Drawables

In the Egloo drawing pipeline, the GlDrawable class controls what to draw. In GLES terms, each drawable contains:

its vertex array, containing the position of each vertex
its model matrix, to control scale, rotation, translation, and so on
its glDrawArrays logic, for example for using GL_TRIANGLE_FAN or GL_TRIANGLE_STRIP

Drawables are very easy to implement. We offer a few implementations:

Name	Description
`Gl2dDrawable`	Base class for 2D drawables, that have 2 coordinates per vertex.
`Gl3dDrawable`	Base class for 2D drawables, that have 3 coordinates per vertex.
`GlRect`	A 2D drawable made of four vertices. By default, it covers the entire viewport and is typically used for textures.
`GlPolygon`	A regular 2D polygon. For example: `pentagon = GlPolygon(5)`.
`GlTriangle`	A regular 2D triangle, extending `GlPolygon`.
`GlSquare`	A 2D square, extending `GlPolygon`.
`GlCircle`	A 2D circle, implemented as a `GlPolygon` with 360 sides.
`GlRoundRect`	A 2D rounded rect, with customizable corners.

Each drawable can have different methods to customize its appearance and behavior.