example.dm

#define DECAY_RATE 0.1

var/list/to_process = list(

datum/rad_handler
	var/list/sources = list()
	var/list/irradiated = list()


datum/rad_handler/process()
	for(var/turf/T in irradiated)
		irradiated[T] -= DECAY_RATE
	for(var/emitter in sources)
		radiate(emitter, emitter.rad_power, emitter.rad_range)
		to_process.cut()

datum/rad_handler/proc/radiate(source, power, range)
	var/turf/epicentre = get_turf(source)
	var/to_process = list()
	to_process[epicentre] = power
	//Gather turfs to try and irradiate
	for(var/direction in cardinal)
		var/turf/T = get_step(epicentre, direction)
		T.get_rad_area(epicentre, range, direction)

	for(var/spot in to_process)
		var/turf/origin = get_turf(epicentre)
		var/turf/dest = spot
		var/working = power
		while(origin != dest)
			origin = get_step(origin, get_dir(origin, dest))
			if(!to_process[origin])
				to_process[origin] = working
				working -= origin.rad_resistance
			else
				to_process[origin] = max(to_process[origin], working)
	
	for(var/spot in to_process)
		irradiated[spot] = (max((to_process[origin]) / (get_dist(epicentre, spot) ** 2)), irradiated[spot])

turf/proc/get_rad_area(epicentre, range, direction)
	var/testing = true //not sure if the following is necessary or not, so making sure
	if(testing)
		if(src in to_process)
			return
	to_process[src] = null
	if(get_dist(src, epicentre) >= range)
		return
	var/turf/T = get_step(src, direction)
	if(T)
		T.get_rad_area(epicentre, range, direction)
	T = get_step(src, turn(direction,90))
	if(T)
		T.get_rad_area(epicentre, range, turn(direction,90))
	T = get_step(src, turn(direction,-90))
	if(T)
		T.get_rad_area(epicentre, range, turn(direction,90))