VLFLofTR

by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - TR/Tetrahedrons
Introduced first in SolidGeometry 2.0, Creation date: 2014-12-22, Last change: 2025-09-14

returns the freeboundary surface of a tetrahedron or the surface of a triangulation

Description

Returns the surface model (VL,FL) from a tetrahedron volume model by using freeBoundary. If the triangulation is a surface model, the ConnectivityList is returned.

Example Illustration

Syntax

[VL,FL]=VLFLofTR(TR)

Input Parameter

TR: Triangulation (nx4 or nx3)

Output Parameter

`VL`:		Vertex List (Point List)
`FL`:		Facet List (ConnectivityList or freeBoundary)

Examples


[VL,FL]=VLFLofTR(exp_2014_12_23 (SGsample(16))); close all; VLFLfigure; view(-30,30); VLFLplots(VL,FL);

Copyright 2014-2025 Tim C. Lueth. All rights reserved. The code is the property of Tim C. Lueth and may not be redistributed or modified without explicit written permission. This software may be used free of charge for academic research and teaching purposes only. Commercial use, redistribution, modification, or reverse engineering is strictly prohibited. Access to source code is restricted and granted only under specific agreements. For licensing inquiries or commercial use, please contact: Tim C. Lueth

Algorithm (Workflow)

This function, VLFLofTR, is designed to generate the surface model from a tetrahedron volume model, which can be used for writing an STL file. It is part of the SG-Library and was created by Tim Lueth on December 22, 2014.

Input Parameters

TR: This is the triangulation input, which can be either an nx4 or nx3 matrix. It represents the connectivity of the points in the tetrahedron or triangulation.

Output Results

VL: Vertex List, which is essentially the list of points in the triangulation.
FL: Facet List, which is the connectivity list or the free boundary of the triangulation.

Algorithm Steps

Assign the points from the triangulation TR to the variable VL.
Check the size of the second dimension of TR.ConnectivityList:

If it is 4, indicating a tetrahedron, compute the free boundary using the freeBoundary function and assign it to FL.
If it is not 4, directly assign TR.ConnectivityList to FL.

If no output arguments are specified (nargout==0), perform the following:

Create a new figure using SGfigure and set the view angle to (-30, 30).
Plot the vertex and facet list using VLFLplot and set the plot light with a red color and intensity of 0.9.
Identify and plot the vertices that are not part of any facet using VLplot with a green dot marker.

Algorithm explaination created using ChatGPT on 2025-08-18 23:32. (Please note: No guarantee for the correctness of this explanation)

Last html export of this page out of FM database by TL: 2025-09-21