particle system troubles

[August1996]

I'm using Filament's gl_points interface to develop a particle system with parameters roughly aligned with Babylon.js' Billboard particle system, but I'm running into two problems:

1. The Billboard particle system of Babylon.js supports near-large and far-small effects, but Filament's gl_points does not support it by default. Do you have any suggestions?
2. When size is set to 1 in Babylon.js, the actual rendered particle size is 1 unit in 3D space, but gl_PointSize in Filament cannot achieve this effect. Is there any way to transform it?

@pixelflinger @prideout @bejado @romainguy