15

size(400,400);
background(10);
strokeWeight(1);
stroke(255);
smooth();
float x = width - 1;
float y = height - 1;
float y2 =0, x2 = 0;
float h =0, w = 0;

float wStep = 3.0;
float hStep = 3.0;
noFill();
beginShape();
vertex(x-w,y2+h);
for(int i = min(width, height); i > min(width, height)/2; i -= max(wStep, hStep)){
vertex(x-w,y-h);
vertex(x2+w,y-h);
vertex(x2+w,y2+h);
w += wStep;
vertex(x-w,y2+h);
h += hStep;
}
endShape();