1 /* 2 Copyright (c) 2013-2017 Timur Gafarov 3 4 Boost Software License - Version 1.0 - August 17th, 2003 5 6 Permission is hereby granted, free of charge, to any person or organization 7 obtaining a copy of the software and accompanying documentation covered by 8 this license (the "Software") to use, reproduce, display, distribute, 9 execute, and transmit the Software, and to prepare derivative works of the 10 Software, and to permit third-parties to whom the Software is furnished to 11 do so, all subject to the following: 12 13 The copyright notices in the Software and this entire statement, including 14 the above license grant, this restriction and the following disclaimer, 15 must be included in all copies of the Software, in whole or in part, and 16 all derivative works of the Software, unless such copies or derivative 17 works are solely in the form of machine-executable object code generated by 18 a source language processor. 19 20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT 23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE 24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, 25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 26 DEALINGS IN THE SOFTWARE. 27 */ 28 29 module dmech.clipping; 30 31 import dlib.math.vector; 32 33 /* 34 * 2D feature clipping. 35 * Feature is a quad, triangle, line segment or point 36 */ 37 38 struct Feature 39 { 40 Vector2f[4] vertices; 41 uint numVertices = 0; 42 } 43 44 bool pointInPolygon(Vector2f[] vert, uint len, Vector2f point) 45 { 46 int i, j = 0; 47 bool c = false; 48 for (i = 0, j = len - 1; i < len; j = i++) 49 { 50 if ( ((vert[i].y > point.y) != (vert[j].y > point.y)) && 51 (point.x < (vert[j].x - vert[i].x) * (point.y - vert[i].y) / (vert[j].y - vert[i].y) + vert[i].x) ) 52 c = !c; 53 } 54 return c; 55 } 56 57 void featurePointsIn(Feature f1, Feature f2, ref bool[4] res) 58 { 59 for (uint i = 0; i < f1.numVertices; i++) 60 res[i] = pointInPolygon(f2.vertices, f2.numVertices, f1.vertices[i]); 61 } 62 63 bool allIsTrue(ref bool[4] arr, uint len) 64 { 65 for (uint i = 0; i < len; i++) 66 if (!arr[i]) 67 return false; 68 return true; 69 } 70 71 // Detect intersection of two line segments 72 bool segmentIsec( 73 Vector2f start1, Vector2f end1, 74 Vector2f start2, Vector2f end2, 75 out Vector2f out_intersection) 76 { 77 Vector2f dir1 = end1 - start1; 78 Vector2f dir2 = end2 - start2; 79 80 float a1 = -dir1.y; 81 float b1 = +dir1.x; 82 float d1 = -(a1*start1.x + b1*start1.y); 83 84 float a2 = -dir2.y; 85 float b2 = +dir2.x; 86 float d2 = -(a2*start2.x + b2*start2.y); 87 88 float seg1_line2_start = a2*start1.x + b2*start1.y + d2; 89 float seg1_line2_end = a2*end1.x + b2*end1.y + d2; 90 91 float seg2_line1_start = a1*start2.x + b1*start2.y + d1; 92 float seg2_line1_end = a1*end2.x + b1*end2.y + d1; 93 94 if (seg1_line2_start * seg1_line2_end >= 0 || 95 seg2_line1_start * seg2_line1_end >= 0) 96 return false; 97 98 float u = seg1_line2_start / (seg1_line2_start - seg1_line2_end); 99 out_intersection = start1 + dir1 * u; 100 101 return true; 102 } 103 104 T distancesqr2(T) (Vector!(T,2) a, Vector!(T,2) b) 105 body 106 { 107 T dx = a.x - b.x; 108 T dy = a.y - b.y; 109 return ((dx * dx) + (dy * dy)); 110 } 111 112 // Perform clipping of two features 113 bool clip( 114 Feature f1, 115 Feature f2, 116 out Vector2f[8] outPts, 117 out uint numOutPts) 118 { 119 /* 120 if (f1.numVertices == 1) 121 { 122 outPts[0] = f1.vertices[0]; 123 numOutPts = 1; 124 } 125 if (f2.numVertices == 1) 126 { 127 outPts[0] = f2.vertices[0]; 128 numOutPts = 1; 129 } 130 */ 131 132 // Check if features are almost the same 133 if (f1.numVertices == f2.numVertices) 134 { 135 bool same = false; 136 for (uint i = 0; i < f1.numVertices; i++) 137 same = same || distancesqr2(f1.vertices[i], f2.vertices[i]) < 0.001f; 138 if (same) 139 { 140 // result is f1 141 for (uint i = 0; i < f1.numVertices; i++) 142 outPts[i] = f1.vertices[i]; 143 numOutPts = f1.numVertices; 144 return true; 145 } 146 } 147 148 // Check if one feature fully encloses another 149 bool[4] r1; 150 bool[4] r2; 151 152 if (f2.numVertices > 2) 153 featurePointsIn(f1, f2, r1); 154 if (f1.numVertices > 2) 155 featurePointsIn(f2, f1, r2); 156 157 if (allIsTrue(r1, f1.numVertices)) 158 { 159 // f2 fully encloses f1, result is f1 160 for (uint i = 0; i < f1.numVertices; i++) 161 outPts[i] = f1.vertices[i]; 162 numOutPts = f1.numVertices; 163 return true; 164 } 165 166 if (allIsTrue(r2, f2.numVertices)) 167 { 168 // f1 fully encloses f2, result is f2 169 for (uint i = 0; i < f2.numVertices; i++) 170 outPts[i] = f2.vertices[i]; 171 numOutPts = f2.numVertices; 172 return true; 173 } 174 175 // Add enclosed points to result 176 numOutPts = 0; 177 foreach(i, r; r1) 178 if (r) 179 { 180 outPts[numOutPts] = f1.vertices[i]; 181 numOutPts++; 182 } 183 foreach(i, r; r2) 184 if (r) 185 { 186 outPts[numOutPts] = f2.vertices[i]; 187 numOutPts++; 188 } 189 190 // Check one feature's edges against another's 191 // TODO: check only those edges that belong to enclosed points 192 for (uint i = 0; i < f1.numVertices; i++) 193 for (uint j = 0; j < f2.numVertices; j++) 194 { 195 uint i2 = i + 1; 196 if (i2 == f1.numVertices) i2 = 0; 197 uint j2 = j + 1; 198 if (j2 == f2.numVertices) j2 = 0; 199 200 Vector2f a = f1.vertices[i]; 201 Vector2f b = f1.vertices[i2]; 202 Vector2f c = f2.vertices[j]; 203 Vector2f d = f2.vertices[j2]; 204 205 Vector2f ip; 206 if (segmentIsec(a, b, c, d, ip)) 207 { 208 if (numOutPts < 8) 209 { 210 outPts[numOutPts] = ip; 211 numOutPts++; 212 } 213 } 214 } 215 216 return (numOutPts > 0); 217 } 218