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# BB.Collision.Mesh (bb v0.17.0)

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Mesh loading and bounding geometry computation for collision detection.

This module provides basic mesh support for collision detection by computing bounding primitives (spheres or AABBs) from mesh vertices. Triangle-level collision detection is not supported - meshes are approximated by their bounding geometry.

Currently supports:

- Binary STL files
- ASCII STL files

## Usage

    # Load mesh and compute bounds
    {:ok, bounds} = BB.Collision.Mesh.load_bounds("/path/to/model.stl")

    # bounds contains:
    %{
      aabb: {min_vec3, max_vec3},
      bounding_sphere: {centre_vec3, radius}
    }

## Caching

Mesh bounds are cached in an ETS table to avoid repeated file parsing. The cache key includes the file path and modification time.

## Summary

### Types

bounds()

### Functions

clear_cache()

Clear the mesh bounds cache.

compute_bounds(vertices)

Compute bounding geometry from a list of vertices.

load_bounds(path)

Load mesh bounds from a file.

load_bounds!(path)

Load mesh bounds, raising on error.

## Types

# bounds()

    @type bounds() :: %{
      aabb: {BB.Math.Vec3.t(), BB.Math.Vec3.t()},
      bounding_sphere: {BB.Math.Vec3.t(), float()}
    }

## Functions

# clear_cache()

    @spec clear_cache() :: :ok

Clear the mesh bounds cache.

# compute_bounds(vertices)

    @spec compute_bounds([{float(), float(), float()}]) ::
      {:ok, bounds()} | {:error, :empty_mesh}

Compute bounding geometry from a list of vertices.

Each vertex should be a `{x, y, z}` tuple of floats.

# load_bounds(path)

    @spec load_bounds(String.t()) :: {:ok, bounds()} | {:error, term()}

Load mesh bounds from a file.

Parses the mesh file, computes bounding geometry, and caches the result. Subsequent calls with the same file (unchanged) return cached bounds.

Returns `{:ok, bounds}` or `{:error, reason}`.

# load_bounds!(path)

    @spec load_bounds!(String.t()) :: bounds()

Load mesh bounds, raising on error.