int grow = +1;
int d = 1;
int x = 100;
int y = 100;
void setup() {
size(400, 400);
smooth();
noFill();
strokeWeight(20);
frameRate(100);
}
void draw() {
background(50);
d = (d + grow);
if (d > 40){
d = 1;
}
for(int i = 0; i < 1600; i += 20){
stroke(100);
ellipse(mouseX, mouseY, d+i, d+i);
i = i+20;
stroke(200);
ellipse(mouseX, mouseY, d+i, d+i);
}
}