polyNormal

Below is a demonstration of the features of the polyNormal function

Contents

clear; close all; clc;

Syntax

[varargout]=polyNormal(V_poly);

Description

UNDOCUMENTED

Examples

Plot settings

markerSize=50;
lineWidth=2;
fontSize=25;

Example 1: Getting point-wise normal vectors for a 2D polygon

x=linspace(0,2*pi,15)';
y=sin(x);
V=[x y];

Using all defaults:

N=polyNormal(V)

N =

   -0.6951    0.7190
   -0.6568    0.7541
   -0.5162    0.8564
   -0.2103    0.9776
    0.2103    0.9776
    0.5162    0.8564
    0.6568    0.7541
    0.6951    0.7190
    0.6568    0.7541
    0.5162    0.8564
    0.2103    0.9776
   -0.2103    0.9776
   -0.5162    0.8564
   -0.6568    0.7541
   -0.6951    0.7190

Example 2: Getting point-wise normal vectors for a 3D polygon

t=linspace(0,2*pi,15)';
x=cos(t);
y=sin(t);
z=2*(t./(2*pi));
V=[x y z];

Using all defaults:

N=polyNormal(V)

N =

   -0.9749   -0.2225         0
   -0.9010   -0.4339         0
   -0.6235   -0.7818         0
   -0.2225   -0.9749         0
    0.2225   -0.9749         0
    0.6235   -0.7818         0
    0.9010   -0.4339         0
    1.0000   -0.0000         0
    0.9010    0.4339         0
    0.6235    0.7818         0
    0.2225    0.9749         0
   -0.2225    0.9749         0
   -0.6235    0.7818         0
   -0.9010    0.4339         0
   -0.9749    0.2225         0

Example 3: Getting point-wise normal vectors for a non-closed polygon

Specifying options

optionStruct.closeLoopOpt=false; %Wether the input should be considered a closed curve
optionStruct.type='vertex'; % 'vertex'/'node' or 'segment'/'edge'
optionStruct.zDir=[0 1 1]; %z-direction

[N,VN]=polyNormal(V,optionStruct);

cFigure;  hold on;
hp1=plotV(V,'k.-','MarkerSize',markerSize,'LineWidth',lineWidth);
hp2=quiverVec(VN,N,0.5,'r');
legend([hp1 hp2],{'Polygon','vertex normal vectors'});
axisGeom(gca,fontSize);
drawnow;

Example 4: Getting segment-wise normal vectors for a non-closed polygon

optionStruct.closeLoopOpt=false; %Wether the input should be considered a closed curve
optionStruct.type='segment'; % 'vertex'/'node' or 'segment'/'edge'
optionStruct.zDir=[0 0 1]; %z-direction

[N,VN]=polyNormal(V,optionStruct);

cFigure;  hold on;
hp1=plotV(V,'k.-','MarkerSize',markerSize,'LineWidth',lineWidth);
hp2=quiverVec(VN,N,0.5,'b');
legend([hp1 hp2],{'Polygon','segment normal vectors'});
axis equal; grid on; box on;
set(gca,'FontSize',fontSize);
drawnow;

Example 5: Getting point-wise normal vectors for a closed polygon

t=linspace(0,2*pi,25)'; t=t(1:end-1);
r=3;
x=r*cos(t);
y=r*sin(t);
V=[x y];

optionStruct.closeLoopOpt=true; %Wether the input should be considered a closed curve
optionStruct.type='vertex'; % 'vertex'/'node' or 'segment'/'edge'
optionStruct.zDir=[0 0 1]; %z-direction

N=polyNormal(V,optionStruct);

cFigure;  hold on;
hp1=plotV(V,'k.-','MarkerSize',markerSize,'LineWidth',lineWidth);
hp2=quiverVec(V,N,1,'r');
legend([hp1 hp2],{'Polygon','segment normal vectors'});
axis equal; grid on; box on;
set(gca,'FontSize',fontSize);
drawnow;

Example 6: Getting segment-wise normal vectors for a closed polygon

optionStruct.closeLoopOpt=true; %Wether the input should be considered a closed curve
optionStruct.type='segment'; % 'vertex'/'node' or 'segment'/'edge'
optionStruct.zDir=[0 0 1]; %z-direction

[N,VN]=polyNormal(V,optionStruct);

cFigure;  hold on;
hp1=plotV(V,'k.-','MarkerSize',markerSize,'LineWidth',lineWidth);
hp2=quiverVec(VN,N,1,'b');
legend([hp1 hp2],{'Polygon','segment normal vectors'});
axis equal; grid on; box on;
set(gca,'FontSize',fontSize);
drawnow;

GIBBON www.gibboncode.org

Kevin Mattheus Moerman, [email protected]

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License: https://github.com/gibbonCode/GIBBON/blob/master/LICENSE

GIBBON: The Geometry and Image-based Bioengineering add-On. A toolbox for image segmentation, image-based modeling, meshing, and finite element analysis.

Copyright (C) 2006-2023 Kevin Mattheus Moerman and the GIBBON contributors

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

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Published with MATLAB® R2023a