/******************************************************************************* * 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; } public void clear() { m_vertices = null; m_count = 0; } @Override public int getChildCount() { return m_count - 1; } /** * Get a child edge. * @param edge * @param index */ 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 float computeDistanceToOut(Transform xf, Vec2 p, int childIndex, Vec2 normalOut) { final EdgeShape edge = pool0; getChildEdge(edge, childIndex); return edge.computeDistanceToOut(xf, p, 0, normalOut); } @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; m_prevVertex.setZero(); m_nextVertex.setZero(); } /** * 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; } }