Here is a program that paints the entire screen red:
size (512,512);
int xval,yval;
for (xval = 0; xval < height; xval++)
{
for(yval = 0; yval < width; yval++)
{
stroke(255,0,0);
point(xval,yval);
}
}
Change the program to draw 8 pixel wide stripes of red and white
Change the program to draw 16x16 pixel checkerboards of red and white
Do something crazy to draw an awesome texture pattern
Helpful Links
FunProgramming.org - Video #53 - Create a pattern by drawing 150000 Pixels