Display API

This document describes Display API. Display API allows to add a dynamic display on a node. Display API limits node rotations. For wallmounted, only vertical positionning is available. For facedir, only first four position are availabel (those with default axis).

Provided methods

update_entities

display_api.update_entities(pos)

This method triggers entities update for the display node at pos. Actual entity update is made by on_display_update callback associated to the entity.

pos: Position of the node

register_display_entity

display_api.register_display_entity(entity_name)

This is a helper to register entities used for display.

entity_name: Name of the entity to register.

Provided callback implementations

on_place

display_api.on_place(itemstack, placer, pointed_thing)

on_place node callback implementation. Display nodes should have this callback (avoid placement of horizontal display node).

on_construct

display_api.on_construct(pos)

on_construct node callback implementation. Display nodes should have this callback (creates, places and updates display entities on node construction).

on_destruct

display_api.on_destruct(pos)

on_destruct node callback implementation. Display nodes should have this callback (removes display entities on node destruction).

on_rotate

display_api.on_rotate(pos, node, user, mode, new_param2)

on_rotate node callback implementation. Display nodes should have this callback (restricts rotations and rotates display entities associated with node).

on_activate

display_api.on_activate(entity, staticdata)

On_activate entity callback implementation for display entities. No need of this method if display entities have been registered using register_display_entity (callback is already set).

Howto register a display node

Register display entities with register_display_entity
Register node with :
- on_place, on_construct, on_destruct and on_rotate callbacks using display_api callbacks.\
- display_api group. This will make this node have their entities updated as soon as the mapblock is loaded (Useful after /clearobjects).\
- a display_entities field in node definition containing a entity name indexed table. See below for description of each display_entities fields.\

Display_entities fields

on_display_update is a callback in charge of setting up entity texture. If not set, entity will have no texture and will be displayed as unknown item.
depth, right and top: Entity position regarding to node facedir/wallmounted main axis.
Values for these fields can be any number between -1.5 and 1.5 (default value is 0). Position 0,0,0 is the center of the node.
depth goes from front (-0.5) to rear (0.5), top goes from bottom (-0.5) to top (0.5) and right goes from left (-0.5) to right (0.5).
yaw: Entity yaw in radians, regarding to main axis. Default is 0, aligned to node face.

In order to avoid flickering text, it's better to have text a little behind node surface. A good spacing value is given by display_api.entity_spacing variable.

Example

display_api.register_display_entity("mymod:entity1")
display_api.register_display_entity("mymod:entity2")

function my_display_update1(pos, objref)
	objref:set_properties({ textures= {"mytexture1.png"},
	                        visual_size = {x=1, y=1} })
end

function my_display_update2(pos, objref)
	objref:set_properties({ textures= {"mytexture2.png"},
	                        visual_size = {x=1, y=1} })
end

minetest.register_node("mymod:test_display_node", {
	...
	paramtype2 = "facedir",
	...
	groups = { display_api = 1, ... },
	...
	display_entities = {
		["mymod:entity1"] = {
			depth = 0.3,
			on_display_update = my_display_update1 },
		["mymod:entity1"] = {
			depth = 0.2, top = 0.1,
			on_display_update = my_display_update2 },
		},
	...
	on_place = display_api.on_place,
	on_construct = display_api.on_construct,
	on_destruct = display_api.on_destruct,
	on_rotate = display_api.on_rotate,
	...
})

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