PolygonDef.java

/*
 * JBox2D - A Java Port of Erin Catto's Box2D
 * 
 * JBox2D homepage: http://jbox2d.sourceforge.net/
 * Box2D homepage: http://www.box2d.org
 * 
 * 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 org.jbox2d.collision.shapes;

//Updated to rev 56 of b2Shape.cpp/.h
// -> rev 97 of b2PolygonShape.cpp/.h

import java.util.ArrayList;
import java.util.List;

import org.jbox2d.collision.FilterData;
import org.jbox2d.common.Vec2;
import org.jbox2d.common.XForm;

/**
 * Convex polygon. The vertices must be in CCW order for a right-handed
 * coordinate system with the z-axis coming out of the screen.
 * Add vertices using PolygonDef.add(Vec2),
 * and create the polygon shape using Body::createShape(ShapeDef).
 */
public class PolygonDef extends ShapeDef {

	/**
	 * The polygon vertices in local coordinates.
	 * <BR><BR>
	 * Accessing this field is discouraged - it remains
	 * public for the moment, but that is likely to change.
	 * Please use addVertex(Vec2) and getVertexList/Array
	 * instead to add to or inspect the current vertices.
	 */
	public List<Vec2> vertices;

	public void set(final PolygonDef copyMe) {
		this.density = copyMe.density;
		this.filter = new FilterData();
		this.filter.set(copyMe.filter);
		this.friction = copyMe.friction;
		this.isSensor = copyMe.isSensor;
		this.restitution = copyMe.restitution;
		this.type = copyMe.type;
		this.userData = copyMe.userData;
		this.vertices = new ArrayList<Vec2>();
		for(int i=0; i<copyMe.vertices.size(); ++i) {
			this.addVertex(copyMe.vertices.get(i).clone());
		}
	}

	public PolygonDef() {
		type = ShapeType.POLYGON_SHAPE;
		vertices = new ArrayList<Vec2>();
	}

	/** Add a vertex to the polygon. */
	public void addVertex(final Vec2 v) {
		vertices.add(v);
	}

	/** Removes all vertices. */
	public void clearVertices() {
		vertices.clear();
	}

	/** Return the vertex list as an array. */
	public Vec2[] getVertexArray() {
		return vertices.toArray(new Vec2[0]);
	}

	/** Return the vertex list as a List<Vec2>. */
	public List<Vec2> getVertexList() {
		return vertices;
	}

	/**
	 * Build vertices to represent an axis-aligned box.
	 * @param hx the half-width.
	 * @param hy the half-height.
	 */
	public void setAsBox(final float hx, final float hy) {
		vertices.clear();
		vertices.add(new Vec2(-hx, -hy));
		vertices.add(new Vec2(hx, -hy));
		vertices.add(new Vec2(hx, hy));
		vertices.add(new Vec2(-hx, hy));
	}

	/**
	 * Build vertices to represent an oriented box.
	 * @param hx the half-width.
	 * @param hy the half-height.
	 * @param center the center of the box in local coordinates.
	 * @param angle the rotation of the box in local coordinates.
	 */
	public void setAsBox(final float hx, final float hy, final Vec2 center, final float angle) {
		setAsBox(hx, hy);
		final XForm xf = new XForm();
		xf.position.set(center);
		xf.R.set(angle);
		// djm optimized. I'm leaving the XForm creation, it doesn't matter here
		for (int i = 0; i < vertices.size(); ++i) {
			XForm.mulToOut(xf, vertices.get(i), vertices.get(i));
		}
	}

	/** Return the number of vertices. */
	public int getVertexCount() {
		return vertices.size();
	}
}