/*******************************************************************************
* 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 chain shape is a free form sequence of line segments. The chain has two-sided collision, so you
* can use inside and outside collision. Therefore, you may use any winding order. Connectivity
* information is used to create smooth collisions. WARNING: The chain will not collide properly if
* there are self-intersections.
*
* @author Daniel
*/
public class ChainShape extends Shape {
public Vec2[] m_vertices;
public int m_count;
public final Vec2 m_prevVertex = new Vec2(), m_nextVertex = new Vec2();
public boolean m_hasPrevVertex = false, m_hasNextVertex = false;
private final EdgeShape pool0 = new EdgeShape();
public ChainShape() {
super(ShapeType.CHAIN);
m_vertices = null;
m_radius = Settings.polygonRadius;
m_count = 0;
}
@Override
public int getChildCount() {
return m_count - 1;
}
/**
* Get a child edge.
*/
public void getChildEdge(EdgeShape edge, int index) {
assert (0 <= index && index < m_count - 1);
edge.m_radius = m_radius;
final Vec2 v0 = m_vertices[index + 0];
final Vec2 v1 = m_vertices[index + 1];
edge.m_vertex1.x = v0.x;
edge.m_vertex1.y = v0.y;
edge.m_vertex2.x = v1.x;
edge.m_vertex2.y = v1.y;
if (index > 0) {
Vec2 v = m_vertices[index - 1];
edge.m_vertex0.x = v.x;
edge.m_vertex0.y = v.y;
edge.m_hasVertex0 = true;
} else {
edge.m_vertex0.x = m_prevVertex.x;
edge.m_vertex0.y = m_prevVertex.y;
edge.m_hasVertex0 = m_hasPrevVertex;
}
if (index < m_count - 2) {
Vec2 v = m_vertices[index + 2];
edge.m_vertex3.x = v.x;
edge.m_vertex3.y = v.y;
edge.m_hasVertex3 = true;
} else {
edge.m_vertex3.x = m_nextVertex.x;
edge.m_vertex3.y = m_nextVertex.y;
edge.m_hasVertex3 = m_hasNextVertex;
}
}
@Override
public boolean testPoint(Transform xf, Vec2 p) {
return false;
}
@Override
public boolean raycast(RayCastOutput output, RayCastInput input, Transform xf, int childIndex) {
assert (childIndex < m_count);
final EdgeShape edgeShape = pool0;
int i1 = childIndex;
int i2 = childIndex + 1;
if (i2 == m_count) {
i2 = 0;
}
Vec2 v = m_vertices[i1];
edgeShape.m_vertex1.x = v.x;
edgeShape.m_vertex1.y = v.y;
Vec2 v1 = m_vertices[i2];
edgeShape.m_vertex2.x = v1.x;
edgeShape.m_vertex2.y = v1.y;
return edgeShape.raycast(output, input, xf, 0);
}
@Override
public void computeAABB(AABB aabb, Transform xf, int childIndex) {
assert (childIndex < m_count);
final Vec2 lower = aabb.lowerBound;
final Vec2 upper = aabb.upperBound;
int i1 = childIndex;
int i2 = childIndex + 1;
if (i2 == m_count) {
i2 = 0;
}
final Vec2 vi1 = m_vertices[i1];
final Vec2 vi2 = m_vertices[i2];
final Rot xfq = xf.q;
final Vec2 xfp = xf.p;
float v1x = (xfq.c * vi1.x - xfq.s * vi1.y) + xfp.x;
float v1y = (xfq.s * vi1.x + xfq.c * vi1.y) + xfp.y;
float v2x = (xfq.c * vi2.x - xfq.s * vi2.y) + xfp.x;
float v2y = (xfq.s * vi2.x + xfq.c * vi2.y) + xfp.y;
lower.x = v1x < v2x ? v1x : v2x;
lower.y = v1y < v2y ? v1y : v2y;
upper.x = v1x > v2x ? v1x : v2x;
upper.y = v1y > v2y ? v1y : v2y;
}
@Override
public void computeMass(MassData massData, float density) {
massData.mass = 0.0f;
massData.center.setZero();
massData.I = 0.0f;
}
@Override
public Shape clone() {
ChainShape clone = new ChainShape();
clone.createChain(m_vertices, m_count);
clone.m_prevVertex.set(m_prevVertex);
clone.m_nextVertex.set(m_nextVertex);
clone.m_hasPrevVertex = m_hasPrevVertex;
clone.m_hasNextVertex = m_hasNextVertex;
return clone;
}
/**
* Create a loop. This automatically adjusts connectivity.
*
* @param vertices an array of vertices, these are copied
* @param count the vertex count
*/
public void createLoop(final Vec2[] vertices, int count) {
assert (m_vertices == null && m_count == 0);
assert (count >= 3);
m_count = count + 1;
m_vertices = new Vec2[m_count];
for (int i = 1; i < count; i++) {
Vec2 v1 = vertices[i - 1];
Vec2 v2 = vertices[i];
// If the code crashes here, it means your vertices are too close together.
if (MathUtils.distanceSquared(v1, v2) < Settings.linearSlop * Settings.linearSlop) {
throw new RuntimeException("Vertices of chain shape are too close together");
}
}
for (int i = 0; i < count; i++) {
m_vertices[i] = new Vec2(vertices[i]);
}
m_vertices[count] = new Vec2(m_vertices[0]);
m_prevVertex.set(m_vertices[m_count - 2]);
m_nextVertex.set(m_vertices[1]);
m_hasPrevVertex = true;
m_hasNextVertex = true;
}
/**
* Create a chain with isolated end vertices.
*
* @param vertices an array of vertices, these are copied
* @param count the vertex count
*/
public void createChain(final Vec2 vertices[], int count) {
assert (m_vertices == null && m_count == 0);
assert (count >= 2);
m_count = count;
m_vertices = new Vec2[m_count];
for (int i = 1; i < m_count; i++) {
Vec2 v1 = vertices[i - 1];
Vec2 v2 = vertices[i];
// If the code crashes here, it means your vertices are too close together.
if (MathUtils.distanceSquared(v1, v2) < Settings.linearSlop * Settings.linearSlop) {
throw new RuntimeException("Vertices of chain shape are too close together");
}
}
for (int i = 0; i < m_count; i++) {
m_vertices[i] = new Vec2(vertices[i]);
}
m_hasPrevVertex = false;
m_hasNextVertex = false;
}
/**
* Establish connectivity to a vertex that precedes the first vertex. Don't call this for loops.
*
* @param prevVertex
*/
public void setPrevVertex(final Vec2 prevVertex) {
m_prevVertex.set(prevVertex);
m_hasPrevVertex = true;
}
/**
* Establish connectivity to a vertex that follows the last vertex. Don't call this for loops.
*
* @param nextVertex
*/
public void setNextVertex(final Vec2 nextVertex) {
m_nextVertex.set(nextVertex);
m_hasNextVertex = true;
}
}