Asteroid Shader

Shape Generation

The shape is generated with vertex displacement according to procedural 3D noise. The shader is built for a sphere mesh, whose vertices are displaced along their normal direction to create the rocky asteroid shape. 4 custom icosphere meshes of progressively increasing quality are used for this, but the default Unity sphere mesh works as well. These are used in the custom LOD system by default.

A unique ID is generated for each asteroid instance and used as a seed for the noise function, allowing for unique shapes across multiple instances while still using a single material with GPU instancing for performance. The custom per-asteroid ID system is currently based on the asteroid's unique radius within the ring, so moving an asteroid around in the scene will change its shape. This is a workaround to enable frustum culling and LOD buckets to maintain consistent shapes across draw calls as we can't use the instance ID, which would change.

Texture Baking

You can bake asteroid textures for increased performance.