Add Sticky grenades (#677)

* Improved grenade API
* Added sticky grenade
* Improved grenade textures

mods/ctf/ctf_crafting/init.lua

@@ -279,6 +279,14 @@ crafting.register_recipe({
 	level  = 1,
 })
 
+crafting.register_recipe({
+	type   = "inv",
+	output = "grenades:frag_sticky 1",
+	items  = { "grenades:frag", "default:stick 4" },
+	always_known = true,
+	level  = 1,
+})
+
 crafting.register_recipe({
 	type   = "inv",
 	output = "grenades:smoke 1",

mods/pvp/grenades/api.md

@@ -18,6 +18,7 @@ grenades.register_grenade("name", { -- Name of the grenade (Like 'smoke' or 'fla
 	-- <obj> the grenade object
 	-- <name> the name of the player that threw the grenade
 	-- return true to cause grenade explosion
+	-- return "stop" to stop the grenade from moving
 	end,
 	clock = 3, -- Optional, controls how long until grenade detonates. Default is 3
 	particle = { -- Adds particles in the grenade's trail

mods/pvp/grenades/grenades.lua

@@ -9,7 +9,7 @@ local function remove_flora(pos, radius)
 	end
 end
 
-grenades.register_grenade("grenades:frag", {
+local fragdef = {
 	description = "Frag grenade (Kills anyone near blast)",
 	image = "grenades_frag.png",
 	on_explode = function(pos, name)
@@ -71,7 +71,16 @@ grenades.register_grenade("grenades:frag", {
 			end
 		end
 	end,
-})
+}
+
+grenades.register_grenade("grenades:frag", table.copy(fragdef))
+
+fragdef.description = "Sticky Frag grenade (Sticks to surfaces)"
+fragdef.image = "grenades_frag_sticky.png"
+fragdef.on_collide = function(obj)
+	return "stop"
+end
+grenades.register_grenade("grenades:frag_sticky", fragdef)
 
 -- Flashbang Grenade
 

mods/pvp/grenades/init.lua

@@ -34,7 +34,7 @@ function grenades.register_grenade(name, def)
 		sliding = 1,
 		particle = 0,
 		timer = 0,
-		on_step = function(self, dtime)
+		on_step = function(self, dtime, moveresult)
 			local obj = self.object
 			local vel = obj:get_velocity()
 			local pos = obj:get_pos()
@@ -48,27 +48,29 @@ function grenades.register_grenade(name, def)
 
 			-- Check for a collision on the x/y/z axis
 
-			if not vector.equals(self.last_vel, vel) and vector.distance(self.last_vel, vel) > 4 then
-				if def.on_collide and def.on_collide(obj, self.thrower_name) then
+			if moveresult.collides and moveresult.collisions then
+				if def.on_collide then
+					local c_result = def.on_collide(obj, self.thrower_name)
+
+					if c_result == true then
 						if self.thrower_name then
 							minetest.log("action", "[Grenades] A grenade thrown by " .. self.thrower_name ..
 									" explodes at " .. minetest.pos_to_string(vector.round(pos)))
 							def.on_explode(pos, self.thrower_name)
 						end
-
 						obj:remove()
+					elseif c_result == "stop" then
+						vel = vector.new()
+						self.last_vel = vector.new()
+						obj:set_velocity(vector.new())
+						obj:set_acceleration(vector.new(0, 0, 0))
+					end
 				end
 
-				if math.abs(self.last_vel.x - vel.x) > 5 then -- Check for a large reduction in velocity
-					vel.x = self.last_vel.x * -0.3 -- Invert velocity and reduce it a bit
-				end
+				if moveresult.collisions[1] and moveresult.collisions[1].axis then
+					local axis = moveresult.collisions[1].axis
 
-				if math.abs(self.last_vel.y - vel.y) > 5 then -- Check for a large reduction in velocity
-					vel.y = self.last_vel.y * -0.2 -- Invert velocity and reduce it a bit
-				end
-
-				if math.abs(self.last_vel.z - vel.z) > 5 then -- Check for a large reduction in velocity
-					vel.z = self.last_vel.z * -0.3 -- Invert velocity and reduce it a bit
+					vel[axis] = self.last_vel[axis] * -0.3
 				end
 
 				obj:set_velocity(vel)
@@ -76,27 +78,22 @@ function grenades.register_grenade(name, def)
 
 			self.last_vel = vel
 
-			if self.sliding == 1 and vel.y == 0 then -- Check if grenade is sliding
-				self.sliding = 2 -- Multiplies drag by 2
-			elseif self.sliding > 1 and vel.y ~= 0 then
-				self.sliding = 1 -- Doesn't affect drag
-			end
-
-			if self.sliding > 1 then -- Is the grenade sliding?
-				if vector.distance(vector.new(), vel) <= 1 and not vector.equals(vel, vector.new()) then -- Grenade is barely moving, make sure it stays that way
-					obj:set_velocity(vector.new())
-					obj:set_acceleration(vector.new(0, -9.8, 0))
-				end
-			else
 			norm_vel = vector.normalize(vel)
 
+			if not vector.equals(vel, vector.new()) then
 				obj:set_acceleration({
-					x = -norm_vel.x * grenades.grenade_deaccel * self.sliding,
+					x = -norm_vel.x * grenades.grenade_deaccel * (moveresult.touching_ground and 2 or 1),
 					y = -9.8,
-					z = -norm_vel.z * grenades.grenade_deaccel * self.sliding,
+					z = -norm_vel.z * grenades.grenade_deaccel * (moveresult.touching_ground and 2 or 1),
 				})
 			end
 
+			if moveresult.touching_ground then -- Is the grenade sliding?
+				if vector.distance(vector.new(), vel) <= 2 and not vector.equals(vel, vector.new()) then -- Grenade is barely moving, make sure it stays that way
+					obj:set_velocity(vector.new())
+					obj:set_acceleration(vector.new(0, -9.8, 0))
+				end
+			end
 
 			-- Grenade Particles