client optimizations for lighting overlays

Removes lighting transitions- they don't work with the new system.
Greyscale overlays now use BLEND_OVERLAY instead of BLEND_MULTIPLY for
better client performance.
Light overlays in total darkness are now made invisible.

Signed-off-by: Mloc <colmohici@gmail.com>

code/modules/lighting/_lighting_defs.dm

@@ -3,7 +3,6 @@
 #define LIGHTING_FALLOFF 1 // type of falloff to use for lighting; 1 for circular, 2 for square
 #define LIGHTING_LAMBERTIAN 1 // use lambertian shading for light sources
 #define LIGHTING_HEIGHT 1 // height off the ground of light sources on the pseudo-z-axis, you should probably leave this alone
-#define LIGHTING_TRANSITIONS 1 // smooth, animated transitions, similar to /tg/station
 #define LIGHTING_ROUND_VALUE (1 / 128) //Value used to round lumcounts, values smaller than 1/255 don't matter (if they do, thanks sinking points), greater values will make lighting less precise, but in turn increase performance, VERY SLIGHTLY.
 
 #define LIGHTING_LAYER 10 // drawing layer for lighting overlays

code/modules/lighting/lighting_overlay.dm

@@ -8,7 +8,6 @@
 	icon_state = "light1"
 	layer = LIGHTING_LAYER
 	invisibility = INVISIBILITY_LIGHTING
-	blend_mode = BLEND_MULTIPLY
 	color = "#000000"
 
 	var/lum_r
@@ -53,32 +52,31 @@
 		lighting_update_overlays += src
 
 /atom/movable/lighting_overlay/proc/update_overlay()
-	var/mx = max(lum_r, lum_g, lum_b)
-	. = 1 // factor
-	if(mx > 1)
-		. = 1/mx
-	#if LIGHTING_TRANSITIONS == 1
-	animate(src,
-		color = rgb(lum_r * 255 * ., lum_g * 255 * ., lum_b * 255 * .),
-		LIGHTING_INTERVAL - 1
-	)
-	#else
-	color = rgb(lum_r * 255 * ., lum_g * 255 * ., lum_b * 255 * .)
-	#endif
-
 	var/turf/T = loc
 
 	if(istype(T)) //Incase we're not on a turf, pool ourselves, something happened.
-		if(color != "#000000")
-			T.luminosity = 1
-		else  //No light, set the turf's luminosity to 0 to remove it from view()
-			#if LIGHTING_TRANSITIONS == 1
-			spawn(LIGHTING_INTERVAL - 1)
+		if(lum_r == lum_g && lum_r == lum_b) //greyscale
+			blend_mode = BLEND_OVERLAY
+			if(lum_r <= 0)
+				T.luminosity = 0
+				color = "#000000"
+				alpha = 255
+			else
+				T.luminosity = 1
+				color = "#000000"
+				alpha = (1 - min(lum_r, 1)) * 255
+		else
+			alpha = 255
+			var/mx = max(lum_r, lum_g, lum_b)
+			. = 1 // factor
+			if(mx > 1)
+				. = 1/mx
+			blend_mode = BLEND_MULTIPLY
+			color = rgb(lum_r * 255 * ., lum_g * 255 * ., lum_b * 255 * .)
+			if(color != "#000000")
+				T.luminosity = 1
+			else  //No light, set the turf's luminosity to 0 to remove it from view()
 				T.luminosity = 0
-			#else
-			T.luminosity = 0
-			#endif
-
 	else
 		warning("A lighting overlay realised its loc was NOT a turf (actual loc: [loc][loc ? ", " + loc.type : ""]) in update_overlay() and got pooled!")
 		qdel(src)

code/modules/lighting/~lighting_undefs.dm

@@ -3,7 +3,6 @@
 #undef LIGHTING_FALLOFF
 #undef LIGHTING_LAMBERTIAN
 #undef LIGHTING_HEIGHT
-#undef LIGHTING_TRANSITIONS
 
 #undef LIGHTING_RESOLUTION
 #undef LIGHTING_LAYER