transparency: too much overlapping

[toloudis]

Use Case

When PDB geometry is rendered, there are so many overlapping spheres that the alphas accumulate to essentially be totally opaque. They don't look transparent. This can happen with any type of geometry but PDBs are easy to see the problem.

Acceptance Criteria

I'm not sure what we want it to look like exactly but perhaps clamping alpha to some small value will be sufficient. We want roughly the frontmost faces of an agent to show transparency and hide the complexity of the possible transparent layers behind it. At least on a per agent basis but possibly globally.

Details

Let RGB blend as normal with SRC_ALPHA, 1-SRC_ALPHA, but don't blend alpha the same way. Alpha could use ONE, ZERO blending to just write the incoming alpha value.

[toloudis]

Part of acceptance criteria: show results and evaluate quality. Decide whether more work is needed.