An agent exists in 2D or 3D space. Up to this point an agent has been represented in 2D simulations as:
A a triangle.
The point of the triangle indicated which way an agent is facing.
Agents could be different colors.
If an agent is selected by the user then it's color changed to indicate it is currently the focus.
In 3D space an agent needs to be represented somehow.
Requirements
An agent is associated with a 3D model.
The 3D model is defined in an external file (OBJ, glTF, etc).
An agent can have a variety of animations associated with it. The animations play when certain conditions are met (e.g. walking, running, jumping, etc).
Summary
An agent exists in 2D or 3D space. Up to this point an agent has been represented in 2D simulations as:
In 3D space an agent needs to be represented somehow.
Requirements