ELofjointFL
by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - EL/Edge Lists
Introduced first in SolidGeometry 2.4, Creation date: 2015-07-31, Last change: 2025-09-14
returns a list of joint edges of two facet list
Description
efficient function that uses ismember to detect corresponding edges in facet lists. Format is:
[start vertex index, end vertex index, FL1 index, FL2 index]
used if two open sub-surfaces of a solid are linked by an border line
Example Illustration
Syntax
[ELiL]=ELofjointFL(FL1,FL2)
Input Parameter
FL1: | | Facet List 1 |
FL2: | | Facet List 2 |
Output Parameter
[ELiL]: | | Edge list plus Facet Index in FL1 and FL2 |
Copyright 2015-2025 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 algorithm identifies joint edges between two facet lists, FL1 and FL2, and returns a list of these edges along with their corresponding facet indices in both lists.
Input Parameters
- FL1: The first facet list, where each row represents a facet defined by three vertex indices.
- FL2: The second facet list, similar in structure to FL1.
Output
- ELiL: A list of joint edges, each represented by the start vertex index, end vertex index, and the indices of the facets in FL1 and FL2 that share the edge.
Algorithm Steps
- Determine the number of facets in FL1 and FL2 using
size(FL1,1) and size(FL2,1), respectively.
- Create an edge list for FL1,
EL1, by extracting edges from each facet and appending the facet index:
- Edges are extracted as pairs of vertex indices: [1 2], [2 3], and [3 1].
- Each edge is associated with its facet index from FL1.
- Create an edge list for FL2,
EL2, in a similar manner to EL1.
- Use the
ismember function to find common edges between EL1 and EL2:
- Check if each edge in
EL1 (considered as [start, end]) matches any edge in EL2 (considered as [end, start]).
- The
ismember function returns a logical array c indicating matches and an array d with indices of matching edges in EL2.
- Construct the output list
ELiL by combining the matching edges from EL1 with their corresponding facet indices from EL2.
Algorithm explaination created using ChatGPT on 2025-08-18 22:56. (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