This document describes Display Lib API. Display Lib allows to add a dynamic display on a node. Display Lib limits node rotations. For wallmounted, only vertical positionning is available, and for facedir, only first four position are availabel (those with default axis).
## Provided methods
### update\_entities
**display\_lib.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.
`on_place` node callback implementation. Display nodes should have this callback (avoid placement of horizontal display node).
### on_construct
**display\_lib.on\_construct(pos)**
`on_construct` node callback implementation. Display nodes should have this callback (creates, places and updates display entities on node construction).
`on_rotate` node callback implementation. Display nodes should have this callback (restricts rotations and rotates display entities associated with node).
`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).
- 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.
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), `height` goes from bottom (-0.5) to top (0.5) and `right` goes from left (-0.5) to right (0.5).
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.
