/*******************************************************************************
* Copyright (c) 2013, Daniel Murphy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
******************************************************************************/
package org.jbox2d.collision.shapes;
import org.jbox2d.collision.AABB;
import org.jbox2d.collision.RayCastInput;
import org.jbox2d.collision.RayCastOutput;
import org.jbox2d.common.MathUtils;
import org.jbox2d.common.Rot;
import org.jbox2d.common.Settings;
import org.jbox2d.common.Transform;
import org.jbox2d.common.Vec2;
/**
* A line segment (edge) shape. These can be connected in chains or loops to other edge shapes. The
* connectivity information is used to ensure correct contact normals.
*
* @author Daniel
*/
public class EdgeShape extends Shape {
/**
* edge vertex 1
*/
public final Vec2 m_vertex1 = new Vec2();
/**
* edge vertex 2
*/
public final Vec2 m_vertex2 = new Vec2();
/**
* optional adjacent vertex 1. Used for smooth collision
*/
public final Vec2 m_vertex0 = new Vec2();
/**
* optional adjacent vertex 2. Used for smooth collision
*/
public final Vec2 m_vertex3 = new Vec2();
public boolean m_hasVertex0 = false, m_hasVertex3 = false;
public EdgeShape() {
super(ShapeType.EDGE);
m_radius = Settings.polygonRadius;
}
@Override
public int getChildCount() {
return 1;
}
public void set(Vec2 v1, Vec2 v2) {
m_vertex1.set(v1);
m_vertex2.set(v2);
m_hasVertex0 = m_hasVertex3 = false;
}
@Override
public boolean testPoint(Transform xf, Vec2 p) {
return false;
}
// for pooling
private final Vec2 normal = new Vec2();
@Override
public float computeDistanceToOut(Transform xf, Vec2 p, int childIndex, Vec2 normalOut) {
float xfqc = xf.q.c;
float xfqs = xf.q.s;
float xfpx = xf.p.x;
float xfpy = xf.p.y;
float v1x = (xfqc * m_vertex1.x - xfqs * m_vertex1.y) + xfpx;
float v1y = (xfqs * m_vertex1.x + xfqc * m_vertex1.y) + xfpy;
float v2x = (xfqc * m_vertex2.x - xfqs * m_vertex2.y) + xfpx;
float v2y = (xfqs * m_vertex2.x + xfqc * m_vertex2.y) + xfpy;
float dx = p.x - v1x;
float dy = p.y - v1y;
float sx = v2x - v1x;
float sy = v2y - v1y;
float ds = dx * sx + dy * sy;
if (ds > 0) {
float s2 = sx * sx + sy * sy;
if (ds > s2) {
dx = p.x - v2x;
dy = p.y - v2y;
} else {
dx -= ds / s2 * sx;
dy -= ds / s2 * sy;
}
}
float d1 = MathUtils.sqrt(dx * dx + dy * dy);
if (d1 > 0) {
normalOut.x = 1 / d1 * dx;
normalOut.y = 1 / d1 * dy;
} else {
normalOut.x = 0;
normalOut.y = 0;
}
return d1;
}
// p = p1 + t * d
// v = v1 + s * e
// p1 + t * d = v1 + s * e
// s * e - t * d = p1 - v1
@Override
public boolean raycast(RayCastOutput output, RayCastInput input, Transform xf, int childIndex) {
float tempx, tempy;
final Vec2 v1 = m_vertex1;
final Vec2 v2 = m_vertex2;
final Rot xfq = xf.q;
final Vec2 xfp = xf.p;
// Put the ray into the edge's frame of reference.
// b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
// b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
tempx = input.p1.x - xfp.x;
tempy = input.p1.y - xfp.y;
final float p1x = xfq.c * tempx + xfq.s * tempy;
final float p1y = -xfq.s * tempx + xfq.c * tempy;
tempx = input.p2.x - xfp.x;
tempy = input.p2.y - xfp.y;
final float p2x = xfq.c * tempx + xfq.s * tempy;
final float p2y = -xfq.s * tempx + xfq.c * tempy;
final float dx = p2x - p1x;
final float dy = p2y - p1y;
// final Vec2 normal = pool2.set(v2).subLocal(v1);
// normal.set(normal.y, -normal.x);
normal.x = v2.y - v1.y;
normal.y = v1.x - v2.x;
normal.normalize();
final float normalx = normal.x;
final float normaly = normal.y;
// q = p1 + t * d
// dot(normal, q - v1) = 0
// dot(normal, p1 - v1) + t * dot(normal, d) = 0
tempx = v1.x - p1x;
tempy = v1.y - p1y;
float numerator = normalx * tempx + normaly * tempy;
float denominator = normalx * dx + normaly * dy;
if (denominator == 0.0f) {
return false;
}
float t = numerator / denominator;
if (t < 0.0f || 1.0f < t) {
return false;
}
// Vec2 q = p1 + t * d;
final float qx = p1x + t * dx;
final float qy = p1y + t * dy;
// q = v1 + s * r
// s = dot(q - v1, r) / dot(r, r)
// Vec2 r = v2 - v1;
final float rx = v2.x - v1.x;
final float ry = v2.y - v1.y;
final float rr = rx * rx + ry * ry;
if (rr == 0.0f) {
return false;
}
tempx = qx - v1.x;
tempy = qy - v1.y;
// float s = Vec2.dot(pool5, r) / rr;
float s = (tempx * rx + tempy * ry) / rr;
if (s < 0.0f || 1.0f < s) {
return false;
}
output.fraction = t;
if (numerator > 0.0f) {
// output.normal = -b2Mul(xf.q, normal);
output.normal.x = -xfq.c * normal.x + xfq.s * normal.y;
output.normal.y = -xfq.s * normal.x - xfq.c * normal.y;
} else {
// output->normal = b2Mul(xf.q, normal);
output.normal.x = xfq.c * normal.x - xfq.s * normal.y;
output.normal.y = xfq.s * normal.x + xfq.c * normal.y;
}
return true;
}
@Override
public void computeAABB(AABB aabb, Transform xf, int childIndex) {
final Vec2 lowerBound = aabb.lowerBound;
final Vec2 upperBound = aabb.upperBound;
final Rot xfq = xf.q;
final float v1x = (xfq.c * m_vertex1.x - xfq.s * m_vertex1.y) + xf.p.x;
final float v1y = (xfq.s * m_vertex1.x + xfq.c * m_vertex1.y) + xf.p.y;
final float v2x = (xfq.c * m_vertex2.x - xfq.s * m_vertex2.y) + xf.p.x;
final float v2y = (xfq.s * m_vertex2.x + xfq.c * m_vertex2.y) + xf.p.y;
lowerBound.x = v1x < v2x ? v1x : v2x;
lowerBound.y = v1y < v2y ? v1y : v2y;
upperBound.x = v1x > v2x ? v1x : v2x;
upperBound.y = v1y > v2y ? v1y : v2y;
lowerBound.x -= m_radius;
lowerBound.y -= m_radius;
upperBound.x += m_radius;
upperBound.y += m_radius;
}
@Override
public void computeMass(MassData massData, float density) {
massData.mass = 0.0f;
massData.center.set(m_vertex1).addLocal(m_vertex2).mulLocal(0.5f);
massData.I = 0.0f;
}
@Override
public Shape clone() {
EdgeShape edge = new EdgeShape();
edge.m_radius = this.m_radius;
edge.m_hasVertex0 = this.m_hasVertex0;
edge.m_hasVertex3 = this.m_hasVertex3;
edge.m_vertex0.set(this.m_vertex0);
edge.m_vertex1.set(this.m_vertex1);
edge.m_vertex2.set(this.m_vertex2);
edge.m_vertex3.set(this.m_vertex3);
return edge;
}
}