import javax.media.opengl.*;
import com.sun.opengl.util.FPSAnimator;

GLCanvas canvas;

void setup() {
 size(400, 300);
 
 canvas = new GLCanvas();
 canvas.setSize(200, 200);
 canvas.addGLEventListener(new GLRenderer());
 FPSAnimator animator = new FPSAnimator(canvas, 60);
 animator.start();
 
 add(canvas);
 
}

void draw() {
 background(50);
 fill(255);
 rect(10,10,frameCount%100,10);
}

class GLRenderer implements GLEventListener {
 GL gl;

 public void init(GLAutoDrawable drawable) {
   this.gl = drawable.getGL();
   gl.glClearColor(1, 0, 0, 0);  
   canvas.setLocation(100, 80);    
 }

 public void display(GLAutoDrawable drawable) {
   gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT );
   gl.glColor3f(1, 1, 1);
   gl.glRectf(-0.8, 0.8, frameCount%100/100f -0.8, 0.7);
 }
 
 public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {
 }

 public void displayChanged(GLAutoDrawable drawable, boolean modeChanged, boolean deviceChanged) {
 }
}