133 lines
3.7 KiB
Lua
133 lines
3.7 KiB
Lua
-- Use the movement gravity for the downwards acceleration.
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-- The setting may change in-game but for simplicity we don't support this.
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local movement_gravity = tonumber(core.settings:get("movement_gravity")) or 9.81
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-- get_flow_target_raw determines position to which the water flows, or returns
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-- nothing if no target position was found
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local neighbour_offsets = {
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{x=-1, y=0, z=0},
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{x=1, y=0, z=0},
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{x=0, y=0, z=-1},
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{x=0, y=0, z=1}
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}
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local function get_flow_target_raw(pos)
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local param2 = minetest.get_node(pos).param2
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if param2 > 7 then
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-- The liquid flows downwards
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return
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end
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local neighbours = {}
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for n = 1, 4 do
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local p = vector.add(pos, neighbour_offsets[n])
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neighbours[n] = p
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neighbours[n + 4] = minetest.get_node(p)
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end
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for i = 1, 4 do
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-- If a neighbour has a lower height, flow to it
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local node = neighbours[i + 4]
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if node.name == "default:water_flowing"
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and node.param2 < param2 then
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return neighbours[i]
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end
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end
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for i = 1, 4 do
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-- Flow to a downwards-flowing neighbour if its height is not too small
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local node = neighbours[i + 4]
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if node.name == "default:water_flowing"
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and node.param2 >= 11 then
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return neighbours[i]
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end
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end
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for i = 1, 4 do
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-- Flow to a neighbouring unsolid node
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local node = neighbours[i + 4]
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if node.name ~= "default:water_flowing" then
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local def = minetest.registered_nodes[node.name]
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if def and not def.walkable then
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return neighbours[i]
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end
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end
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end
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-- No neighbour found
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end
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-- get_flow_target caches the results from get_flow_target_raw for 10 s
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local flow_target_cache = {}
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setmetatable(flow_target_cache, {__mode = "kv"})
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local function get_flow_target(pos)
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local vi = minetest.hash_node_position(pos)
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local t = minetest.get_us_time()
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if flow_target_cache[vi]
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and t - flow_target_cache[vi][1] < 10 * 1000000 then
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return flow_target_cache[vi][2]
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end
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local flow_target = get_flow_target_raw(pos)
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flow_target_cache[vi] = {t, flow_target}
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return flow_target
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end
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local item_entity = minetest.registered_entities["__builtin:item"]
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local old_on_step = item_entity.on_step
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item_entity.makes_footstep_sound = true
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-- The "bt_" prefix shows that the value comes from builtin_item
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item_entity.bt_timer = 0
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item_entity.on_step = function(self, dtime, ...)
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-- Remember the velocity before an original on_step can change it
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local vel_desired
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if self.bt_reset_velocity then
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vel_desired = self.object:get_velocity()
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end
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old_on_step(self, dtime, ...)
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-- Ignore the item if it should not interact with physics
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if not self.physical_state then
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return
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end
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-- Reset the velocity if needed
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if vel_desired
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and not vector.equals(self.object:get_velocity(), vel_desired) then
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self.object:set_velocity(vel_desired)
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end
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-- For performance reasons, skip the remaining code in frequent steps
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self.bt_timer = self.bt_timer + dtime
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if self.bt_timer < 0.1 then
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return
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end
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self.bt_timer = 0
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local p = self.object:get_pos()
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local pos = vector.round(p)
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local nodename = minetest.get_node(pos).name
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if self.bt_reset_velocity then
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-- Set the item acceleration to its default (changed again below)
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self.object:set_acceleration({x=0, y=-movement_gravity, z=0})
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self.bt_reset_velocity = nil
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end
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local def = minetest.registered_nodes[nodename]
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if not def or not def.liquidtype or def.liquidtype ~= "flowing" then
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return
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end
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local pos_next = get_flow_target(pos)
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if not pos_next then
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return
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end
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local vel_current = vel_desired or self.object:get_velocity()
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local acc = vector.multiply(vector.subtract(pos_next, pos), 2.0)
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if math.abs(vel_current.x) > 1.0 then
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acc.x = 0
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end
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if math.abs(vel_current.z) > 1.0 then
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acc.z = 0
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end
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acc.y = -movement_gravity
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self.object:set_acceleration(acc)
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self.bt_reset_velocity = true
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end
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minetest.register_entity(":__builtin:item", item_entity)
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