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592
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1 /**
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2 * Stone of Orthanc
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3 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
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4 * Department, University Hospital of Liege, Belgium
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5 * Copyright (C) 2017-2019 Osimis S.A., Belgium
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6 *
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7 * This program is free software: you can redistribute it and/or
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8 * modify it under the terms of the GNU Affero General Public License
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9 * as published by the Free Software Foundation, either version 3 of
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10 * the License, or (at your option) any later version.
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11 *
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12 * This program is distributed in the hope that it will be useful, but
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13 * WITHOUT ANY WARRANTY; without even the implied warranty of
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14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 * Affero General Public License for more details.
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16 *
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17 * You should have received a copy of the GNU Affero General Public License
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18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
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19 **/
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20
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21
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22 #include "OpenGLLinesProgram.h"
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23
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24 #include <Core/OrthancException.h>
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25
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26
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27 static const unsigned int COMPONENTS_POSITION = 3;
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28 static const unsigned int COMPONENTS_MITER = 2;
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29
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30
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31 static const char* VERTEX_SHADER =
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32 "attribute vec2 a_miter_direction; \n"
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33 "attribute vec4 a_position; \n"
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34 "uniform float u_thickness; \n"
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35 "uniform mat4 u_matrix; \n"
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36 "varying float v_distance; \n"
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37 "void main() \n"
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38 "{ \n"
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39 " v_distance = a_position.z; \n"
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40 " gl_Position = u_matrix * vec4(a_position.xy + a_position.z * a_miter_direction * u_thickness, 0, 1); \n"
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41 "}";
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42
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43
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44 static const char* FRAGMENT_SHADER =
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45 "uniform bool u_antialiasing; \n"
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46 "uniform float u_antialiasing_start; \n"
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47 "uniform vec3 u_color; \n"
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48 "varying float v_distance; \n" // Distance of the point to the segment
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49 "void main() \n"
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50 "{ \n"
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51 " float d = abs(v_distance); \n"
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52 " if (!u_antialiasing || \n"
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53 " d <= u_antialiasing_start) \n"
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54 " gl_FragColor = vec4(u_color, 1); \n"
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55 " else if (d >= 1.0) \n"
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56 " gl_FragColor = vec4(0, 0, 0, 0); \n"
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57 " else \n"
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58 " { \n"
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59 " float alpha = 1.0 - smoothstep(u_antialiasing_start, 1.0, d); \n"
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60 " gl_FragColor = vec4(u_color * alpha, alpha); \n"
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61 " } \n"
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62 "}";
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63
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64
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65 namespace OrthancStone
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66 {
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67 namespace Internals
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68 {
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69 class OpenGLLinesProgram::Data::Segment
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70 {
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71 private:
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72 bool isEmpty_;
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73 double x1_;
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74 double y1_;
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75 double x2_;
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76 double y2_;
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77 double miterX1_;
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78 double miterY1_;
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79 double miterX2_;
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80 double miterY2_;
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81
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82 Vector lineAbove_; // In homogeneous coordinates (size = 3)
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83 Vector lineBelow_;
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84
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85 public:
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86 Segment(const PolylineSceneLayer::Chain& chain,
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87 size_t index1,
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88 size_t index2) :
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89 isEmpty_(false)
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90 {
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91 if (index1 >= chain.size() ||
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92 index2 >= chain.size())
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93 {
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94 throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
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95 }
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96 else
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97 {
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98 const ScenePoint2D& p = chain[index1];
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99 const ScenePoint2D& q = chain[index2];
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100
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101 x1_ = p.GetX();
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102 y1_ = p.GetY();
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103 x2_ = q.GetX();
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104 y2_ = q.GetY();
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105
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106 const double dx = x2_ - x1_;
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107 const double dy = y2_ - y1_;
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108 const double norm = sqrt(dx * dx + dy * dy);
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109
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110 if (LinearAlgebra::IsCloseToZero(norm))
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111 {
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112 isEmpty_ = true;
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113 }
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114 else
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115 {
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116 isEmpty_ = false;
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117 const double normalX = -dy / norm;
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118 const double normalY = dx / norm;
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119
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120 miterX1_ = normalX;
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121 miterY1_ = normalY;
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122 miterX2_ = normalX;
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123 miterY2_ = normalY;
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124
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125 Vector a = LinearAlgebra::CreateVector(x1_ + normalX, y1_ + normalY, 1);
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126 Vector b = LinearAlgebra::CreateVector(x2_ + normalX, y2_ + normalY, 1);
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127 LinearAlgebra::CrossProduct(lineAbove_, a, b);
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128
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129 a = LinearAlgebra::CreateVector(x1_ - normalX, y1_ - normalY, 1);
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130 b = LinearAlgebra::CreateVector(x2_ - normalX, y2_ - normalY, 1);
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131 LinearAlgebra::CrossProduct(lineBelow_, a, b);
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132 }
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133 }
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134 }
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135
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136 bool IsEmpty() const
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137 {
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138 return isEmpty_;
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139 }
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140
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141 static double ComputeSignedArea(double x1,
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142 double y1,
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143 double x2,
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144 double y2,
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145 double x3,
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146 double y3)
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147 {
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148 // This computes the signed area of a 2D triangle. This
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149 // formula is e.g. used in the sorting algorithm of Graham's
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150 // scan to compute the convex hull.
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151 // https://en.wikipedia.org/wiki/Graham_scan
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152 return (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1);
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153 }
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154
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155 static void CreateMiter(Segment& left,
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156 Segment& right)
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157 {
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158 if (!left.IsEmpty() &&
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159 !right.IsEmpty())
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160 {
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161 Vector above, below;
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162 LinearAlgebra::CrossProduct(above, left.lineAbove_, right.lineAbove_);
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163 LinearAlgebra::CrossProduct(below, left.lineBelow_, right.lineBelow_);
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164
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165 if (!LinearAlgebra::IsCloseToZero(above[2]) &&
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166 !LinearAlgebra::IsCloseToZero(below[2]))
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167 {
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168 // Back to inhomogeneous 2D coordinates
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169 above /= above[2];
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170 below /= below[2];
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171
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172 // Check whether "above" and "below" intersection points
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173 // are on the half-plane defined by the endpoints of the
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174 // two segments. This is an indicator of whether the angle
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175 // is too acute.
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176 double s1 = ComputeSignedArea(left.x1_, left.y1_,
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177 above[0], above[1],
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178 right.x2_, right.y2_);
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179 double s2 = ComputeSignedArea(left.x1_, left.y1_,
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180 below[0], below[1],
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181 right.x2_, right.y2_);
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182
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183 // The two signed areas must have the same sign
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184 if (s1 * s2 >= 0)
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185 {
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186 left.miterX2_ = above[0] - left.x2_;
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187 left.miterY2_ = above[1] - left.y2_;
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188
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189 right.miterX1_ = left.miterX2_;
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190 right.miterY1_ = left.miterY2_;
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191 }
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192 }
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193 }
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194 }
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195
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196 void AddTriangles(std::vector<float>& coords,
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197 std::vector<float>& miterDirections)
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198 {
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199 if (isEmpty_)
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200 {
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201 throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
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202 }
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203
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204 // First triangle
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205 coords.push_back(x1_);
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206 coords.push_back(y1_);
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207 coords.push_back(1);
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208 coords.push_back(x2_);
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209 coords.push_back(y2_);
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210 coords.push_back(-1);
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211 coords.push_back(x2_);
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212 coords.push_back(y2_);
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213 coords.push_back(1);
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214
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215 miterDirections.push_back(miterX1_);
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216 miterDirections.push_back(miterY1_);
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217 miterDirections.push_back(miterX2_);
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218 miterDirections.push_back(miterY2_);
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219 miterDirections.push_back(miterX2_);
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220 miterDirections.push_back(miterY2_);
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221
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222 // Second triangle
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223 coords.push_back(x1_);
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224 coords.push_back(y1_);
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225 coords.push_back(1);
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226 coords.push_back(x1_);
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227 coords.push_back(y1_);
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228 coords.push_back(-1);
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229 coords.push_back(x2_);
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230 coords.push_back(y2_);
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231 coords.push_back(-1);
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232
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233 miterDirections.push_back(miterX1_);
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234 miterDirections.push_back(miterY1_);
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235 miterDirections.push_back(miterX1_);
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236 miterDirections.push_back(miterY1_);
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237 miterDirections.push_back(miterX2_);
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238 miterDirections.push_back(miterY2_);
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239 }
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240 };
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241
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242
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243 OpenGLLinesProgram::Data::Data(OpenGL::IOpenGLContext& context,
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244 const PolylineSceneLayer& layer) :
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245 context_(context),
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246 verticesCount_(0),
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247 thickness_(layer.GetThickness()),
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248 red_(layer.GetRedAsFloat()),
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249 green_(layer.GetGreenAsFloat()),
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250 blue_(layer.GetBlueAsFloat())
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251 {
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252 // High-level reference:
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253 // https://mattdesl.svbtle.com/drawing-lines-is-hard
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254 // https://forum.libcinder.org/topic/smooth-thick-lines-using-geometry-shader
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255
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256 size_t countVertices = 0;
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257 for (size_t i = 0; i < layer.GetChainsCount(); i++)
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258 {
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259 size_t countSegments = layer.GetChain(i).size() - 1;
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260
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261 if (layer.IsClosedChain(i))
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262 {
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263 countSegments++;
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264 }
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265
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266 // Each segment is made of 2 triangles. One triangle is
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267 // defined by 3 points in 2D => 6 vertices per segment.
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268 countVertices += countSegments * 2 * 3;
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269 }
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270
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271 std::vector<float> coords, miterDirections;
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272 coords.reserve(countVertices * COMPONENTS_POSITION);
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273 miterDirections.reserve(countVertices * COMPONENTS_MITER);
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274
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275 for (size_t i = 0; i < layer.GetChainsCount(); i++)
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276 {
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277 const PolylineSceneLayer::Chain& chain = layer.GetChain(i);
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278
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279 if (chain.size() > 1)
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280 {
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281 std::vector<Segment> segments;
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282 for (size_t j = 1; j < chain.size(); j++)
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283 {
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284 segments.push_back(Segment(chain, j - 1, j));
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285 }
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286
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287 if (layer.IsClosedChain(i))
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288 {
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289 segments.push_back(Segment(chain, chain.size() - 1, 0));
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290 }
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291
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292 // Try and create nice miters
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293 for (size_t j = 1; j < segments.size(); j++)
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294 {
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295 Segment::CreateMiter(segments[j - 1], segments[j]);
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296 }
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297
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298 if (layer.IsClosedChain(i))
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299 {
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300 Segment::CreateMiter(segments.back(), segments.front());
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301 }
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302
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303 for (size_t j = 0; j < segments.size(); j++)
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304 {
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305 if (!segments[j].IsEmpty())
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306 {
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307 segments[j].AddTriangles(coords, miterDirections);
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308 }
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309 }
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310 }
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311 }
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312
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313 if (!coords.empty())
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314 {
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315 verticesCount_ = coords.size() / COMPONENTS_POSITION;
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316
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317 context_.MakeCurrent();
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318 glGenBuffers(2, buffers_);
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319
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320 glBindBuffer(GL_ARRAY_BUFFER, buffers_[0]);
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321 glBufferData(GL_ARRAY_BUFFER, sizeof(float) * coords.size(), &coords[0], GL_STATIC_DRAW);
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322
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323 glBindBuffer(GL_ARRAY_BUFFER, buffers_[1]);
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324 glBufferData(GL_ARRAY_BUFFER, sizeof(float) * miterDirections.size(), &miterDirections[0], GL_STATIC_DRAW);
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325 }
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326 }
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327
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328
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329 OpenGLLinesProgram::Data::~Data()
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330 {
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331 if (!IsEmpty())
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332 {
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333 context_.MakeCurrent();
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334 glDeleteBuffers(2, buffers_);
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335 }
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336 }
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337
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338
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339 GLuint OpenGLLinesProgram::Data::GetVerticesBuffer() const
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340 {
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341 if (IsEmpty())
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342 {
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343 throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
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344 }
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345 else
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346 {
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347 return buffers_[0];
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348 }
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349 }
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350
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351
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352 GLuint OpenGLLinesProgram::Data::GetMiterDirectionsBuffer() const
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353 {
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354 if (IsEmpty())
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355 {
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356 throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
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357 }
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358 else
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359 {
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360 return buffers_[1];
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361 }
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362 }
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363
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364
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365 OpenGLLinesProgram::OpenGLLinesProgram(OpenGL::IOpenGLContext& context) :
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366 context_(context)
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367 {
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368
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369 context_.MakeCurrent();
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370
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371 program_.reset(new OpenGL::OpenGLProgram);
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372 program_->CompileShaders(VERTEX_SHADER, FRAGMENT_SHADER);
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373 }
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374
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375
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376 void OpenGLLinesProgram::Apply(const Data& data,
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377 const AffineTransform2D& transform,
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378 bool antialiasing,
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379 bool scaleIndependantThickness)
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380 {
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381 if (!data.IsEmpty())
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382 {
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383 context_.MakeCurrent();
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384 program_->Use();
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385
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386 GLint locationPosition = program_->GetAttributeLocation("a_position");
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387 GLint locationMiterDirection = program_->GetAttributeLocation("a_miter_direction");
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388
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389 float m[16];
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390 transform.ConvertToOpenGLMatrix(m, context_.GetCanvasWidth(), context_.GetCanvasHeight());
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391
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392 glUniformMatrix4fv(program_->GetUniformLocation("u_matrix"), 1, GL_FALSE, m);
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393 glUniform3f(program_->GetUniformLocation("u_color"),
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394 data.GetRed(), data.GetGreen(), data.GetBlue());
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395
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396 glBindBuffer(GL_ARRAY_BUFFER, data.GetVerticesBuffer());
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397 glEnableVertexAttribArray(locationPosition);
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398 glVertexAttribPointer(locationPosition, COMPONENTS_POSITION, GL_FLOAT, GL_FALSE, 0, 0);
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399
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400 glBindBuffer(GL_ARRAY_BUFFER, data.GetMiterDirectionsBuffer());
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401 glEnableVertexAttribArray(locationMiterDirection);
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402 glVertexAttribPointer(locationMiterDirection, COMPONENTS_MITER, GL_FLOAT, GL_FALSE, 0, 0);
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403
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404 glUniform1i(program_->GetUniformLocation("u_antialiasing"), (antialiasing ? 1 : 0));
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405
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406 const double zoom = transform.ComputeZoom();
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407 const double thickness = data.GetThickness() / 2.0;
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408 const double aliasingBorder = 2.0; // Border for antialiasing ramp, in pixels
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409 assert(aliasingBorder > 0); // Prevent division by zero with "t1"
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410
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411 if (scaleIndependantThickness)
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412 {
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413 if (antialiasing)
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414 {
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415 double t1 = std::max(thickness, aliasingBorder);
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416 double t0 = std::max(0.0, thickness - aliasingBorder);
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417
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418 glUniform1f(program_->GetUniformLocation("u_thickness"), t1 / zoom);
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419 glUniform1f(program_->GetUniformLocation("u_antialiasing_start"), t0 / t1);
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420 }
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421 else
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422 {
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423 glUniform1f(program_->GetUniformLocation("u_thickness"), thickness / zoom);
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424 }
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425 }
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426 else
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427 {
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428 if (antialiasing)
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429 {
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430 double t1 = std::max(thickness, aliasingBorder / zoom);
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431 double t0 = std::max(0.0, thickness - aliasingBorder / zoom);
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432
|
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433 glUniform1f(program_->GetUniformLocation("u_thickness"), t1);
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434 glUniform1f(program_->GetUniformLocation("u_antialiasing_start"), t0 / t1);
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435 }
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436 else
|
|
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437 {
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438 glUniform1f(program_->GetUniformLocation("u_thickness"), thickness);
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|
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439 }
|
|
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440 }
|
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441
|
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442 if (antialiasing)
|
|
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443 {
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444 glEnable(GL_BLEND);
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445 glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
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446 glDrawArrays(GL_TRIANGLES, 0, data.GetVerticesCount());
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447 glDisable(GL_BLEND);
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448 }
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449 else
|
|
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450 {
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451 glDrawArrays(GL_TRIANGLES, 0, data.GetVerticesCount());
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|
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452 }
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|
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453
|
|
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454 glDisableVertexAttribArray(locationPosition);
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|
|
455 glDisableVertexAttribArray(locationMiterDirection);
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|
|
456 }
|
|
|
457 }
|
|
|
458 }
|
|
|
459 }
|
