Paradise/code/modules/lighting/lighting_turf.dm

// Causes any affecting light sources to be queued for a visibility update, for example a door got opened.
/turf/proc/reconsider_lights()
	var/datum/light_source/L
	var/thing
	for(thing in affecting_lights)
		L = thing
		L.vis_update()

/turf/proc/lighting_clear_overlay()
	if(lighting_object)
		qdel(lighting_object, TRUE)

	var/datum/lighting_corner/C
	var/thing
	for(thing in corners)
		if(!thing)
			continue
		C = thing
		C.update_active()

// Builds a lighting object for us, but only if our area is dynamic.
/turf/proc/lighting_build_overlay()
	if(lighting_object)
		qdel(lighting_object,force=TRUE) //Shitty fix for lighting objects persisting after death

	var/area/A = loc
	if(!IS_DYNAMIC_LIGHTING(A) && !light_sources)
		return

	if(!lighting_corners_initialised)
		generate_missing_corners()

	new/atom/movable/lighting_object(src)

	var/thing
	var/datum/lighting_corner/C
	var/datum/light_source/S
	for(thing in corners)
		if(!thing)
			continue
		C = thing
		if(!C.active) // We would activate the corner, calculate the lighting for it.
			for(thing in C.affecting)
				S = thing
				S.recalc_corner(C)
			C.active = TRUE

// Used to get a scaled lumcount.
/turf/proc/get_lumcount(minlum = 0, maxlum = 1)
	if(!lighting_object)
		return 1

	var/totallums = 0
	var/thing
	var/datum/lighting_corner/L
	for(thing in corners)
		if(!thing)
			continue
		L = thing
		totallums += L.lum_r + L.lum_b + L.lum_g

	totallums /= 12 // 4 corners, each with 3 channels, get the average.

	totallums = (totallums - minlum) / (maxlum - minlum)

	return CLAMP01(totallums)

// Returns a boolean whether the turf is on soft lighting.
// Soft lighting being the threshold at which point the overlay considers
// itself as too dark to allow sight and see_in_dark becomes useful.
// So basically if this returns true the tile is unlit black.
/turf/proc/is_softly_lit()
	if(!lighting_object)
		return FALSE

	return !lighting_object.luminosity

// Can't think of a good name, this proc will recalculate the has_opaque_atom variable.
/turf/proc/recalc_atom_opacity()
	has_opaque_atom = opacity
	if(!has_opaque_atom)
		for(var/atom/A in src.contents) // Loop through every movable atom on our tile PLUS ourselves (we matter too...)
			if(A.opacity)
				has_opaque_atom = TRUE
				break

/turf/Exited(atom/movable/Obj, direction)
	. = ..()

	if(Obj && Obj.opacity)
		recalc_atom_opacity() // Make sure to do this before reconsider_lights(), incase we're on instant updates.
		reconsider_lights()

/turf/proc/change_area(area/old_area, area/new_area)
	if(SSlighting.initialized)
		if(new_area.dynamic_lighting != old_area.dynamic_lighting)
			if(new_area.dynamic_lighting)
				lighting_build_overlay()
			else
				lighting_clear_overlay()
	for(var/obj/machinery/machine in contents)
		machine.reregister_machine()

/turf/proc/generate_missing_corners()
	if(!IS_DYNAMIC_LIGHTING(src) && !light_sources)
		return
	lighting_corners_initialised = TRUE
	if(!corners)
		corners = list(null, null, null, null)

	for(var/i = 1 to 4)
		if(corners[i]) // Already have a corner on this direction.
			continue

		corners[i] = new/datum/lighting_corner(src, GLOB.LIGHTING_CORNER_DIAGONAL[i])