convert.py 文件源码

def extrusion_to_matrix(entity):
    """
    Converts an extrusion vector to a rotation matrix that denotes the transformation between world coordinate system
    and the entity's own coordinate system (described by the extrusion vector).
    """
    def arbitrary_x_axis(extrusion_normal):
        world_y = Vector((0, 1, 0))
        world_z = Vector((0, 0, 1))
        if abs(extrusion_normal[0]) < 1 / 64 and abs(extrusion_normal[1]) < 1 / 64:
            a_x = world_y.cross(extrusion_normal)
        else:
            a_x = world_z.cross(extrusion_normal)
        a_x.normalize()
        return a_x, extrusion_normal.cross(a_x)

    az = Vector(entity.extrusion)
    ax, ay = arbitrary_x_axis(az)
    return Matrix((ax, ay, az)).inverted()