Shader to create an offset, inward-growing stroke?

[EliasHasle]

@prisoner849

Simple setting of transparent to true (no alphaTest parameter) gives an odd looking result, as further points can overlap close points. To solve this issue, we need to sort particles by distance from the camera. I found a realization of this algorithm in this example https://threejs.org/examples/?q=points#webgl_custom_attributes_points2 and applied it to my points.

Sorting points like that at every animation step is not sustainable/scalable. Hm. I still don’t understand why it is necessary. I am encountering the same problem with my spheres, when I try to set opacity on them instead of discarding fragments (eventually to achieve antialiasing). It is as if points forcibly write the clear color on top of other points.