I am referring to the flicker that occurs when you do not clear the background each frame:

http://code.google.com/p/processing/issues/detail?id=146

This is something that does not affect every system,... I have several systems that work just fine, but I would like to provide a fix for those that are having the problem.

- The main problem system is using an nvidia Quadro FX 4600 video card, so it's not a cheap integrated card.
- I've tried disabling Aero (running vista x64 here)
- drivers have all been updated
- tried disabling smoothing

I really need to run this in OPENGL, because the other modes are too slow, or do not support what I am drawing. (specifically textured quad strips)

Any suggestions?

edit: These are not my actual code, but something I have broken down to the bare minimum to hopefully show the problems I am having.

First, the extremely basic code. This will flicker on machines that exhibit the bug.

1. // trying to get rid of the flicker caused by using OPENGL
   // when you do not clear the screen each frame.
   
   // this simple example will flicker on some machines
   
   import processing.opengl.*;
   
   void setup(){
     size(500,500,OPENGL);
     background(255);
   }
   
   void draw(){
     line(mouseX,mouseY,pmouseX,pmouseY);
   }
   

second, this will fix (slowly) the issue by copying the buffer at the end of each draw cycle, and pasting it at the beginning. How can I speed this up?

1. // trying to get rid of the flicker caused by using OPENGL
   // when you do not clear the screen each frame.
   
   // this appears to fix the flicker, but is not very efficient
   PImage buffer;
   
   import processing.opengl.*;
   
   void setup(){
     size(500,500,OPENGL);
     background(255);
     buffer = get(); // grab frame for the first loop through
   }
   
   void draw(){
     image(buffer,0,0);  // start of draw cycle, draw last frame
     line(mouseX,mouseY,pmouseX,pmouseY);
     buffer = get(); // end of draw cycle, grab frame
   }
   

third,... now the "fix" does not work, because the drawing occurs in mouseDragged(). Any ideas how to get this to work?
edit: ok, this will work if I do the get() right after drawing the line inside mouseDragged(), but can anyone help speed this up at all?

1. // trying to get rid of the flicker caused by using OPENGL
   // when you do not clear the screen each frame.
   
   // by moving the drawing into mouseMoved(),copying the buffer does not work,... why?
   PImage buffer;
   
   import processing.opengl.*;
   
   void setup(){
     size(500,500,OPENGL);
     background(255);
     buffer = get();
   }
   
   void draw(){
     image(buffer,0,0);  // start of draw cycle, draw last frame
     buffer = get(); // end of draw cycle, grab frame
   }
   
   void mouseDragged(){
     line(mouseX,mouseY,pmouseX,pmouseY);
   }
   

I probably used the wrong terminology in my description, but here is what I am trying to do.

I want to set up 2 arraylists, one of points, and one of lines. The line class simply refers to 2 points. I've got this working, but I'm not sure I'm using the best syntax. Here is the section I am wondering about:

1.   allPoints.add ( new myPoint (new PVector(random(width),random(height)) ) );
     allPoints.add ( new myPoint (new PVector(random(width),random(height)) ) );
    
     myPoint point1 = (myPoint) allPoints.get(allPoints.size()-1) ;
     myPoint point2 = (myPoint) allPoints.get(allPoints.size()-2) ;
    
     allLines.add (new myLine (point1,point2) );

first I create the points, then I grab them, then I use them to assign the line. Can I do this all in one step?

here is the entire code so you can see it in context. Thanks for any help.

1. 
   ArrayList allPoints;
   ArrayList allLines;
   
   //----------------------------------------------------------------------
   
   class myPoint{
     PVector pos;
    
     myPoint ( PVector _pos){ 
     pos = _pos;
     }
   }
   
   //----------------------------------------------------------------------
   
   class myLine{
     myPoint p1;
     myPoint p2;
    
     myLine (myPoint head, myPoint tail){
       p1 = head;
       p2 = tail;
     }
   }
   
   //----------------------------------------------------------------------
   
   void setup(){
     size(500,500);
     smooth();
     allPoints = new ArrayList();
     allLines = new ArrayList();
   }
   
   void draw(){
     background(128); 
     drawLines();
     drawPoints();
   }
   
   
   //----------------------------------------------------------------------
   
   void mousePressed(){
     allPoints.add ( new myPoint (new PVector(random(width),random(height)) ) );
     allPoints.add ( new myPoint (new PVector(random(width),random(height)) ) );
    
     myPoint point1 = (myPoint) allPoints.get(allPoints.size()-1) ;
     myPoint point2 = (myPoint) allPoints.get(allPoints.size()-2) ;
    
     allLines.add (new myLine (point1,point2) );
   }
   
   //----------------------------------------------------------------------
   
   void drawLines(){
     for (int i = allLines.size()-1; i >= 0; i--) {
       myLine l = (myLine) allLines.get(i);
       line (l.p1.pos.x , l.p1.pos.y,l.p2.pos.x , l.p2.pos.y );
     } 
   }
   
   //----------------------------------------------------------------------
   
   void drawPoints(){
     for (int i = allPoints.size()-1; i >= 0; i--) {
       myPoint p = (myPoint) allPoints.get(i);
       ellipse (p.pos.x , p.pos.y, 10,10);
     }
   }
   
   //----------------------------------------------------------------------