/*
* Phys2D - a 2D physics engine based on the work of Erin Catto.
*
* This source is provided under the terms of the BSD License.
*
* Copyright (c) 2006, Phys2D
* 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.
* * Neither the name of the Phys2D/New Dawn Software nor the names of
* its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 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 OWNER 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 net.phys2d.raw.collide;
import net.phys2d.math.MathUtil;
import net.phys2d.math.Vector2f;
import net.phys2d.raw.Body;
import net.phys2d.raw.Contact;
import net.phys2d.raw.shapes.Box;
import net.phys2d.raw.shapes.Circle;
import net.phys2d.raw.shapes.Line;
/**
* A collider for boxes hitting circles. Box = bodyA, Circle = bodyB
*
* The create() method is used as a factor although since this collider
* is currently stateless a single instance is returned.
*
* @author Kevin Glass
*/
public strictfp class BoxCircleCollider implements Collider {
/**
* @see net.phys2d.raw.collide.Collider#collide(net.phys2d.raw.Contact[], net.phys2d.raw.Body, net.phys2d.raw.Body)
*/
public int collide(Contact[] contacts, Body boxBody, Body circleBody) {
float x1 = boxBody.getPosition().getX();
float y1 = boxBody.getPosition().getY();
float x2 = circleBody.getPosition().getX();
float y2 = circleBody.getPosition().getY();
boolean touches = boxBody.getShape().getBounds().touches(x1,y1,circleBody.getShape().getBounds(),x2,y2);
if (!touches) {
return 0;
}
Box box = (Box) boxBody.getShape();
Circle circle = (Circle) circleBody.getShape();
Vector2f[] pts = box.getPoints(boxBody.getPosition(), boxBody.getRotation());
Line[] lines = new Line[4];
lines[0] = new Line(pts[0],pts[1]);
lines[1] = new Line(pts[1],pts[2]);
lines[2] = new Line(pts[2],pts[3]);
lines[3] = new Line(pts[3],pts[0]);
float r2 = circle.getRadius() * circle.getRadius();
int closest = -1;
float closestDistance = Float.MAX_VALUE;
for (int i=0;i<4;i++) {
float dis = lines[i].distanceSquared(circleBody.getPosition());
if (dis < r2) {
if (closestDistance > dis) {
closestDistance = dis;
closest = i;
}
}
}
if (closest > -1) {
float dis = (float) Math.sqrt(closestDistance);
contacts[0].setSeparation(dis - circle.getRadius());
// this should really be where the edge and the line
// between the two elements cross?
Vector2f contactPoint = new Vector2f();
lines[closest].getClosestPoint(circleBody.getPosition(), contactPoint);
Vector2f normal = MathUtil.sub(circleBody.getPosition(), contactPoint);
normal.normalise();
contacts[0].setNormal(normal);
contacts[0].setPosition(contactPoint);
contacts[0].setFeature(new FeaturePair());
return 1;
}
return 0;
}
}