Mesh

This module contains functions for transforming meshes and inertia matrices.

transform_inertia_matrix(inertia_matrix, rotation)

Transform an inertia matrix

Parameters:

Name	Type	Description	Default
inertia_matrix	matrix	Inertia matrix to use for transformation	required
rotation	matrix	Rotation matrix to apply to the inertia matrix	required

Returns:

Type	Description
matrix	Transformed inertia matrix

Source code in onshape_robotics_toolkit\mesh.py

def transform_inertia_matrix(inertia_matrix: np.matrix, rotation: np.matrix) -> np.matrix:
    """
    Transform an inertia matrix

    Args:
        inertia_matrix: Inertia matrix to use for transformation
        rotation: Rotation matrix to apply to the inertia matrix

    Returns:
        Transformed inertia matrix
    """

    return rotation @ inertia_matrix @ rotation.T

transform_mesh(mesh, transform)

Apply a transformation matrix to an STL mesh.

Parameters:

Name	Type	Description	Default
mesh	Mesh	STL mesh to use for transformation	required
transform	ndarray	Transformation matrix to apply to the mesh	required

Returns:

Type	Description
Mesh	Transformed STL mesh

Examples:

>>> mesh = Mesh.from_file("mesh.stl")
>>> transform = np.eye(4)
>>> transform_mesh(mesh, transform)

Source code in onshape_robotics_toolkit\mesh.py

def transform_mesh(mesh: Mesh, transform: np.ndarray) -> Mesh:
    """
    Apply a transformation matrix to an STL mesh.

    Args:
        mesh: STL mesh to use for transformation
        transform: Transformation matrix to apply to the mesh

    Returns:
        Transformed STL mesh

    Examples:
        >>> mesh = Mesh.from_file("mesh.stl")
        >>> transform = np.eye(4)
        >>> transform_mesh(mesh, transform)
    """

    _transform_vectors = partial(
        transform_vectors, rotation=transform[:3, :3], translation=transform[0:3, 3:4].T.tolist()
    )

    mesh.v0 = _transform_vectors(mesh.v0)
    mesh.v1 = _transform_vectors(mesh.v1)
    mesh.v2 = _transform_vectors(mesh.v2)
    mesh.normals = _transform_vectors(mesh.normals)

    return mesh

transform_vectors(vectors, rotation, translation)

Apply a transformation matrix to a set of vectors.

Parameters:

Name	Type	Description	Default
vectors	ndarray	Array of vectors to use for transformation	required
rotation	ndarray	Rotation matrix to apply to the vectors	required
translation	ndarray	Translation matrix to apply to the vectors	required

Returns:

Type	Description
ndarray	Array of transformed vectors

Source code in onshape_robotics_toolkit\mesh.py

def transform_vectors(vectors: np.ndarray, rotation: np.ndarray, translation: np.ndarray) -> np.ndarray:
    """
    Apply a transformation matrix to a set of vectors.

    Args:
        vectors: Array of vectors to use for transformation
        rotation: Rotation matrix to apply to the vectors
        translation: Translation matrix to apply to the vectors

    Returns:
        Array of transformed vectors
    """

    return np.dot(vectors, rotation.T) + translation * len(vectors)