procedural_asteroid

attempt to generate asteroid using Urho3D

Sample images

UV mapping

Triplanar mapping

Approach:

Mesh:

1. Generate a subdivided cube or sphere mesh in 1x1x1 bounding box
2. Random scale the mesh
3. Cut the mesh by random planes. Cut means project the vertices behind the plane onto the plane.
4. Displace vertices along normal by noise.

For texturing, there are 2 ways:

1. UV mapping (drawback: there will be seams)
   1. Cut the mesh to two half, use auto_uv_map to generate UV.
   2. Use Urho3D built-in function GenerateTangents() to generate tangent.
2. Triplanar mapping (drawback: the bumpness is not as clear as method 1)
   1. Modify LitSolid shader to LitSolidTriplanar by referencing internet articles.

Normal map:

1. Generate height map by placing some random craters and white noise.
2. Port NormalMap-Online shader to c++ to generate normal map from height map.

used/referenced resources:

Used code and textures remain their own license

auto_uv_map(Eigen) for uv mapping generated mesh

FastNoise for noise

NormalMap-Online for generate normal map from height map

spheres for sphere mesh

www.textures.com for some diffuse textures

Normal Mapping for a Triplanar Shader for normal map of triplanar mapping