SurfaceFollow.py 文件源码

def project_points(points, tri_coords):
    '''Using this to get the points off the surface
    Takes the average length of two vecs off triangles
    and applies it to the length of the normals.
    This way the normal scales with the mesh and with
    changes to the individual triangle vectors'''
    t0 = tri_coords[:, 0]
    t1 = tri_coords[:, 1]
    t2 = tri_coords[:, 2]
    tv1 = t1 - t0
    tv2 = t2 - t0
    cross = np.cross(tv1, tv2)

    # get the average length of the two vectors and apply it to the cross product
    sq = np.sqrt(np.einsum('ij,ij->i', cross, cross))
    x1 = np.einsum('ij,ij->i', tv1, tv1)
    x2 = np.einsum('ij,ij->i', tv2, tv2)
    av_root = np.sqrt((x1 + x2) / 2)
    cr_root = (cross / np.expand_dims(sq, axis=1)) * np.expand_dims(av_root, axis=1)    

    v1 = points - t0
    v1_dots = np.einsum('ij,ij->i', cr_root, v1)
    n_dots = np.einsum('ij,ij->i', cr_root, cr_root)
    scale = np.nan_to_num(v1_dots / n_dots)
    offset = cr_root * np.expand_dims(scale, axis=1)
    drop = points - offset # The drop is used by the barycentric generator as points in the triangles
    return drop, scale