Demonstrate controlling transparency of agents

[blairlyons]

• Prototype transparency simularium-viewer#256
• Design for controlling transparency of agents #114

Use Case

As a user visualizing dense scenes, I would like a performant way to display objects that are transparent.

Acceptance Criteria

Development plan for implementing transparency.

Details

There are still open UX questions about when and how transparency should be controlled, i.e. does the user set it in the data and/or in real time? what are the controls like?

But first we need to figure out if transparency is feasible and how to maintain good performance in real time.