CPLcrossline

by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - CPL/Closed Polygon Lists
Introduced first in SolidGeometry 5.1, Creation date: 2021-12-05, Last change: 2025-09-15

calculates the intersection of a CPL with a line

See Also: crossC2P , CPLofPLcrossCPL

Example Illustration

missing image of CPLcrossline(CPL,PL,acc);

Syntax

CPLX=CPLcrossline(CPL,PL,[acc]);

Input Parameter

`CPL`:		CLosed polygon region
`PL`:		Point list
`acc`:		accuracy, line thickness; default is 0.01

Output Parameter

CPLX: Crossing Area

Examples


CPLcrossline(CPLsample(37),[0 0;0 10],1)

Copyright 2021-2025 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, CPLcrossline, calculates the intersection of a closed polygon list (CPL) with a line defined by a point list (PL). It is part of the SolidGeometry library.

Input Parameters

CPL: A closed polygon region, represented as a list of points that form a closed shape.
PL: A point list that defines a line. It is a 2D array where each row represents a point in 2D space.
acc: An optional parameter that specifies the accuracy or thickness of the line. The default value is 0.01 if not provided.

Output

CPLX: The resulting intersection area between the closed polygon and the line.

Algorithm Steps

The function begins by determining the accuracy parameter, acc, using the getfuncparams function. If acc is not provided, it defaults to 0.1.
The point list PL is converted to its real component using real(PL), ensuring it is in a suitable format for further processing.
The function PLgrowline is called with PL and acc to create a grown line, CPLB, which represents the line with a specified thickness.
The intersection of the closed polygon CPL and the grown line CPLB is calculated using the function CPLintersect, resulting in CPLX.
If no output arguments are specified (nargout==0), the function proceeds to visualize the results:

SGfigure is called to create a new figure for plotting.
CPSplot is used to plot the closed polygon CPL in green with a line thickness of 0.1.
CPSplot is used again to plot the grown line CPLB in green with a white edge.
CPSplot is used to plot the intersection area CPLX in red with a line thickness of 1.
PLplot is used to plot the original line PL in black with a line thickness of 2.
plotannotation is called to add a legend to the plot, indicating the colors and their corresponding elements.

Algorithm explaination created using ChatGPT on 2025-08-18 23:31. (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