/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
package com.badlogic.gdx.physics.box2d;
import com.badlogic.gdx.math.Vector2;
/** Encodes a Box2D transform. We are lazy so we only store a 4 float wide array. First two floats are the position of the
* b2Transform struct. Next two floats are the cosine and sine of the rotation angle.
* @author mzechner */
public class Transform {
public static final int POS_X = 0;
public static final int POS_Y = 1;
public static final int COS = 2;
public static final int SIN = 3;
public float[] vals = new float[4];
private Vector2 position = new Vector2();
private Vector2 orientation = new Vector2();
public Transform () {
}
/** Constructs a new Transform instance with the given position and angle
* @param position the position
* @param angle the angle in radians */
public Transform (Vector2 position, float angle) {
setPosition(position);
setRotation(angle);
}
/** Constructs a new Transform instance with the given position and orientation
* @param position the position
* @param orientation where the transform is pointing*/
public Transform (Vector2 position, Vector2 orientation) {
setPosition(position);
setOrientation(orientation);
}
/** Transforms the given vector by this transform
* @param v the vector */
public Vector2 mul (Vector2 v) {
float x = vals[POS_X] + vals[COS] * v.x + -vals[SIN] * v.y;
float y = vals[POS_Y] + vals[SIN] * v.x + vals[COS] * v.y;
v.x = x;
v.y = y;
return v;
}
/** @return the position, modification of the vector has no effect on the Transform */
public Vector2 getPosition () {
return position.set(vals[0], vals[1]);
}
/** Sets the rotation of this transform
* @param angle angle in radians */
public void setRotation (float angle) {
float c = (float)Math.cos(angle), s = (float)Math.sin(angle);
vals[COS] = c;
vals[SIN] = s;
}
public float getRotation () {
return (float)Math.atan2(vals[SIN], vals[COS]);
}
/** @return A vector 2 pointing to where the body is facing */
public Vector2 getOrientation () {
return orientation.set(vals[COS], vals[SIN]);
}
/** @return Set where the body should "look at" */
public void setOrientation (Vector2 orientation) {
this.vals[COS] = orientation.x;
this.vals[SIN] = orientation.y;
}
/** Sets the position of this transform
* @param pos the position */
public void setPosition (Vector2 pos) {
this.vals[POS_X] = pos.x;
this.vals[POS_Y] = pos.y;
}
}