Build a BVH

A BVH (Bounding Volume Hierarchy) is a spatial index that stores the bounding boxes of all instances.
It speeds up frustum culling and raycasting by discarding entire branches of the tree at once.

iMesh.computeBVH();

Tip

Build the BVH after positioning all instances. Once created, it is updated automatically when instances move (see autoUpdateBVH).

Dynamic and Static Scenes

• Static or mostly static scenes: building the BVH once is the fastest option, as culling and raycasting become much cheaper.
• Highly dynamic scenes: updating the BVH can cost more than it saves. Passing a margin makes updates faster, or the linear approach may be preferable.

Configuration

iMesh.computeBVH({
  margin: 10,                  // extra space around each box, for moving instances
  getBBoxFromBSphere: false,   // compute boxes from the geometry bounding sphere (faster, less precise)
  accurateCulling: true        // ignore the margin during frustum culling, avoiding false positives (default)
});

See BVHParams for more details.

Note

getBBoxFromBSphere requires a geometry with the bounding sphere centered at the origin.

Remove the BVH

iMesh.disposeBVH(); // back to the linear approach

Note

See the InstancedMeshBVH API for the available methods.