Wip implementation of octahedral impostors in three.js, following this great blog post on octahedral impostors in Fortnite/Unreal Engine by Ryan Brucks and the octahedron unwrapping demo by Sketchpunk Labs.
This repo mostly contributes the atlas generation and showcases a very hacky way to render the impostor at runtime, by just raycasting the original mesh to find the three nearest sprites from the triangle intersection (each vertex represents/encodes the sprite captured from that direction) and weighting them by the barycentric coordinates. The result is not pretty, but it gives an idea of what's possible!
If anyone is interested in contributing, pushing this further along, the proper runtime is what's missing. Skipping raycasts and decoding the octahedron in the shader based on view direction instead (at least I think that's what should be happening) and improving the blending based on depth. The billboard is also not quite rotated correctly (this gets explained in the blog post) which becomes especially noticeable if you look from below or above.
- OS Godot Implementation
- OS Unity Implementation
- Blending Billboards based on Depth
- Unity Impostor Solutions overview by Rune Skovbo Johansen
- Octahedral Impostors in UE/Fortnite
Scene Overview
Raycasting the original mesh to find the three closest atlas images (here 161, 162, 176):
Finding the sprites on the atlas
