/*
* Java port of Bullet (c) 2008 Martin Dvorak <jezek2@advel.cz>
*
* Bullet Continuous Collision Detection and Physics Library
* Copyright (c) 2003-2008 Erwin Coumans http://www.bulletphysics.com/
*
* This software is provided 'as-is', without any express or implied warranty.
* In no event will the authors be held liable for any damages arising from
* the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
package com.bulletphysics.linearmath;
import com.bulletphysics.util.ObjectArrayList;
import cz.advel.stack.Stack;
import javax.vecmath.Vector3f;
import javax.vecmath.Vector4f;
/**
* GeometryUtil helper class provides a few methods to convert between plane
* equations and vertices.
*
* @author jezek2
*/
public class GeometryUtil {
public static boolean isPointInsidePlanes(ObjectArrayList<Vector4f> planeEquations, Vector3f point, float margin) {
int numbrushes = planeEquations.size();
for (int i = 0; i < numbrushes; i++) {
Vector4f N1 = planeEquations.getQuick(i);
float dist = VectorUtil.dot3(N1, point) + N1.w - margin;
if (dist > 0f) {
return false;
}
}
return true;
}
public static boolean areVerticesBehindPlane(Vector4f planeNormal, ObjectArrayList<Vector3f> vertices, float margin) {
int numvertices = vertices.size();
for (int i = 0; i < numvertices; i++) {
Vector3f N1 = vertices.getQuick(i);
float dist = VectorUtil.dot3(planeNormal, N1) + planeNormal.w - margin;
if (dist > 0f) {
return false;
}
}
return true;
}
private static boolean notExist(Vector4f planeEquation, ObjectArrayList<Vector4f> planeEquations) {
int numbrushes = planeEquations.size();
for (int i = 0; i < numbrushes; i++) {
Vector4f N1 = planeEquations.getQuick(i);
if (VectorUtil.dot3(planeEquation, N1) > 0.999f) {
return false;
}
}
return true;
}
public static void getPlaneEquationsFromVertices(ObjectArrayList<Vector3f> vertices, ObjectArrayList<Vector4f> planeEquationsOut) {
Vector4f planeEquation = Stack.alloc(Vector4f.class);
Vector3f edge0 = Stack.alloc(Vector3f.class), edge1 = Stack.alloc(Vector3f.class);
Vector3f tmp = Stack.alloc(Vector3f.class);
int numvertices = vertices.size();
// brute force:
for (int i = 0; i < numvertices; i++) {
Vector3f N1 = vertices.getQuick(i);
for (int j = i + 1; j < numvertices; j++) {
Vector3f N2 = vertices.getQuick(j);
for (int k = j + 1; k < numvertices; k++) {
Vector3f N3 = vertices.getQuick(k);
edge0.sub(N2, N1);
edge1.sub(N3, N1);
float normalSign = 1f;
for (int ww = 0; ww < 2; ww++) {
tmp.cross(edge0, edge1);
planeEquation.x = normalSign * tmp.x;
planeEquation.y = normalSign * tmp.y;
planeEquation.z = normalSign * tmp.z;
if (VectorUtil.lengthSquared3(planeEquation) > 0.0001f) {
VectorUtil.normalize3(planeEquation);
if (notExist(planeEquation, planeEquationsOut)) {
planeEquation.w = -VectorUtil.dot3(planeEquation, N1);
// check if inside, and replace supportingVertexOut if needed
if (areVerticesBehindPlane(planeEquation, vertices, 0.01f)) {
planeEquationsOut.add(new Vector4f(planeEquation));
}
}
}
normalSign = -1f;
}
}
}
}
}
public static void getVerticesFromPlaneEquations(ObjectArrayList<Vector4f> planeEquations, ObjectArrayList<Vector3f> verticesOut) {
Vector3f n2n3 = Stack.alloc(Vector3f.class);
Vector3f n3n1 = Stack.alloc(Vector3f.class);
Vector3f n1n2 = Stack.alloc(Vector3f.class);
Vector3f potentialVertex = Stack.alloc(Vector3f.class);
int numbrushes = planeEquations.size();
// brute force:
for (int i = 0; i < numbrushes; i++) {
Vector4f N1 = planeEquations.getQuick(i);
for (int j = i + 1; j < numbrushes; j++) {
Vector4f N2 = planeEquations.getQuick(j);
for (int k = j + 1; k < numbrushes; k++) {
Vector4f N3 = planeEquations.getQuick(k);
VectorUtil.cross3(n2n3, N2, N3);
VectorUtil.cross3(n3n1, N3, N1);
VectorUtil.cross3(n1n2, N1, N2);
if ((n2n3.lengthSquared() > 0.0001f) &&
(n3n1.lengthSquared() > 0.0001f) &&
(n1n2.lengthSquared() > 0.0001f)) {
// point P out of 3 plane equations:
// d1 ( N2 * N3 ) + d2 ( N3 * N1 ) + d3 ( N1 * N2 )
// P = -------------------------------------------------------------------------
// N1 . ( N2 * N3 )
float quotient = VectorUtil.dot3(N1, n2n3);
if (Math.abs(quotient) > 0.000001f) {
quotient = -1f / quotient;
n2n3.scale(N1.w);
n3n1.scale(N2.w);
n1n2.scale(N3.w);
potentialVertex.set(n2n3);
potentialVertex.add(n3n1);
potentialVertex.add(n1n2);
potentialVertex.scale(quotient);
// check if inside, and replace supportingVertexOut if needed
if (isPointInsidePlanes(planeEquations, potentialVertex, 0.01f)) {
verticesOut.add(new Vector3f(potentialVertex));
}
}
}
}
}
}
}
}