# Constructive Solid Geometry

CSG nodes create 3D meshes by combining primitive shapes with boolean operations.

## Primitives

```python
from simvx.core import CSGBox3D, CSGSphere3D, CSGCylinder3D, Vec3

box = CSGBox3D(size=Vec3(2, 1, 1))
sphere = CSGSphere3D(radius=1.0, rings=16, sectors=16)
cylinder = CSGCylinder3D(radius=0.5, height=2.0, segments=16)
```

| Node | Properties |
|------|-----------|
| `CSGBox3D` | `size` (Vec3, default 1,1,1) |
| `CSGSphere3D` | `radius` (1.0), `rings` (16), `sectors` (16) |
| `CSGCylinder3D` | `radius` (0.5), `height` (1.0), `segments` (16) |

## Boolean Operations

`CSGCombiner3D` combines child CSG shapes using their `operation` property:

```python
from simvx.core import CSGCombiner3D, CSGBox3D, CSGSphere3D, CSGOperation

combiner = CSGCombiner3D()

box = CSGBox3D(size=(2, 2, 2))
combiner.add_child(box)

hole = CSGSphere3D(radius=1.2)
hole.operation = CSGOperation.SUBTRACT
combiner.add_child(hole)

# Get the resulting mesh
mesh = combiner.get_mesh()
```

| Operation | Result |
|-----------|--------|
| `CSGOperation.UNION` | Merge shapes together (default) |
| `CSGOperation.SUBTRACT` | Cut the child shape from the first |
| `CSGOperation.INTERSECT` | Keep only the overlapping region |

## Rendering CSG

Attach the resulting mesh to a `MeshInstance3D` for rendering:

```python
from simvx.core import MeshInstance3D, Material

mesh_node = MeshInstance3D()
mesh_node.mesh = combiner.get_mesh()
mesh_node.material = Material(colour=(0.8, 0.3, 0.1))
self.add_child(mesh_node)
```

## API Reference

See {py:mod}`simvx.core.csg` for the complete CSG API.