Serprex draws circles better than GM

Josh likes, and has decided to incorporate an equiv for ENIGMA. And the best part is, this uses no trig

Though it does run sqrt relative to the radius

//0=x 1=y 2=r

var r2,xx,yy,x1,x2;

x1=argument0-argument2//left edge

x2=argument0+argument2//right edge

r2=sqr(argument2)//To avoid computation in loop

draw_primitive_begin(pr_linelist)//This draws horizontal lines. I'm thinking it could be made to have about 70% on the loop count if I cut the drawings into 4sections

for(yy=0;yy<argument2;yy+=1){//I think this is the best loop to chose

xx=argument2-sqrt(r2-sqr(yy))//This finds half the width of the circle based on the height

draw_vertex(x1+xx,argument1-yy);draw_vertex(x2-xx,argument1-yy)//This draws the top half of the circle

draw_vertex(x1+xx,argument1+yy);draw_vertex(x2-xx,argument1+yy)//This draws the bottom half of the circle

}

draw_primitive_end()

Optimizations welcome