Inline some lighting stuff (#2929)

Inlines some really frequently called lighting procs, maybe will speed up lighting updates a bit.

code/modules/lighting/lighting_source.dm

@@ -328,6 +328,7 @@
 	var/thing
 	var/datum/lighting_corner/C
 	var/turf/T
+	var/list/Tcorners
 	var/Sx = source_turf.x
 	var/Sy = source_turf.y
 
@@ -336,7 +337,23 @@
 		if (light_angle && check_light_cone(T.x, T.y))
 			continue
 
-		for (thing in T.get_corners())
+		if (T.dynamic_lighting || T.light_sources)
+			Tcorners = T.corners
+			if (!T.lighting_corners_initialised)
+				T.lighting_corners_initialised = TRUE
+
+				if (!Tcorners)
+					T.corners = list(null, null, null, null)
+					Tcorners = T.corners
+
+				for (var/i = 1 to 4)
+					if (Tcorners[i])
+						continue
+
+					Tcorners[i] = new /datum/lighting_corner(T, LIGHTING_CORNER_DIAGONAL[i])
+
+			if (!T.has_opaque_atom)
+				for (thing in Tcorners)
 					C = thing
 					corners[C] = 0
 

code/modules/lighting/lighting_source_novis.dm

@@ -61,6 +61,7 @@
 	var/datum/lighting_corner/C
 	var/turf/T
 	var/Tthing
+	var/list/Tcorners
 	var/Sx = source_turf.x
 	var/Sy = source_turf.y
 
@@ -68,7 +69,24 @@
 	for (Tthing in RANGE_TURFS(Ceiling(light_range), source_turf))
 		T = Tthing
 		check_t:
-		for (thing in T.get_corners())
+
+		if (T.dynamic_lighting || T.light_sources)
+			Tcorners = T.corners
+			if (!T.lighting_corners_initialised)
+				T.lighting_corners_initialised = TRUE
+
+				if (!Tcorners)
+					T.corners = list(null, null, null, null)
+					Tcorners = T.corners
+
+				for (var/i = 1 to 4)
+					if (Tcorners[i])
+						continue
+
+					Tcorners[i] = new /datum/lighting_corner(T, LIGHTING_CORNER_DIAGONAL[i])
+
+			if (!T.has_opaque_atom)
+				for (thing in Tcorners)
 					C = thing
 					corners[C] = 0
 

code/modules/lighting/lighting_turf.dm

@@ -148,6 +148,8 @@
 		else
 			lighting_clear_overlay()
 
+// This is inlined in lighting_source.dm and lighting_source_novis.dm.
+// Update them too if you change this.
 /turf/proc/get_corners()
 	if (!dynamic_lighting && !light_sources)
 		return null
@@ -160,6 +162,8 @@
 
 	return corners
 
+// This is inlined in lighting_source.dm and lighting_source_novis.dm.
+// Update them too if you change this.
 /turf/proc/generate_missing_corners()
 	if (!dynamic_lighting && !light_sources)
 		return