t); |
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383 double bc = SkDInterp(src[2], src[4], t); |
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384 double cd = SkDInterp(src[4], src[6], t); |
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385 double abc = SkDInterp(ab, bc, t); |
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386 double bcd = SkDInterp(bc, cd, t); |
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387 double abcd = SkDInterp(abc, bcd, t); |
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388 return abcd; |
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389 } |
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390 |
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391 SkDCubic SkDCubic::subDivide(double t1, double t2) const { |
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392 if (t1 == 0 || t2 == 1) { |
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393 if (t1 == 0 && t2 == 1) { |
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394 return *this; |
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395 } |
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396 SkDCubicPair pair = chopAt(t1 == 0 ? t2 : t1); |
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397 SkDCubic dst = t1 == 0 ? pair.first() : pair.second(); |
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398 return dst; |
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399 } |
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400 SkDCubic dst; |
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401 double ax = dst[0].fX = interp_cubic_coords(&fPts[0].fX, t1); |
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402 double ay = dst[0].fY = interp_cubic_coords(&fPts[0].fY, t1); |
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403 double ex = interp_cubic_coords(&fPts[0].fX, (t1*2+t2)/3); |
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404 double ey = interp_cubic_coords(&fPts[0].fY, (t1*2+t2)/3); |
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405 double fx = interp_cubic_coords(&fPts[0].fX, (t1+t2*2)/3); |
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406 double fy = interp_cubic_coords(&fPts[0].fY, (t1+t2*2)/3); |
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407 double dx = dst[3].fX = interp_cubic_coords(&fPts[0].fX, t2); |
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408 double dy = dst[3].fY = interp_cubic_coords(&fPts[0].fY, t2); |
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409 double mx = ex * 27 - ax * 8 - dx; |
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410 double my = ey * 27 - ay * 8 - dy; |
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411 double nx = fx * 27 - ax - dx * 8; |
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412 double ny = fy * 27 - ay - dy * 8; |
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413 /* bx = */ dst[1].fX = (mx * 2 - nx) / 18; |
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414 /* by = */ dst[1].fY = (my * 2 - ny) / 18; |
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415 /* cx = */ dst[2].fX = (nx * 2 - mx) / 18; |
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416 /* cy = */ dst[2].fY = (ny * 2 - my) / 18; |
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417 // FIXME: call align() ? |
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418 return dst; |
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419 } |
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420 |
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421 void SkDCubic::align(int endIndex, int ctrlIndex, SkDPoint* dstPt) const { |
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422 if (fPts[endIndex].fX == fPts[ctrlIndex].fX) { |
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423 dstPt->fX = fPts[endIndex].fX; |
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424 } |
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425 if (fPts[endIndex].fY == fPts[ctrlIndex].fY) { |
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426 dstPt->fY = fPts[endIndex].fY; |
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427 } |
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428 } |
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429 |
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430 void SkDCubic::subDivide(const SkDPoint& a, const SkDPoint& d, |
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431 double t1, double t2, SkDPoint dst[2]) const { |
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432 SkASSERT(t1 != t2); |
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433 #if 0 |
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434 double ex = interp_cubic_coords(&fPts[0].fX, (t1 * 2 + t2) / 3); |
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435 double ey = interp_cubic_coords(&fPts[0].fY, (t1 * 2 + t2) / 3); |
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436 double fx = interp_cubic_coords(&fPts[0].fX, (t1 + t2 * 2) / 3); |
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437 double fy = interp_cubic_coords(&fPts[0].fY, (t1 + t2 * 2) / 3); |
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438 double mx = ex * 27 - a.fX * 8 - d.fX; |
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439 double my = ey * 27 - a.fY * 8 - d.fY; |
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440 double nx = fx * 27 - a.fX - d.fX * 8; |
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441 double ny = fy * 27 - a.fY - d.fY * 8; |
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442 /* bx = */ dst[0].fX = (mx * 2 - nx) / 18; |
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443 /* by = */ dst[0].fY = (my * 2 - ny) / 18; |
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444 /* cx = */ dst[1].fX = (nx * 2 - mx) / 18; |
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445 /* cy = */ dst[1].fY = (ny * 2 - my) / 18; |
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446 #else |
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447 // this approach assumes that the control points computed directly are accurate enough |
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448 SkDCubic sub = subDivide(t1, t2); |
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449 dst[0] = sub[1] + (a - sub[0]); |
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450 dst[1] = sub[2] + (d - sub[3]); |
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451 #endif |
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452 if (t1 == 0 || t2 == 0) { |
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453 align(0, 1, t1 == 0 ? &dst[0] : &dst[1]); |
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454 } |
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455 if (t1 == 1 || t2 == 1) { |
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456 align(3, 2, t1 == 1 ? &dst[0] : &dst[1]); |
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457 } |
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458 if (precisely_subdivide_equal(dst[0].fX, a.fX)) { |
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459 dst[0].fX = a.fX; |
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460 } |
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461 if (precisely_subdivide_equal(dst[0].fY, a.fY)) { |
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462 dst[0].fY = a.fY; |
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463 } |
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464 if (precisely_subdivide_equal(dst[1].fX, d.fX)) { |
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465 dst[1].fX = d.fX; |
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466 } |
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467 if (precisely_subdivide_equal(dst[1].fY, d.fY)) { |
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468 dst[1].fY = d.fY; |
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469 } |
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470 } |
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471 |
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472 /* classic one t subdivision */ |
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473 static void interp_cubic_coords(const double* src, double* dst, double t) { |
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474 double ab = SkDInterp(src[0], src[2], t); |
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475 double bc = SkDInterp(src[2], src[4], t); |
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476 double cd = SkDInterp(src[4], src[6], t); |
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477 double abc = SkDInterp(ab, bc, t); |
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478 double bcd = SkDInterp(bc, cd, t); |
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479 double abcd = SkDInterp(abc, bcd, t); |
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480 |
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481 dst[0] = src[0]; |
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482 dst[2] = ab; |
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483 dst[4] = abc; |
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484 dst[6] = abcd; |
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485 dst[8] = bcd; |
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486 dst[10] = cd; |
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487 dst[12] = src[6]; |
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488 } |
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489 |
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490 SkDCubicPair SkDCubic::chopAt(double t) const { |
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491 SkDCubicPair dst; |
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492 if (t == 0.5) { |
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493 dst.pts[0] = fPts[0]; |
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494 dst.pts[1].fX = (fPts[0].fX + fPts[1].fX) / 2; |
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495 dst.pts[1].fY = (fPts[0].fY + fPts[1].fY) / 2; |
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496 dst.pts[2].fX = (fPts[0].fX + 2 * fPts[1].fX + fPts[2].fX) / 4; |
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497 dst.pts[2].fY = (fPts[0].fY + 2 * fPts[1].fY + fPts[2].fY) / 4; |
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498 dst.pts[3].fX = (fPts[0].fX + 3 * (fPts[1].fX + fPts[2].fX) + fPts[3].fX) / 8; |
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499 dst.pts[3].fY = (fPts[0].fY + 3 * (fPts[1].fY + fPts[2].fY) + fPts[3].fY) / 8; |
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500 dst.pts[4].fX = (fPts[1].fX + 2 * fPts[2].fX + fPts[3].fX) / 4; |
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501 dst.pts[4].fY = (fPts[1].fY + 2 * fPts[2].fY + fPts[3].fY) / 4; |
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502 dst.pts[5].fX = (fPts[2].fX + fPts[3].fX) / 2; |
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503 dst.pts[5].fY = (fPts[2].fY + fPts[3].fY) / 2; |
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504 dst.pts[6] = fPts[3]; |
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505 return dst; |
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506 } |
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507 interp_cubic_coords(&fPts[0].fX, &dst.pts[0].fX, t); |
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508 interp_cubic_coords(&fPts[0].fY, &dst.pts[0].fY, t); |
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509 return dst; |
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510 } |
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511 |
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512 #ifdef SK_DEBUG |
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513 void SkDCubic::dump() { |
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514 SkDebugf("{{"); |
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515 int index = 0; |
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516 do { |
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517 fPts[index].dump(); |
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518 SkDebugf(", "); |
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519 } while (++index < 3); |
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520 fPts[index].dump(); |
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521 SkDebugf("}}\n"); |
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522 } |
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523 #endif |