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1/* The MIT License
2 *
3 * Copyright (c) 2010 Intel Corporation.
4 * All rights reserved.
5 *
6 * Based on the convexdecomposition library from
7 * <http://codesuppository.googlecode.com> by John W. Ratcliff and Stan Melax.
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a copy
10 * of this software and associated documentation files (the "Software"), to deal
11 * in the Software without restriction, including without limitation the rights
12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the Software is
14 * furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included in
17 * all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 * THE SOFTWARE.
26 */
27
28using System;
29using System.Collections.Generic;
30using System.Diagnostics;
31
32namespace OpenSim.Region.Physics.ConvexDecompositionDotNet
33{
34 public enum PlaneTriResult : int
35 {
36 PTR_FRONT,
37 PTR_BACK,
38 PTR_SPLIT
39 }
40
41 public static class PlaneTri
42 {
43 private static float DistToPt(float3 p, float4 plane)
44 {
45 return p.x * plane.x + p.y * plane.y + p.z * plane.z + plane.w;
46 }
47
48 private static PlaneTriResult getSidePlane(float3 p, float4 plane, float epsilon)
49 {
50 float d = DistToPt(p, plane);
51
52 if ((d + epsilon) > 0f)
53 return PlaneTriResult.PTR_FRONT; // it is 'in front' within the provided epsilon value.
54
55 return PlaneTriResult.PTR_BACK;
56 }
57
58 private static void add(float3 p, float3[] dest, ref int pcount)
59 {
60 dest[pcount++] = new float3(p);
61 Debug.Assert(pcount <= 4);
62 }
63
64 // assumes that the points are on opposite sides of the plane!
65 private static void intersect(float3 p1, float3 p2, float3 split, float4 plane)
66 {
67 float dp1 = DistToPt(p1, plane);
68 float[] dir = new float[3];
69
70 dir[0] = p2[0] - p1[0];
71 dir[1] = p2[1] - p1[1];
72 dir[2] = p2[2] - p1[2];
73
74 float dot1 = dir[0] * plane[0] + dir[1] * plane[1] + dir[2] * plane[2];
75 float dot2 = dp1 - plane[3];
76
77 float t = -(plane[3] + dot2) / dot1;
78
79 split.x = (dir[0] * t) + p1[0];
80 split.y = (dir[1] * t) + p1[1];
81 split.z = (dir[2] * t) + p1[2];
82 }
83
84 public static PlaneTriResult planeTriIntersection(float4 plane, FaceTri triangle, float epsilon, ref float3[] front, out int fcount, ref float3[] back, out int bcount)
85 {
86 fcount = 0;
87 bcount = 0;
88
89 // get the three vertices of the triangle.
90 float3 p1 = triangle.P1;
91 float3 p2 = triangle.P2;
92 float3 p3 = triangle.P3;
93
94 PlaneTriResult r1 = getSidePlane(p1, plane, epsilon); // compute the side of the plane each vertex is on
95 PlaneTriResult r2 = getSidePlane(p2, plane, epsilon);
96 PlaneTriResult r3 = getSidePlane(p3, plane, epsilon);
97
98 if (r1 == r2 && r1 == r3) // if all three vertices are on the same side of the plane.
99 {
100 if (r1 == PlaneTriResult.PTR_FRONT) // if all three are in front of the plane, then copy to the 'front' output triangle.
101 {
102 add(p1, front, ref fcount);
103 add(p2, front, ref fcount);
104 add(p3, front, ref fcount);
105 }
106 else
107 {
108 add(p1, back, ref bcount); // if all three are in 'back' then copy to the 'back' output triangle.
109 add(p2, back, ref bcount);
110 add(p3, back, ref bcount);
111 }
112 return r1; // if all three points are on the same side of the plane return result
113 }
114
115 // ok.. we need to split the triangle at the plane.
116
117 // First test ray segment P1 to P2
118 if (r1 == r2) // if these are both on the same side...
119 {
120 if (r1 == PlaneTriResult.PTR_FRONT)
121 {
122 add(p1, front, ref fcount);
123 add(p2, front, ref fcount);
124 }
125 else
126 {
127 add(p1, back, ref bcount);
128 add(p2, back, ref bcount);
129 }
130 }
131 else
132 {
133 float3 split = new float3();
134 intersect(p1, p2, split, plane);
135
136 if (r1 == PlaneTriResult.PTR_FRONT)
137 {
138
139 add(p1, front, ref fcount);
140 add(split, front, ref fcount);
141
142 add(split, back, ref bcount);
143 add(p2, back, ref bcount);
144
145 }
146 else
147 {
148 add(p1, back, ref bcount);
149 add(split, back, ref bcount);
150
151 add(split, front, ref fcount);
152 add(p2, front, ref fcount);
153 }
154
155 }
156
157 // Next test ray segment P2 to P3
158 if (r2 == r3) // if these are both on the same side...
159 {
160 if (r3 == PlaneTriResult.PTR_FRONT)
161 {
162 add(p3, front, ref fcount);
163 }
164 else
165 {
166 add(p3, back, ref bcount);
167 }
168 }
169 else
170 {
171 float3 split = new float3(); // split the point
172 intersect(p2, p3, split, plane);
173
174 if (r3 == PlaneTriResult.PTR_FRONT)
175 {
176 add(split, front, ref fcount);
177 add(split, back, ref bcount);
178
179 add(p3, front, ref fcount);
180 }
181 else
182 {
183 add(split, front, ref fcount);
184 add(split, back, ref bcount);
185
186 add(p3, back, ref bcount);
187 }
188 }
189
190 // Next test ray segment P3 to P1
191 if (r3 != r1) // if these are both on the same side...
192 {
193 float3 split = new float3(); // split the point
194 intersect(p3, p1, split, plane);
195
196 if (r1 == PlaneTriResult.PTR_FRONT)
197 {
198 add(split, front, ref fcount);
199 add(split, back, ref bcount);
200 }
201 else
202 {
203 add(split, front, ref fcount);
204 add(split, back, ref bcount);
205 }
206 }
207
208 return PlaneTriResult.PTR_SPLIT;
209 }
210 }
211}