patchNormalFix

Below is a demonstration of the patchNormalFix function

Contents

Syntax

[F]=patchNormalFix(F);

Description

This function reorients all faces coherently such that the face normals point in a coherent fashion.

Examples

clear; close all; clc;

Plot settings

fig_color='w'; fig_colordef='white';
fontSize=15;
faceColor='b';
faceAlpha=1;
edgeColor='k';
edgeWidth=1;

Example 1: Fix face normals using patchNormalFix

Create example geometry with incoherent face normals

%An example surface
% [F,V]=stanford_bunny('g');
[F,V]=geoSphere(2,1);

% [F,V]=tri2quad(F,V); %Conver to quadrilaterals for testing

%Alter face orientations
VF=patchCentre(F,V);
logicFlip=VF(:,1)>0 | VF(:,3)>0;
F(logicFlip,:)=fliplr(F(logicFlip,:));
F=fliplr(F);

Fix face normals using patchNormalFix

[F_fix,L]=patchNormalFix(F);

Visualisation

cFigure;
subplot(1,2,1); hold on;
title('Incoherent faces','FontSize',fontSize);
gpatch(F,V,'g');
gpatch(F(1,:),V,'none','r',1,3);
patchNormPlot(F,V);
axisGeom(gca,fontSize);
camlight('headlight');

subplot(1,2,2); hold on;
title('Coherent faces','FontSize',fontSize);
gpatch(F_fix,V,L);
patchNormPlot(F_fix,V);
axisGeom(gca,fontSize);
colormap(gjet(2)); icolorbar;
camlight('headlight');

drawnow;

Example 2: Control face orientation by providing a proper face

indStart=250; %Index of face with correct orientation
[F_fix,L]=patchNormalFix(F,indStart);

Visualisation

cFigure;
subplot(1,2,1); hold on;
title('Incoherent faces','FontSize',fontSize);
gpatch(F,V,'g');
gpatch(F(indStart,:),V,'none','r',1,3);
patchNormPlot(F,V);
axisGeom(gca,fontSize);
camlight('headlight');

subplot(1,2,2); hold on;
title('Coherent faces','FontSize',fontSize);
gpatch(F_fix,V,L);
patchNormPlot(F_fix,V);
axisGeom(gca,fontSize);
colormap(gjet(2)); icolorbar;
camlight('headlight');

drawnow;

Example 3: Control face orientation by providing a proper face

logicStart=~logicFlip;
[F_fix,L]=patchNormalFix(F,logicStart);

Visualisation

cFigure;
subplot(1,2,1); hold on;
title('Incoherent faces','FontSize',fontSize);
gpatch(F,V,'g');
gpatch(F(logicStart,:),V,'none','r',1,3);
patchNormPlot(F,V);
axisGeom(gca,fontSize);
camlight('headlight');

subplot(1,2,2); hold on;
title('Coherent faces','FontSize',fontSize);
gpatch(F_fix,V,L);
patchNormPlot(F_fix,V);
axisGeom(gca,fontSize);
colormap(gjet(2)); icolorbar;
camlight('headlight');

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