[MIRROR] Actually supports alpha passed into emissive stuff [MDB IGNO…

…RE] (#197)

* Actually supports alpha passed into emissive stuff (#79117)

---------
Co-authored-by: LemonInTheDark <[email protected]>

code/__DEFINES/lighting.dm

@@ -78,14 +78,18 @@
 /// Don't block any emissives. Useful for things like, pieces of paper?
 #define EMISSIVE_BLOCK_NONE 2
 
+#define _EMISSIVE_COLOR(val) list(0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,1, val,val,val,0)
 /// The color matrix applied to all emissive overlays. Should be solely dependent on alpha and not have RGB overlap with [EM_BLOCK_COLOR].
-#define EMISSIVE_COLOR list(0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,1, 1,1,1,0)
+#define EMISSIVE_COLOR _EMISSIVE_COLOR(1)
 /// A globaly cached version of [EMISSIVE_COLOR] for quick access.
 GLOBAL_LIST_INIT(emissive_color, EMISSIVE_COLOR)
+
+#define _EM_BLOCK_COLOR(val) list(0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,val, 0,0,0,0)
 /// The color matrix applied to all emissive blockers. Should be solely dependent on alpha and not have RGB overlap with [EMISSIVE_COLOR].
-#define EM_BLOCK_COLOR list(0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,1, 0,0,0,0)
+#define EM_BLOCK_COLOR _EM_BLOCK_COLOR(1)
 /// A globaly cached version of [EM_BLOCK_COLOR] for quick access.
 GLOBAL_LIST_INIT(em_block_color, EM_BLOCK_COLOR)
+
 /// A set of appearance flags applied to all emissive and emissive blocker overlays.
 /// KEEP_APART to prevent parent hooking, KEEP_TOGETHER for children, and we reset the color and alpha of our parent so nothing gets overriden
 #define EMISSIVE_APPEARANCE_FLAGS (KEEP_APART|KEEP_TOGETHER|RESET_COLOR|RESET_ALPHA)

code/__HELPERS/lighting.dm

@@ -1,9 +1,11 @@
 /// Produces a mutable appearance glued to the [EMISSIVE_PLANE] dyed to be the [EMISSIVE_COLOR].
 /proc/emissive_appearance(icon, icon_state = "", atom/offset_spokesman, layer = FLOAT_LAYER, alpha = 255, appearance_flags = NONE, offset_const)
-	// Note: alpha doesn't "do" anything, since it's overriden by the color set shortly after
-	// Consider removing it someday? (I wonder if we made emissives blend right we could make alpha actually matter. dreams man, dreams)
 	var/mutable_appearance/appearance = mutable_appearance(icon, icon_state, layer, offset_spokesman, EMISSIVE_PLANE, 255, appearance_flags | EMISSIVE_APPEARANCE_FLAGS, offset_const)
-	appearance.color = GLOB.emissive_color
+	if(alpha == 255)
+		appearance.color = GLOB.emissive_color
+	else
+		var/alpha_ratio = alpha/255
+		appearance.color = _EMISSIVE_COLOR(alpha_ratio)
 
 	//Test to make sure emissives with broken or missing icon states are created
 	if(PERFORM_ALL_TESTS(focus_only/invalid_emissives))
@@ -15,15 +17,17 @@
 // This is a semi hot proc, so we micro it. saves maybe 150ms
 // sorry :)
 /proc/fast_emissive_blocker(atom/make_blocker)
-	// Note: alpha doesn't "do" anything, since it's overriden by the color set shortly after
-	// Consider removing it someday?
 	var/mutable_appearance/blocker = new()
 	blocker.icon = make_blocker.icon
 	blocker.icon_state = make_blocker.icon_state
 	// blocker.layer = FLOAT_LAYER // Implied, FLOAT_LAYER is default for appearances
 	blocker.appearance_flags |= make_blocker.appearance_flags | EMISSIVE_APPEARANCE_FLAGS
 	blocker.dir = make_blocker.dir
-	blocker.color = GLOB.em_block_color
+	if(make_blocker.alpha == 255)
+		blocker.color = GLOB.em_block_color
+	else
+		var/alpha_ratio = make_blocker.alpha/255
+		blocker.color = _EM_BLOCK_COLOR(alpha_ratio)
 
 	// Note, we are ok with null turfs, that's not an error condition we'll just default to 0, the error would be
 	// Not passing ANYTHING in, key difference
@@ -32,10 +36,12 @@
 
 /// Produces a mutable appearance glued to the [EMISSIVE_PLANE] dyed to be the [EM_BLOCK_COLOR].
 /proc/emissive_blocker(icon, icon_state = "", atom/offset_spokesman, layer = FLOAT_LAYER, alpha = 255, appearance_flags = NONE, offset_const)
-	// Note: alpha doesn't "do" anything, since it's overriden by the color set shortly after
-	// Consider removing it someday?
 	var/mutable_appearance/appearance = mutable_appearance(icon, icon_state, layer, offset_spokesman, EMISSIVE_PLANE, alpha, appearance_flags | EMISSIVE_APPEARANCE_FLAGS, offset_const)
-	appearance.color = GLOB.em_block_color
+	if(alpha == 255)
+		appearance.color = GLOB.em_block_color
+	else
+		var/alpha_ratio = alpha/255
+		appearance.color = _EM_BLOCK_COLOR(alpha_ratio)
 	return appearance
 
 /// Takes a non area atom and a threshold