I'm having a problem fading out an entire image slowly in openGL.  I want to do this while other things are happening.   The way I want to do it is overlay a box with alpha =1 over my "stage", thus having it slowly fade to black or another color.  

the following code behaves very differently on (I'm assuming this is the difference) an nVidia card versus an ATI card.  I'm wondering if there is- A. a way around this,  or B. an alternative method of fading out the entire image VERY quickly (performance is key here- using the pixels array is too slow)

sorry if this is off-topic. it may be a more hardware related question-  but I really can't figure it out.  maybe there's another more native method of openGL to do something like this?


here's the code:

import processing.opengl.*;
void setup(){
  size(800,600,OPENGL);
 //size(400,400,P3D);
  background(0);
}
void draw(){
 rectMode(CENTER);
 translate(0,0,0);
 fill(255,0,0,50);
 rect(mouseX, mouseY, 55, 55);
 fill(0,0,255,1);
 rect(width/2,height/2,width/2,height/2);  
}

thanks for the help!


=josh