Loops for Drawing

You can, of course, use the loop variable to draw things.

Gradient

size(256,100); int x; for (x=0;x < 256;x++) { stroke(x); line (x,0,x,100); }
Here, 'x' means both the x coordinate of a line AND the stroke value. You can also generate other variables based on the loop variable.

Row of Dots

size(600,400); int i; int x; int s; for (i=0 ; i < 10 ; i++) { x=i * 50; s=i * 2; ellipse(x,200,s,s); }

Moire

void setup() { size(700,500); } void draw() { int x1,y1; int x2,y2; background(0); stroke(255,255,255,128); for (y1=0;y1< 500;y1=y1+10) { y2=500-y1; line(0,y1,700,y2); } for (x1=0;x1<700;x1=x1+10) { x2=700-x1; line(x1,0,x2,500); } }