warp.mesh_get_group_root

warp.mesh_get_group_root(id: uint64, group: int32) → int

Kernel

Get the root of a group in a warp.Mesh.

Parameters:

• id – The mesh identifier

• group – The group identifier

Returns:

The root node index for the specified group. If the group does not exist, returns -1

(sentinel for the mesh’s global root). Pass -1 to mesh queries to traverse from the global root.

Example

@wp.kernel
def group1_only(mesh_id: wp.uint64, origin: wp.vec3, dir: wp.vec3, out_face: wp.array[wp.int32]):
    root = wp.mesh_get_group_root(mesh_id, 1)
    hit = wp.mesh_query_ray(mesh_id, origin, dir, 1.0e6, root)
    if hit.result:
        out_face[0] = hit.face

points = wp.array([[0,0,0],[1,0,0],[0,1,0],  [0,0,5],[1,0,5],[0,1,5]], dtype=wp.vec3)
indices = wp.array([0,1,2, 3,4,5], dtype=wp.int32)
groups = wp.array([0, 1], dtype=wp.int32)
mesh = wp.Mesh(points=points, indices=indices, groups=groups)

out_face = wp.full(1, -1, dtype=wp.int32)
wp.launch(group1_only, dim=1, inputs=[mesh.id, wp.vec3(0.1, 0.1, -1.0), wp.vec3(0.0, 0.0, 1.0)], outputs=[out_face])
print("hit face:", out_face.numpy()[0])

hit face: 1