-----------------
 Sprite rotation
-----------------


sx
The x coordinate of the upper left corner of the rectangle in the sprite sheet.
sy
The y coordinate of the upper left corner of the rectangle in the sprite sheet.
swh
The size of the sprite to draw, always square
dx
The x coordinate of the upper left corner of the rectangle area of the screen.
dy
The y coordinate of the upper left corner of the rectangle area of the screen.
rot
How much to rotate this sprite by, ranging from 0 to 1


function spr_rot(sx,sy,swh,dx,dy,rot)
	local s=sin(rot)
	local c=cos(rot)
	local size = swh/2
	local _b=(s*s+c*c)
	local w = sqrt(size^2*2)
	for y=-w,w do
		for x=-w,w do
			local ox=(s*y+c*x)/_b+size
			local oy=(-s*x+c*y)/_b+size
			if ox<swh and oy<swh and ox>0 and oy>0 then
				local col=sget(ox+sx,oy+sy)
				if (col>0) _pset(dx+x,dy+y,col)
			end
		end
	end
end