Chapter 21. True Impostors — Eric Risser
- Source: https://developer.nvidia.com/gpugems/gpugems3/part-iv-image-effects/chapter-21-true-impostors
- Volume: GPU Gems 3
- Note: add-only excerpt; images omitted.
Summary of full chapter read
Billboard always faces camera; pixel shader ray-casts into multi-layer heightfield volume stored in RGBA (4 height layers). Not a static impostor texture — accurate for any view.
Opaque: ray march + binary search (Policarpo-style). Translucent: linear intersection per layer + refraction + accumulate distance for opacity. Intrinsic LOD (fill-rate dependent). CPU depth-sort billboards to limit overdraw. Demo: Jupiter ring with ~250k asteroids. Related to relief/parallax but unrestricted view for whole objects.