Implementation:Google deepmind Mujoco MJWarp BVH

Knowledge Sources	Google_deepmind_Mujoco MJWarp Documentation
Domains	Physics_Simulation, GPU_Computing, NVIDIA_Warp
Last Updated	2026-02-15 04:00 GMT

Overview

MJWarp BVH implements Bounding Volume Hierarchy construction and refitting for GPU-accelerated collision broadphase and rendering in MuJoCo Warp.

Description

This module provides GPU-based BVH (Bounding Volume Hierarchy) construction and dynamic refitting for scene geometry, meshes, height fields, and flex elements. It computes axis-aligned bounding boxes (AABBs) for various geometry types (box, sphere, capsule, plane, ellipsoid, cylinder) and builds hierarchical spatial acceleration structures used by the collision detection and ray-casting subsystems. The module also handles flex element BVH construction including vertex normal computation and shell/side assembly.

Usage

Called during the rendering and collision pipeline to build and refit BVH structures when geometry transforms change. The primary entry point refit_bvh is invoked each step to update the dynamic BVH in the render context.

Code Reference

Source Location

• Repository: Google_deepmind_Mujoco
• File: mjx/mujoco/mjx/third_party/mujoco_warp/_src/bvh.py
• Lines: 1-1013

Key Functions

# Primary entry point - refits dynamic BVH structures
def refit_bvh(m: Model, d: Data, rc: RenderContext)

# Scene BVH construction and refitting
def build_scene_bvh(m: Model, d: Data, rc: RenderContext)
def refit_scene_bvh(m: Model, d: Data, rc: RenderContext)

# Mesh and height field BVH
def build_mesh_bvh(...)
def build_hfield_bvh(...)

# Flex element BVH
def build_flex_bvh(...)
def refit_flex_bvh(m: Model, d: Data, rc: RenderContext)

# Warp functions for computing AABB bounds per geometry type
def _compute_box_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]
def _compute_sphere_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]
def _compute_capsule_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]
def _compute_plane_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]
def _compute_ellipsoid_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]
def _compute_cylinder_bounds(pos, rot, size) -> Tuple[wp.vec3, wp.vec3]

Import

from mujoco.mjx.third_party.mujoco_warp._src.bvh import refit_bvh
from mujoco.mjx.third_party.mujoco_warp._src.bvh import build_scene_bvh
from mujoco.mjx.third_party.mujoco_warp._src.bvh import build_mesh_bvh

I/O Contract

Inputs

Name	Type	Required	Description
m	Model	Yes	Warp model containing geometry definitions, sizes, and mesh data
d	Data	Yes	Warp simulation data with current geom positions and orientations
rc	RenderContext	Yes	Render context holding BVH arrays to be built or refitted

Outputs

Name	Type	Description
rc.scene_bvh	wp.Bvh	Updated scene-level BVH acceleration structure
rc.mesh_bvh	wp.Bvh	Per-mesh BVH for triangle-level queries
rc.flex_bvh	wp.Bvh	Flex element BVH for deformable body queries

Related Pages

• Environment:Google_deepmind_Mujoco_MJX_Warp_CUDA_Environment