Pixel projectile ricochets and reflections! (#1220)

code/__DEFINES/flags.dm

@@ -14,6 +14,7 @@ GLOBAL_LIST_INIT(bitflags, list(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 204
 #define NOBLUDGEON		4		// when an item has this it produces no "X has been hit by Y with Z" message in the default attackby()
 #define MASKINTERNALS	8		// mask allows internals
 #define HEAR 			16		// This flag is what recursive_hear_check() uses to determine wether to add an item to the hearer list or not.
+#define CHECK_RICOCHET	32		// Projectiels will check ricochet on things impacted that have this.
 #define CONDUCT			64		// conducts electricity (metal etc.)
 #define ABSTRACT    	128		// for all things that are technically items but used for various different stuff, made it 128 because it could conflict with other flags other way
 #define NODECONSTRUCT  	128		// For machines and structures that should not break into parts, eg, holodeck stuff
@@ -57,6 +58,7 @@ GLOBAL_LIST_INIT(bitflags, list(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 204
 #define UNUSED_TRANSIT_TURF 2
 #define CAN_BE_DIRTY 4 //If a turf can be made dirty at roundstart. This is also used in areas.
 #define NO_DEATHRATTLE 16 // Do not notify deadchat about any deaths that occur on this turf.
+//#define CHECK_RICOCHET	32		//Same thing as atom flag.
 
 /*
 	These defines are used specifically with the atom/pass_flags bitmask

code/__HELPERS/maths.dm

@@ -130,6 +130,22 @@ GLOBAL_LIST_INIT(sqrtTable, list(1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4,
 	var/t = round((val - min) / d)
 	return val - (t * d)
 
+#define NORM_ROT(rot) ((((rot % 360) + (rot - round(rot, 1))) > 0) ? ((rot % 360) + (rot - round(rot, 1))) : (((rot % 360) + (rot - round(rot, 1))) + 360))
+
+/proc/get_angle_of_incidence(face_angle, angle_in, auto_normalize = TRUE)
+
+	var/angle_in_s = NORM_ROT(angle_in)
+	var/face_angle_s = NORM_ROT(face_angle)
+	var/incidence = face_angle_s - angle_in_s
+	var/incidence_s = incidence
+	while(incidence_s < -90)
+		incidence_s += 180
+	while(incidence_s > 90)
+		incidence_s -= 180
+	if(auto_normalize)
+		return incidence_s
+	else
+		return incidence
 
 //A logarithm that converts an integer to a number scaled between 0 and 1 (can be tweaked to be higher).
 //Currently, this is used for hydroponics-produce sprite transforming, but could be useful for other transform functions.
@@ -141,8 +157,6 @@ GLOBAL_LIST_INIT(sqrtTable, list(1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4,
 		return size_factor + scaling_modifier //scale mod of 0 results in a number from 0 to 1. A scale modifier of +0.5 returns 0.5 to 1.5
 		//to_chat(world, "Transform multiplier of [src] is [size_factor + scaling_modifer]")
 
-
-
 //converts a uniform distributed random number into a normal distributed one
 //since this method produces two random numbers, one is saved for subsequent calls
 //(making the cost negligble for every second call)

code/game/atoms.dm

@@ -104,6 +104,9 @@
 
 	return ..()
 
+/atom/proc/handle_ricochet(obj/item/projectile/P)
+	return
+
 /atom/proc/CanPass(atom/movable/mover, turf/target, height=1.5)
 	return (!density || !height)
 

code/game/turfs/closed.dm

@@ -24,9 +24,6 @@
 /turf/closed/indestructible/oldshuttle/corner
 	icon_state = "corner"
 
-
-
-
 /turf/closed/indestructible/splashscreen
 	name = "Space Station 13"
 	icon = 'config/title_screens/images/blank.png'

code/game/turfs/simulated/wall/mineral_walls.dm

@@ -175,6 +175,7 @@
 	desc = "A light-weight titanium wall used in shuttles."
 	icon = 'icons/turf/walls/shuttle_wall.dmi'
 	icon_state = "map-shuttle"
+	flags = CAN_BE_DIRTY | CHECK_RICOCHET
 	sheet_type = /obj/item/stack/sheet/mineral/titanium
 	smooth = SMOOTH_MORE|SMOOTH_DIAGONAL
 	canSmoothWith = list(/turf/closed/wall/mineral/titanium, /obj/machinery/door/airlock/shuttle, /obj/machinery/door/airlock/, /turf/closed/wall/shuttle, /obj/structure/window/shuttle, /obj/structure/shuttle/engine/heater, /obj/structure/falsewall/titanium)

code/game/turfs/simulated/walls.dm

@@ -28,6 +28,20 @@
 /turf/closed/wall/attack_tk()
 	return
 
+/turf/closed/wall/handle_ricochet(obj/item/projectile/P)			//A huge pile of shitcode!
+	var/turf/p_turf = get_turf(P)
+	var/face_direction = get_dir(src, p_turf)
+	var/face_angle = dir2angle(face_direction)
+	var/incidence_s = get_angle_of_incidence(face_angle, P.Angle)
+	var/new_angle = face_angle + incidence_s
+	var/new_angle_s = new_angle
+	while(new_angle_s > 180)	// Translate to regular projectile degrees
+		new_angle_s -= 360
+	while(new_angle_s < -180)
+		new_angle_s += 360
+	P.Angle = new_angle_s
+	return TRUE
+
 /turf/closed/wall/proc/dismantle_wall(devastated=0, explode=0)
 	if(devastated)
 		devastate_wall()

code/modules/projectiles/projectile.dm

@@ -28,6 +28,9 @@
 	var/spread = 0			//amount (in degrees) of projectile spread
 	var/legacy = 0			//legacy projectile system
 	animate_movement = 0	//Use SLIDE_STEPS in conjunction with legacy
+	var/ricochets = 0
+	var/ricochets_max = 2
+	var/ricochet_chance = 30
 
 	var/damage = 10
 	var/damage_type = BRUTE //BRUTE, BURN, TOX, OXY, CLONE are the only things that should be in here
@@ -132,7 +135,11 @@
 /obj/item/projectile/Bump(atom/A, yes)
 	if(!yes) //prevents double bumps.
 		return
-	if(firer)
+	if(check_ricochet() && check_ricochet_flag(A) && ricochets < ricochets_max)
+		ricochets++
+		if(A.handle_ricochet(src))
+			return FALSE
+	if(firer && !ricochets)
 		if(A == firer || (A == firer.loc && istype(A, /obj/mecha))) //cannot shoot yourself or your mech
 			loc = A.loc
 			return 0
@@ -166,6 +173,16 @@
 				picked_mob.bullet_act(src, def_zone)
 	qdel(src)
 
+/obj/item/projectile/proc/check_ricochet()
+	if(prob(ricochet_chance))
+		return TRUE
+	return FALSE
+
+/obj/item/projectile/proc/check_ricochet_flag(atom/A)
+	if(A.flags & CHECK_RICOCHET)
+		return TRUE
+	return FALSE
+
 /obj/item/projectile/Process_Spacemove(var/movement_dir = 0)
 	return 1 //Bullets don't drift in space
 

code/modules/projectiles/projectile/beams.dm

@@ -11,7 +11,9 @@
 	eyeblur = 2
 	impact_effect_type = /obj/effect/temp_visual/impact_effect/red_laser
 	light_color = LIGHT_COLOR_RED
-
+	ricochets_max = 50	//Honk!
+	ricochet_chance = 80
+
 /obj/item/projectile/beam/laser
 
 /obj/item/projectile/beam/laser/heavylaser