actually it works. i tested it and it fills your pg with black. if you want to clear pg you should try

1. pg.background(0, 0);

the second zero sets the transparency.

Cheers,
Chris

hi christian, is the bg.background(0, 0) in the correct place?

when it's just bg.background(0);, it doesn't redraw and the screen is drawn black.
when it's bg.background(0, 0);, the screen never draws. it just stays grey.

fyi, i bypassed the buffer in my project, but i'm curious about this test problem.

thanks.

PGraphics pg;

int increment = 10;

void setup() {
  size(600, 600);
  pg = createGraphics(600, 600, P2D);
}

void draw() {
  
//    background(0);
    drawEllipse();
}

void drawEllipse()
{
    for(int x = 0; x < width; x += 10)
    {
        for(int y = 0; y < height; y += 10)
        {
            pg.beginDraw();
            pg.background(0, 0);
            pg.smooth();
            pg.noFill();
            pg.stroke(255);
            pg.ellipse(increment/2 + (x * increment), increment/2 + (y * increment), 20, 20);          
            pg.endDraw();

//          smooth();
//          noFill();
//          stroke(255);
//          ellipse(increment/2 + (x * increment), increment/2 + (y * increment), 20, 20);          
          }
    }
  
    image(pg, 0, 0);
}

You are right. It doesn't work when it's inside the for-loops. It has to be cleared before all circles are drawn, outside the for-loops. It's also important that you redraw your global canvas. Here's a simple example based on your code. Hope, this helps:

1. PGraphics pg;
2. void setup() {
3.   size(600, 600);
4.   pg = createGraphics(600, 600, P2D);
5.   pg.smooth();
6.  
7.   rectMode(CENTER);
8. }
9. void draw() {
10.   background(128, 0, 0); 
11.   fill(0, 128, 0);
12.  
13.   pushMatrix();
14.   translate(width/2, height/2);
15.   rotate(frameCount*0.1);
16.   rect(0, 0, 200, 200);
17.   popMatrix();
18.  
19.   drawEllipse(mouseX, mouseY);
20. }
21. void drawEllipse(float xPos, float yPos) {
22.   pg.beginDraw();
23.   pg.background(0, 0);
24.   pg.endDraw();
25.  
26.   for(int x = -1; x < 2; x++) {
27.     for(int y = -1; y < 2; y++) {
28.       pg.beginDraw();
29.       pg.noFill();
30.       pg.stroke(255);
31.       pg.ellipse(xPos - x * 100, yPos - y * 100, 20, 20);         
32.       pg.endDraw();
33.     }
34.   }
35.  
36.   image(pg, 0, 0);
37. }

The background is red with a green rotating box. The foreground is your pg, dynamically drawn relative to the mouse position and with transparency.

Cheers,
Chris

awesome.

thanks for that.

cheers,

destro