1 files changed, 240 insertions, 0 deletions
diff --git a/display_api/init.lua b/display_api/init.lua
new file mode 100644
index 0000000..bf95ded
--- /dev/null
+++ b/display_api/init.lua
@@ -0,0 +1,240 @@
+--[[
+    display_api mod for Minetest - Library to add dynamic display
+    capabilities to nodes
+    (c) Pierre-Yves Rollo
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+--]]
+
+display_api = {}
+
+-- Prefered gap between node and entity
+-- Entity positionment is up to mods but it is a good practice to use this
+-- variable as spacing between entity and node
+display_api.entity_spacing = 0.002
+
+-- Maximum entity position relative to the node pos
+local max_entity_pos = 1.5
+
+-- Miscelaneous values depending on wallmounted param2
+local wallmounted_values = {
+	[2]={dx=-1, dz=0,  rx=0,  rz=-1, yaw=-math.pi/2},
+	[3]={dx=1,  dz=0,  rx=0,  rz=1,  yaw=math.pi/2 },
+	[4]={dx=0,  dz=-1, rx=1,  rz=0,  yaw=0         },
+	[5]={dx=0,  dz=1,  rx=-1, rz=0,  yaw=math.pi   }
+}
+
+-- Miscelaneous values depending on facedir param2
+local facedir_values = {
+	[0]={dx=0,  dz=-1, rx=1,  rz=0,  yaw=0         },
+	[1]={dx=-1, dz=0,  rx=0,  rz=-1, yaw=-math.pi/2},
+	[2]={dx=0,  dz=1,  rx=-1, rz=0,  yaw=math.pi   },
+	[3]={dx=1,  dz=0,  rx=0,  rz=1,  yaw=math.pi/2 }
+}
+
+-- dx/dy = depth vector, rx/ly = right vector, yaw = yaw of entity,
+local function get_values(node)
+	local ndef = minetest.registered_nodes[node.name]
+
+	if ndef then
+		local paramtype2 = ndef.paramtype2
+		if paramtype2 == "wallmounted" or paramtype2 == "colorwallmounted" then
+			return wallmounted_values[node.param2 % 8]
+		elseif paramtype2 == "facedir" or paramtype2 == "colorfacedir"  then
+			return facedir_values[node.param2 % 32]
+		end
+	end
+end
+
+--- Gets the display entities attached with a node. Removes extra ones
+local function get_entities(pos)
+	local objrefs = {}
+	local ndef = minetest.registered_nodes[minetest.get_node(pos).name]
+	if ndef and ndef.display_entities then
+		for _, objref in
+			ipairs(minetest.get_objects_inside_radius(pos, max_entity_pos)) do
+			local entity = objref:get_luaentity()
+			if entity and ndef.display_entities[entity.name] and
+			   entity.nodepos and vector.equals(pos, entity.nodepos) then
+				if objrefs[entity.name] then
+					objref:remove() -- Remove duplicates
+				else
+					objrefs[entity.name] = objref
+				end
+			end
+		end
+	end
+	return objrefs
+end
+
+local function clip_pos_prop(posprop)
+	if posprop then
+		return math.max(-max_entity_pos, math.min(max_entity_pos, posprop))
+	else
+		return 0
+	end
+end
+
+--- (Create and) place display entities according to the node orientation
+local function place_entities(pos)
+	local node = minetest.get_node(pos)
+	local ndef = minetest.registered_nodes[node.name]
+	local values = get_values(node)
+	local objrefs = get_entities(pos)
+
+	if values and ndef and ndef.display_entities then
+		for entity_name, props in pairs(ndef.display_entities) do
+			local depth = clip_pos_prop(props.depth)
+			local right = clip_pos_prop(props.right)
+			local top = clip_pos_prop(props.top)
+			if not objrefs[entity_name] then
+				objrefs[entity_name] = minetest.add_entity(pos, entity_name,
+					minetest.serialize({ nodepos = pos }))
+			end
+
+			objrefs[entity_name]:setpos({
+				x = pos.x - values.dx * depth + values.rx * right,
+				y = pos.y - top,
+				z = pos.z - values.dz * depth + values.rz * right})
+
+			objrefs[entity_name]:setyaw(values.yaw)
+		end
+	end
+	return objrefs
+end
+
+
+--- Entity update
+function update_entity(entity)
+	if not entity then
+		return
+	end
+	
+	if not entity.nodepos then
+		entity.object:remove() -- Remove old/buggy entity
+		return
+	end
+
+	local node = minetest.get_node(entity.nodepos)
+	local ndef = minetest.registered_nodes[node.name]
+	if ndef and ndef.display_entities and
+	   ndef.display_entities[entity.name] and
+	   ndef.display_entities[entity.name].on_display_update
+	then
+		-- Call on_display_update callback of a node for one of its display entities
+		ndef.display_entities[entity.name].on_display_update(entity.nodepos,
+			entity.object)
+	end
+end
+
+--- Force entity update
+function display_api.update_entities(pos)
+	for _, objref in pairs(place_entities(pos)) do
+		update_entity(objref:get_luaentity())
+	end
+end
+
+--- On_activate callback for display_api entities. Calls on_display_update callbacks
+--- of corresponding node for each entity.
+function display_api.on_activate(entity, staticdata)
+	if entity then
+		if string.sub(staticdata, 1, string.len("return")) == "return" then
+			local data = minetest.deserialize(staticdata)
+			if data and type(data) == "table" then
+				entity.nodepos = data.nodepos
+			end
+			entity.object:set_armor_groups({immortal=1})
+		end
+		update_entity(entity)
+	end
+end
+
+--- On_place callback for display_api items.
+-- Does nothing more than preventing node from being placed on ceiling or ground
+function display_api.on_place(itemstack, placer, pointed_thing, override_param2)
+	local ndef = itemstack:get_definition()
+	local above = pointed_thing.above
+	local under = pointed_thing.under
+	local dir = {x = under.x - above.x, y = 0, z = under.z - above.z}
+
+	-- If item is not placed on a wall, use the player's view direction instead
+	if dir.x == 0 and dir.z == 0 then
+		dir = placer:get_look_dir()
+		dir.y = 0
+	end
+
+	local param2 = 0
+	if ndef then
+		local paramtype2 = ndef.paramtype2
+		if paramtype2 == "wallmounted" or paramtype2 == "colorwallmounted" then
+			param2 = minetest.dir_to_wallmounted(dir)
+		elseif paramtype2 == "facedir" or paramtype2 == "colorfacedir"  then
+			param2 = minetest.dir_to_facedir(dir)
+		end
+	end
+	return minetest.item_place(itemstack, placer, pointed_thing,
+		param2 + (override_param2 or 0))
+end
+
+--- On_construct callback for display_api items.
+-- Creates entities and update them.
+function display_api.on_construct(pos)
+	display_api.update_entities(pos)
+end
+
+--- On_destruct callback for display_api items.
+-- Removes entities.
+function display_api.on_destruct(pos)
+	for _, objref in pairs(get_entities(pos)) do
+		objref:remove()
+	end
+end
+
+-- On_rotate (screwdriver) callback for display_api items. Prevents invalid rotations and reorients entities.
+function display_api.on_rotate(pos, node, user, _, new_param2)
+	node.param2 = new_param2
+	if get_values(node) then
+		minetest.swap_node(pos, node)
+		place_entities(pos)
+		return true
+	else
+		return false
+	end
+end
+
+--- Creates display entity with some fields and the on_activate callback
+function display_api.register_display_entity(entity_name)
+	if not minetest.registered_entity then
+		minetest.register_entity(':'..entity_name, {
+			collisionbox = { 0, 0, 0, 0, 0, 0 },
+			visual = "upright_sprite",
+			textures = {},
+			on_activate = display_api.on_activate,
+			get_staticdata = function(self)
+				return minetest.serialize({ nodepos = self.nodepos })
+			end,
+		})
+	end
+end
+
+minetest.register_lbm({
+	label = "Update display_api entities",
+	name = "display_api:update_entities",
+	run_at_every_load = true,
+	nodenames = {"group:display_modpack_node", "group:display_lib_node"},
+	action = function(pos, node) display_api.update_entities(pos) end,
+})
+
+-- Compatibility
+display_lib = display_api