Genuary 2023 Day 21 - Persian Rug

-- genuary #21 2023
-- persian rug
-- by carson kompon
-- huge thanks to piter pasma's explanation video
function dist(x,y)
	return sqrt((x*x+y*y))
end

function edge(x,y)
	if x>0 and y>0 then
		return dist(x,y)
	elseif x>y then
		return x
	end
	return y
end

function sdf_rect(x,y,cx,cy,w,h)
	x-=cx
	y-=cy
	return edge(abs(x)-w,abs(y)-h)
end

function sdf_circle(x,y,cx,cy,r)
	x-=cx
	y-=cy
	return dist(x,y) - r
end

function sdf(x,y)
	dd = 1.5
	circle = sdf_circle(x,y,cos(t()/4+.5)/dd,sin(t()/16+.5)/dd,.001)
	circle = (abs(circle)-.1)*1.2
	box = sdf_rect(x,y,0,0,.9,.75)
	return max(-circle,box)
end

pal({[0]=0,128,133,141,133,0,0,0,12,140,1,129,130,132,9,10},1)

::_::
	x=rnd(2)-1
	y=rnd(2)-1
	d=sdf(x,y)
	c=0
	if(d<0)c=d*16
	circfill((x+1)*64,(y+1)*64,1,c)
goto _