Make mobs respect liquid/climbable physics if dead

mods/rp_mobs_mobs/land_roam.lua

@@ -1,6 +1,7 @@
 -- Behavior functions for land animals
 
 local DEATH_DRAG = 0.05
+local DEATH_DRAG_LIQUID = 0.2
 
 local random_yaw = function()
 	return math.random(0, 360) / 360 * (math.pi*2)
@@ -282,9 +283,38 @@ rp_mobs_mobs.task_queues.land_roam = function(settings)
 	return tq
 end
 
--- Default mob physics for dying
-rp_mobs_mobs.land_roamer_dying_step = function(self, dtime)
-	-- Make mob come to a halt horizontally
-	rp_mobs.drag(self, dtime, vector.new(DEATH_DRAG, 0, DEATH_DRAG), {"x", "z"})
+-- Returns a default dying_step functionn for `rp_mobs.handle_dying`.
+-- If enabled, this can toggle gravity in liquids climbable nodes,
+-- and put the mob smoothly to a halt using drag.
+-- This assumes that `rp_mobs.scan_environment` is used.
+-- Parameters:
+-- * `can_swim`: turn off gravity in swimmable nodes
+-- * `can_climb`: turn off gravity in climbable nodes
+rp_mobs_mobs.get_dying_step = function(can_swim, can_climb)
+	return function(mob, dtime)
+		if not mob._env_node then
+			return
+		end
+		local drag, drag_axes
+		local grav = mob._temp_custom_state.dying_gravity == true
+		if (can_swim and (rp_mobs_mobs.is_liquid(mob._env_node.name) or rp_mobs_mobs.is_liquid(mob._env_node_floor.name)))
+				or (can_climb and (rp_mobs_mobs.is_climbable(mob._env_node.name) or rp_mobs_mobs.is_climbable(mob._env_node_floor.name))) then
+			-- Make mob come to a halt horizontally and vertically
+			drag = vector.new(DEATH_DRAG, DEATH_DRAG_LIQUID, DEATH_DRAG)
+			drag_axes = { "x", "y", "z" }
+			if grav then
+				mob.object:set_acceleration(vector.zero())
+				mob._temp_custom_state.dying_gravity = false
+			end
+		else
+			-- Make mob come to a halt horizontally
+			drag = vector.new(DEATH_DRAG, 0, DEATH_DRAG)
+			drag_axes = { "x", "z" }
+			if not grav then
+				mob.object:set_acceleration(rp_mobs.GRAVITY_VECTOR)
+				mob._temp_custom_state.dying_gravity = true
+			end
+		end
+		rp_mobs.drag(mob, dtime, drag, drag_axes)
+	end
 end
-

mods/rp_mobs_mobs/mobs/boar.lua

@@ -101,7 +101,7 @@ rp_mobs.register_mob("rp_mobs_mobs:boar", {
 		end,
 		get_staticdata = rp_mobs.get_staticdata_default,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, false))
 			rp_mobs.scan_environment(self, dtime, -0.3)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/mobs/mineturtle.lua

@@ -207,7 +207,7 @@ rp_mobs.register_mob("rp_mobs_mobs:mineturtle", {
 		end,
 		get_staticdata = rp_mobs.get_staticdata_default,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, false))
 			rp_mobs.scan_environment(self, dtime, -0.3)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/mobs/sheep.lua

@@ -220,7 +220,7 @@ rp_mobs.register_mob("rp_mobs_mobs:sheep", {
 		end,
 		get_staticdata = rp_mobs.get_staticdata_default,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, false))
 			rp_mobs.scan_environment(self, dtime, -0.3)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/mobs/skunk.lua

@@ -90,7 +90,7 @@ rp_mobs.register_mob("rp_mobs_mobs:skunk", {
 		end,
 		get_staticdata = rp_mobs.get_staticdata_default,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, false))
 			rp_mobs.scan_environment(self, dtime, -0.1)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/mobs/villager.lua

@@ -1362,7 +1362,7 @@ rp_mobs.register_mob("rp_mobs_mobs:villager", {
 			rp_mobs.add_task_queue(self, find_sites_task_queue)
 		end,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, true))
 			rp_mobs.scan_environment(self, dtime)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/mobs/walker.lua

@@ -96,7 +96,7 @@ rp_mobs.register_mob("rp_mobs_mobs:walker", {
 		end,
 		get_staticdata = rp_mobs.get_staticdata_default,
 		on_step = function(self, dtime, moveresult)
-			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.land_roamer_dying_step)
+			rp_mobs.handle_dying(self, dtime, moveresult, rp_mobs_mobs.get_dying_step(true, false))
 			rp_mobs.scan_environment(self, dtime, -0.5)
 			rp_mobs.handle_environment_damage(self, dtime, moveresult)
 			rp_mobs.handle_tasks(self, dtime, moveresult)

mods/rp_mobs_mobs/shared.lua

@@ -25,6 +25,12 @@ rp_mobs_mobs.is_walkable = function(nodename)
 	return ndef and ndef.walkable
 end
 
+-- Returns true if node is climbable
+rp_mobs_mobs.is_climbable = function(nodename)
+	local ndef = minetest.registered_nodes[nodename]
+	return ndef and ndef.climbable
+end
+
 -- Returns true if the node(s) in front of the mob are safe.
 -- This is considered unsafe:
 -- * damage_per_second > 0