OrbitAnimation.java

package br.com.etyllica.core.animation.script;

import br.com.etyllica.layer.Layer;


public class OrbitAnimation extends SingleIntervalAnimation {

	private float centerX = 0, centerY = 0;
	private float tx, ty, tw, th;
	
	public OrbitAnimation(long time) {
		super(time);
	}

	public OrbitAnimation(long delay, long time) {
		super(delay, time);
	}

	public OrbitAnimation(Layer target, long time) {
		super(target, time);
	}
	
	public OrbitAnimation(Layer target) {
		super(target);
	}
	
	@Override
	public OrbitAnimation during(long time) {
		super.during(time);
		return this;
	}
	
	public OrbitAnimation around(float centerX, float centerY) {
		this.centerX = centerX;
		this.centerY = centerY;
		
		return this;
	}
	
	@Override
	public void setTarget(Layer target) {
		super.setTarget(target);
		
		tx = target.getX();
		ty = target.getY();
		tw = target.getW()/2;
		th = target.getH()/2;
	}
	
	@Override
	public void update(double value) {

		double angle = value*Math.PI/180;

		double s = Math.sin(angle);
		double c = Math.cos(angle);

		// translate point back to origin:
		float px = tx+tw-centerX;
		float py = ty+th-centerY;

		// rotate point
		double xnew = px * c - py * s;
		double ynew = px * s + py * c;

		// translate point back:
		target.setX((int)(xnew + centerX - tw));
		target.setY((int)(ynew + centerY - th));
	}

}