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A 2D java physics engine, a port of the C++ Box2d engine. This is the core physics engine.
/*******************************************************************************
* Copyright (c) 2011, 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.
******************************************************************************/
/*
* 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.common;
import java.io.Serializable;
// updated to rev 100
/**
* A transform contains translation and rotation. It is used to represent
* the position and orientation of rigid frames.
*/
public class Transform implements Serializable {
private static final long serialVersionUID = 1L;
/** The translation caused by the transform */
public final Vec2 position;
/** A matrix representing a rotation */
public final Mat22 R;
/** The default constructor. */
public Transform() {
position = new Vec2();
R = new Mat22();
}
/** Initialize as a copy of another transform. */
public Transform(final Transform xf) {
position = xf.position.clone();
R = xf.R.clone();
}
/** Initialize using a position vector and a rotation matrix. */
public Transform(final Vec2 _position, final Mat22 _R) {
position = _position.clone();
R = _R.clone();
}
/** Set this to equal another transform. */
public final Transform set(final Transform xf) {
position.set(xf.position);
R.set(xf.R);
return this;
}
/**
* Set this based on the position and angle.
*
* @param p
* @param angle
*/
public final void set(Vec2 p, float angle) {
position.set(p);
R.set(angle);
}
/**
* Calculate the angle that the rotation matrix represents.
*/
public final float getAngle() {
return MathUtils.atan2(R.col1.y, R.col1.x);
}
/** Set this to the identity transform. */
public final void setIdentity() {
position.setZero();
R.setIdentity();
}
public final static Vec2 mul(final Transform T, final Vec2 v) {
return new Vec2(T.position.x + T.R.col1.x * v.x + T.R.col2.x * v.y, T.position.y + T.R.col1.y * v.x
+ T.R.col2.y * v.y);
}
/* djm added */
public final static void mulToOut(final Transform T, final Vec2 v, final Vec2 out) {
final float tempy = T.position.y + T.R.col1.y * v.x + T.R.col2.y * v.y;
out.x = T.position.x + T.R.col1.x * v.x + T.R.col2.x * v.y;
out.y = tempy;
}
public final static Vec2 mulTrans(final Transform T, final Vec2 v) {
final float v1x = v.x - T.position.x;
final float v1y = v.y - T.position.y;
final Vec2 b = T.R.col1;
final Vec2 b1 = T.R.col2;
return new Vec2((v1x * b.x + v1y * b.y), (v1x * b1.x + v1y * b1.y));
// return T.R.mulT(v.sub(T.position));
}
public final static void mulTransToOut(final Transform T, final Vec2 v, final Vec2 out) {
final float v1x = v.x - T.position.x;
final float v1y = v.y - T.position.y;
final Vec2 b = T.R.col1;
final Vec2 b1 = T.R.col2;
final float tempy = v1x * b1.x + v1y * b1.y;
out.x = v1x * b.x + v1y * b.y;
out.y = tempy;
}
@Override
public final String toString() {
String s = "XForm:\n";
s += "Position: " + position + "\n";
s += "R: \n" + R + "\n";
return s;
}
}