View page source

warp.mesh_eval_face_normal#

warp.mesh_eval_face_normal(id: uint64, face: int32) → vec3f#

  • Kernel

Evaluate the unit normal of a face of the warp.Mesh.

Returns the face’s geometric normal, normalize(cross(v1 - v0, v2 - v0)) for the face’s vertices v0, v1, v2, in the mesh’s local space. Orientation follows the face’s winding order.

Parameters:

  • id – The mesh identifier

  • face – The face (triangle) index

Returns:

The unit-length face normal, in the mesh’s local space.

Example

@wp.kernel
def face0_normal(mesh_id: wp.uint64, out: wp.array[wp.vec3]):
    out[0] = wp.mesh_eval_face_normal(mesh_id, 0)

points = wp.array([[0,0,0],[1,0,0],[1,1,0],[0,1,0],[0,0,1],[1,0,1],[1,1,1],[0,1,1]], dtype=wp.vec3)
indices = wp.array([0,3,2, 0,2,1,  4,5,6, 4,6,7,  0,1,5, 0,5,4,
                    2,3,7, 2,7,6,  0,4,7, 0,7,3,  1,2,6, 1,6,5], dtype=wp.int32)
mesh = wp.Mesh(points=points, indices=indices)

out = wp.zeros(1, dtype=wp.vec3)
wp.launch(face0_normal, dim=1, inputs=[mesh.id], outputs=[out])
print(out.numpy()[0])

[ 0.  0. -1.]