LNJumpParabolaBy.java

/**
 * Copyright 2008 - 2012
 * 
 * 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.
 * 
 * @project loon
 * @author cping
 * @email：javachenpeng@yahoo.com
 * @version 0.3.3
 */
package loon.action.sprite.node;

import loon.core.geom.Vector2f;

public class LNJumpParabolaBy extends LNAction {

	LNJumpParabolaBy() {

	}

	public float _a;

	public float _b;

	public float _c;

	public Vector2f _delta;

	public float _height;

	public Vector2f _refPoint;

	public Vector2f _startPosition;

	public static LNJumpParabolaBy Action(float duration, Vector2f position,
			Vector2f refPoint) {
		LNJumpParabolaBy by = new LNJumpParabolaBy();
		by._delta = position;
		by._duration = duration;
		by._refPoint = refPoint;
		return by;
	}

	public void setTarget(LNNode node) {
		super._firstTick = true;
		super._isEnd = false;
		super._target = node;
		this._startPosition = super._target._position;
		this._a = ((this._refPoint.y / this._refPoint.x) - (this._delta.y / this._delta.x))
				/ (this._refPoint.x - this._delta.x);
		this._b = (this._delta.y / this._delta.x)
				- ((this._delta.x + (2f * this._startPosition.x)) * this._a);
		this._c = (this._startPosition.y - ((this._a * this._startPosition.x) * this._startPosition.x))
				- (this._b * this._startPosition.x);
	}

	public void update(float t) {
		float num = (t * this._delta.x) + this._startPosition.x;
		float x = num;
		float y = (((this._a * x) * x) + (this._b * x)) + this._c;
		super._target.setPosition(x, y);
	}

	public LNAction copy() {
		return Action(_duration, _delta, _refPoint);
	}

	public LNAction reverse() {
		return Action(_duration, _delta.negate(), _refPoint);
	}
}