VOREStation/code/modules/lighting/lighting_turf.dm

/turf
	///Lumcount added by sources other than lighting datum objects, such as the overlay lighting component.
	var/dynamic_lumcount = 0

	var/dynamic_lighting = TRUE

	var/tmp/lighting_corners_initialised = FALSE

	var/tmp/outdoors_adjacent = FALSE
	///Our lighting object.
	var/tmp/datum/lighting_object/lighting_object
	///Lighting Corner datums.
	var/tmp/datum/lighting_corner/lighting_corner_NE
	var/tmp/datum/lighting_corner/lighting_corner_SE
	var/tmp/datum/lighting_corner/lighting_corner_SW
	var/tmp/datum/lighting_corner/lighting_corner_NW

	///Which directions does this turf block the vision of, taking into account both the turf's opacity and the movable opacity_sources.
	var/directional_opacity = NONE
	///Lazylist of movable atoms providing opacity sources.
	var/list/atom/movable/opacity_sources

// Causes any affecting light sources to be queued for a visibility update, for example a door got opened.
/turf/proc/reconsider_lights()
	lighting_corner_NE?.vis_update()
	lighting_corner_SE?.vis_update()
	lighting_corner_SW?.vis_update()
	lighting_corner_NW?.vis_update()

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

// Builds a lighting object for us, but only if our area is dynamic.
/turf/proc/lighting_build_overlay()
	if(!has_dynamic_lighting())
		return

	lighting_clear_overlay()
	new/datum/lighting_object(src)

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

	var/totallums = 0
	var/datum/lighting_corner/L
	L = lighting_corner_NE
	if (L)
		totallums += L.lum_r + L.lum_b + L.lum_g
	L = lighting_corner_SE
	if (L)
		totallums += L.lum_r + L.lum_b + L.lum_g
	L = lighting_corner_SW
	if (L)
		totallums += L.lum_r + L.lum_b + L.lum_g
	L = lighting_corner_NW
	if (L)
		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)

	totallums += dynamic_lumcount

	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 !(luminosity || dynamic_lumcount)


///Proc to add movable sources of opacity on the turf and let it handle lighting code.
/turf/proc/add_opacity_source(atom/movable/new_source)
	LAZYADD(opacity_sources, new_source)
	if(opacity)
		return
	recalculate_directional_opacity()


///Proc to remove movable sources of opacity on the turf and let it handle lighting code.
/turf/proc/remove_opacity_source(atom/movable/old_source)
	LAZYREMOVE(opacity_sources, old_source)
	if(opacity) //Still opaque, no need to worry on updating.
		return
	recalculate_directional_opacity()

///Setter for the byond luminosity var
/turf/proc/set_luminosity(new_luminosity, force)
	if(((is_outdoors() && !force) || outdoors_adjacent) && (z in fake_sunlight_zs)) //Special exception for fakesun lit tiles
		return

	luminosity = new_luminosity

///Checks planets and fake_suns to see if our turf should be handled by either
/turf/proc/check_for_sun()
	if((SSplanets && SSplanets.z_to_planet.len >= z && SSplanets.z_to_planet[z]) || (z in fake_sunlight_zs))
		return TRUE
	return FALSE

///Calculate on which directions this turfs block view.
/turf/proc/recalculate_directional_opacity()
	. = directional_opacity
	if(opacity)
		directional_opacity = ALL_CARDINALS
		if(. != directional_opacity)
			reconsider_lights()
		return
	directional_opacity = NONE
	for(var/atom/movable/opacity_source as anything in opacity_sources)
		if(opacity_source && opacity_source.flags & ON_BORDER)
			directional_opacity |= opacity_source.dir
		else //If fulltile and opaque, then the whole tile blocks view, no need to continue checking.
			directional_opacity = ALL_CARDINALS
			break
	if(. != directional_opacity && (. == ALL_CARDINALS || directional_opacity == ALL_CARDINALS))
		reconsider_lights() //The lighting system only cares whether the tile is fully concealed from all directions or not.


/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()

/turf/proc/has_dynamic_lighting()
	var/area/A = loc
	return (IS_DYNAMIC_LIGHTING(src) && IS_DYNAMIC_LIGHTING(A))