raycastery

gistfile1.txt

note:
dx/y/z = distance to grid boundary in coordinate direction
cx/y/z = current cell
vx/y/z = ray velocities (absolute value of each coordinate)
gx/y/z = direction each ray is going
tx/y/z = time it takes to hit a boundary, or something like that
tc = time covered when firing a ray (initialised to 0)
cell_size = size of a cell


dx = vx*t
dy = vy*t
dz = vz*t

tx = dx/vx
ty = dy/vy
tz = dz/vz

compare like so:
	if dx*vy < dy*vx then tx < ty
	if dx*vz < dz*vx then tx < tz
	if dy*vz < dz*vy then ty < tz

(afaik multiply tends to be more accurate than divide)

then work out what the smallest of them is.

this would be the case where tx is 0 OR tx is the smallest:
	cx += gx
	dy -= (vy*dx)/vx
	dz -= (vz*dx)/vx
	tc += (cell_size*dx)/vx
	dx = cell_size