212 lines
7.1 KiB
C#
212 lines
7.1 KiB
C#
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/* The MIT License
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*
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* Copyright (c) 2010 Intel Corporation.
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* All rights reserved.
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*
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* Based on the convexdecomposition library from
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* <http://codesuppository.googlecode.com> by John W. Ratcliff and Stan Melax.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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namespace OpenSim.Region.Physics.ConvexDecompositionDotNet
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{
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public enum PlaneTriResult : int
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{
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PTR_FRONT,
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PTR_BACK,
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PTR_SPLIT
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}
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public static class PlaneTri
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{
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private static float DistToPt(float3 p, float4 plane)
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{
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return p.x * plane.x + p.y * plane.y + p.z * plane.z + plane.w;
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}
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private static PlaneTriResult getSidePlane(float3 p, float4 plane, float epsilon)
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{
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float d = DistToPt(p, plane);
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if ((d + epsilon) > 0f)
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return PlaneTriResult.PTR_FRONT; // it is 'in front' within the provided epsilon value.
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return PlaneTriResult.PTR_BACK;
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}
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private static void add(float3 p, float3[] dest, ref int pcount)
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{
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dest[pcount++] = new float3(p);
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Debug.Assert(pcount <= 4);
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}
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// assumes that the points are on opposite sides of the plane!
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private static void intersect(float3 p1, float3 p2, float3 split, float4 plane)
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{
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float dp1 = DistToPt(p1, plane);
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float[] dir = new float[3];
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dir[0] = p2[0] - p1[0];
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dir[1] = p2[1] - p1[1];
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dir[2] = p2[2] - p1[2];
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float dot1 = dir[0] * plane[0] + dir[1] * plane[1] + dir[2] * plane[2];
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float dot2 = dp1 - plane[3];
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float t = -(plane[3] + dot2) / dot1;
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split.x = (dir[0] * t) + p1[0];
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split.y = (dir[1] * t) + p1[1];
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split.z = (dir[2] * t) + p1[2];
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}
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public static PlaneTriResult planeTriIntersection(float4 plane, FaceTri triangle, float epsilon, ref float3[] front, out int fcount, ref float3[] back, out int bcount)
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{
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fcount = 0;
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bcount = 0;
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// get the three vertices of the triangle.
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float3 p1 = triangle.P1;
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float3 p2 = triangle.P2;
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float3 p3 = triangle.P3;
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PlaneTriResult r1 = getSidePlane(p1, plane, epsilon); // compute the side of the plane each vertex is on
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PlaneTriResult r2 = getSidePlane(p2, plane, epsilon);
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PlaneTriResult r3 = getSidePlane(p3, plane, epsilon);
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if (r1 == r2 && r1 == r3) // if all three vertices are on the same side of the plane.
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{
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if (r1 == PlaneTriResult.PTR_FRONT) // if all three are in front of the plane, then copy to the 'front' output triangle.
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{
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add(p1, front, ref fcount);
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add(p2, front, ref fcount);
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add(p3, front, ref fcount);
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}
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else
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{
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add(p1, back, ref bcount); // if all three are in 'back' then copy to the 'back' output triangle.
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add(p2, back, ref bcount);
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add(p3, back, ref bcount);
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}
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return r1; // if all three points are on the same side of the plane return result
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}
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// ok.. we need to split the triangle at the plane.
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// First test ray segment P1 to P2
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if (r1 == r2) // if these are both on the same side...
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{
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if (r1 == PlaneTriResult.PTR_FRONT)
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{
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add(p1, front, ref fcount);
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add(p2, front, ref fcount);
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}
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else
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{
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add(p1, back, ref bcount);
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add(p2, back, ref bcount);
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}
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}
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else
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{
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float3 split = new float3();
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intersect(p1, p2, split, plane);
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if (r1 == PlaneTriResult.PTR_FRONT)
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{
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add(p1, front, ref fcount);
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add(split, front, ref fcount);
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add(split, back, ref bcount);
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add(p2, back, ref bcount);
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}
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else
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{
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add(p1, back, ref bcount);
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add(split, back, ref bcount);
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add(split, front, ref fcount);
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add(p2, front, ref fcount);
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}
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}
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// Next test ray segment P2 to P3
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if (r2 == r3) // if these are both on the same side...
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{
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if (r3 == PlaneTriResult.PTR_FRONT)
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{
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add(p3, front, ref fcount);
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}
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else
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{
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add(p3, back, ref bcount);
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}
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}
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else
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{
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float3 split = new float3(); // split the point
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intersect(p2, p3, split, plane);
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if (r3 == PlaneTriResult.PTR_FRONT)
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{
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add(split, front, ref fcount);
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add(split, back, ref bcount);
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add(p3, front, ref fcount);
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}
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else
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{
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add(split, front, ref fcount);
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add(split, back, ref bcount);
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add(p3, back, ref bcount);
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}
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}
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// Next test ray segment P3 to P1
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if (r3 != r1) // if these are both on the same side...
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{
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float3 split = new float3(); // split the point
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intersect(p3, p1, split, plane);
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if (r1 == PlaneTriResult.PTR_FRONT)
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{
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add(split, front, ref fcount);
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add(split, back, ref bcount);
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}
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else
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{
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add(split, front, ref fcount);
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add(split, back, ref bcount);
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}
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}
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return PlaneTriResult.PTR_SPLIT;
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}
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}
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}
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