# Core API Reference

The `core module`, with the signature [`Model`](/docs/api-reference/core/model.md) class, represent a set of fairly traditional 3D library classes on a slightly higher abstraction level than the WebGL2 API, that can serve as the basic building blocks for most applications.

Also contains a limited scene graph system that provides primitive hierarchy of 3D objects with positioning, grouping, traversal and scene support.

Note that the `Model` class is in many ways the quintessential luma.gl class. It ties together many concepts in luma.gl and is a good place to start reading if you are new to the framework.


## Classes

The core module provides the following classes

* [`AnimationLoop`](/docs/api-reference/core/animation-loop.md) - render loop / app life cycle support
* [`Model`](/docs/api-reference/core/model.md) - A renderable object with attributes and uniforms.
* [`Geometry`](/docs/api-reference/core/geometry.md) - Holds attributes and drawType for a geometric primitive

## Methods

### encodePickingColor

Encodes an index as a `Uint8Array([r, g, b])` format picking color

`encodePickingColor(index)`

* `index` - index to be decoded
returns the decoded color


### decodePickingColor

Decodes a picking color in `[r, g, b]` format to an index

 * @param {Uint8Array} color - color array to be decoded
 * @return {Array} - the decoded picking color


### getNullPickingColor

Returns the picking color that doesn't match any subfeature. Use if some graphics do not belong to any pickable subfeature.


### pickModels