/*
* Copyright 2009 Hao Nguyen
*
* 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 gwt.g2d.client.demo;
import gwt.g2d.client.graphics.Color;
import gwt.g2d.client.graphics.DirectShapeRenderer;
import gwt.g2d.client.graphics.KnownColor;
import gwt.g2d.client.math.Vector2;
import java.util.ArrayList;
import java.util.List;
import com.google.gwt.user.client.Random;
import com.google.gwt.user.client.ui.Panel;
/**
* Particles animation demo.
*
* @author hao1300@gmail.com
*/
public class ParticlesDemo extends AbstractDemo {
private static final int NUM_PARTICLES = 100;
private final List<Particle> particles = new ArrayList<Particle>(NUM_PARTICLES);
private DirectShapeRenderer shapeRenderer;
public ParticlesDemo(Panel parentContainer) {
super("Particles Demo", parentContainer);
}
@Override
public void initialize() {
add(getPrimarySurface());
shapeRenderer = new DirectShapeRenderer(getPrimarySurface());
particles.clear();
for (int i = 0; i < NUM_PARTICLES; i++) {
particles.add(new Particle(
new Vector2(Random.nextInt(WIDTH), Random.nextInt(HEIGHT)),
new Vector2(Math.random(), Math.random()).normalize(),
new Color(Random.nextInt(256),
Random.nextInt(256),
Random.nextInt(256),
Math.random())));
}
}
@Override
public void update() {
for (Particle p : particles) {
Vector2 pos = p.getPosition();
Vector2 vel = p.getVelocity();
if (pos.getX() < 0) {
vel.setX(Math.abs(vel.getX()));
} else if (pos.getX() >= WIDTH) {
vel.setX(-Math.abs(vel.getX()));
}
if (pos.getY() < 0) {
vel.setY(Math.abs(vel.getY()));
} else if (pos.getY() >= HEIGHT) {
vel.setY(-Math.abs(vel.getY()));
}
pos.mutableAdd(p.getVelocity());
}
draw();
}
/**
* Draws the particles.
*/
private void draw() {
getPrimarySurface().clear().fillBackground(KnownColor.BLACK);
for (Particle p : particles) {
getPrimarySurface().save()
.setFillStyle(p.getColor());
shapeRenderer.beginPath()
.moveTo(p.getPosition())
.drawCircle(p.getPosition(), 2)
.closePath()
.fill();
getPrimarySurface().restore();
}
}
/**
* Simple particle class.
*
* @author hao1300@gmail.com
*/
private static class Particle {
private final Vector2 position, velocity;
private final Color color;
public Particle(Vector2 position, Vector2 velocity, Color color) {
this.position = position;
this.velocity = velocity;
this.color = color;
}
public final Color getColor() {
return color;
}
public final Vector2 getPosition() {
return position;
}
public final Vector2 getVelocity() {
return velocity;
}
}
}