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