Geometry Constructors and Extractors

Added in version 5.0.

construct module provides functions for constructing and extracting parametric shapes. A surface can be constructed from curves and a volume can be constructed from surfaces. Moreover, a surface can be extracted to curves and a volume can be extracted to surfaces in all parametric directions.

Function Reference

geomdl.construct.construct_surface(direction, *args, **kwargs)

Generates surfaces from curves.

Arguments:

  • args: a list of curve instances

Keyword Arguments (optional):

  • degree: degree of the 2nd parametric direction

  • knotvector: knot vector of the 2nd parametric direction

  • rational: flag to generate rational surfaces

Parameters:

direction (str) – the direction that the input curves lies, i.e. u or v

Returns:

Surface constructed from the curves on the given parametric direction

geomdl.construct.construct_volume(direction, *args, **kwargs)

Generates volumes from surfaces.

Arguments:

  • args: a list of surface instances

Keyword Arguments (optional):

  • degree: degree of the 3rd parametric direction

  • knotvector: knot vector of the 3rd parametric direction

  • rational: flag to generate rational volumes

Parameters:

direction (str) – the direction that the input surfaces lies, i.e. u, v, w

Returns:

Volume constructed from the surfaces on the given parametric direction

geomdl.construct.extract_curves(psurf, **kwargs)

Extracts curves from a surface.

The return value is a dict object containing the following keys:

  • u: the curves which generate u-direction (or which lie on the v-direction)

  • v: the curves which generate v-direction (or which lie on the u-direction)

As an example; if a curve lies on the u-direction, then its knotvector is equal to surface’s knotvector on the v-direction and vice versa.

The curve extraction process can be controlled via extract_u and extract_v boolean keyword arguments.

Parameters:

psurf (abstract.Surface) – input surface

Returns:

extracted curves

Return type:

dict

geomdl.construct.extract_isosurface(pvol)

Extracts the largest isosurface from a volume.

The following example illustrates one of the usage scenarios:

 1from geomdl import construct, multi
 2from geomdl.visualization import VisMPL
 3
 4# Assuming that "myvol" variable stores your spline volume information
 5isosrf = construct.extract_isosurface(myvol)
 6
 7# Create a surface container to store extracted isosurface
 8msurf = multi.SurfaceContainer(isosrf)
 9
10# Set visualization components
11msurf.vis = VisMPL.VisSurface(VisMPL.VisConfig(ctrlpts=False))
12
13# Render isosurface
14msurf.render()
Parameters:

pvol (abstract.Volume) – input volume

Returns:

isosurface (as a tuple of surfaces)

Return type:

tuple

geomdl.construct.extract_surfaces(pvol)

Extracts surfaces from a volume.

Parameters:

pvol (abstract.Volume) – input volume

Returns:

extracted surface

Return type:

dict