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/*
* Copyright (c) 2010-2016 William Bittle http://www.dyn4j.org/
* 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 dyn4j 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
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*/
package org.dyn4j.collision.narrowphase;
import org.dyn4j.geometry.Convex;
import org.dyn4j.geometry.Shape;
import org.dyn4j.geometry.Transform;
import org.dyn4j.geometry.Vector2;
/**
* Represents the Minkowski sum of the given {@link Convex} {@link Shape}s.
*
* This class is used by the {@link Gjk} and {@link Epa} classes to compute support points.
*
* This class doesn't actually compute the Minkowski sum.
* @author William Bittle
* @version 3.2.0
* @since 1.0.0
*/
public class MinkowskiSum {
/** The first {@link Convex} */
final Convex convex1;
/** The second {@link Convex} */
final Convex convex2;
/** The first {@link Convex}'s {@link Transform} */
final Transform transform1;
/** The second {@link Convex}'s {@link Transform} */
final Transform transform2;
/**
* Full constructor.
* @param convex1 the first {@link Convex}
* @param transform1 the first {@link Convex}'s {@link Transform}
* @param convex2 the second {@link Convex}
* @param transform2 the second {@link Convex}'s {@link Transform}
*/
public MinkowskiSum(Convex convex1, Transform transform1, Convex convex2, Transform transform2) {
this.convex1 = convex1;
this.convex2 = convex2;
this.transform1 = transform1;
this.transform2 = transform2;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("MinkowskiSum[Convex1=").append(this.convex1.getId())
.append("|Transform1=").append(this.transform1)
.append("|Convex2=").append(this.convex2.getId())
.append("|Transform2=").append(this.transform2)
.append("]");
return sb.toString();
}
/**
* Returns the farthest point in the Minkowski sum given the direction.
* @param direction the search direction
* @return {@link Vector2} the point farthest in the Minkowski sum in the given direction
*/
public final Vector2 getSupportPoint(Vector2 direction) {
// get the farthest point in the given direction in convex1
Vector2 point1 = this.convex1.getFarthestPoint(direction, this.transform1);
direction.negate();
// get the farthest point in the opposite direction in convex2
Vector2 point2 = this.convex2.getFarthestPoint(direction, this.transform2);
direction.negate();
// return the Minkowski sum point
return point1.subtract(point2);
}
/**
* Returns the farthest point, and the support points in the shapes, in the Minkowski sum given the direction.
* @param direction the search direction
* @return {@link MinkowskiSumPoint} the point farthest in the Minkowski sum in the given direction
*/
public final MinkowskiSumPoint getSupportPoints(Vector2 direction) {
// get the farthest point in the given direction in convex1
Vector2 point1 = this.convex1.getFarthestPoint(direction, this.transform1);
direction.negate();
// get the farthest point in the opposite direction in convex2
Vector2 point2 = this.convex2.getFarthestPoint(direction, this.transform2);
direction.negate();
// set the Minkowski sum point given the support points
return new MinkowskiSumPoint(point1, point2);
}
/**
* Returns the first {@link Convex} {@link Shape}.
* @return {@link Convex}
*/
public Convex getConvex1() {
return this.convex1;
}
/**
* Returns the second {@link Convex} {@link Shape}.
* @return {@link Convex}
*/
public Convex getConvex2() {
return this.convex2;
}
/**
* Returns the first {@link Convex} {@link Shape}'s {@link Transform}.
* @return {@link Transform}
*/
public Transform getTransform1() {
return this.transform1;
}
/**
* Returns the second {@link Convex} {@link Shape}'s {@link Transform}.
* @return {@link Transform}
*/
public Transform getTransform2() {
return this.transform2;
}
}