# patchNormal

Below is a demonstration of the features of the `patchNormal` function

## Contents

```
clear; close all; clc;
```

## Syntax

`[N,Vn,Nv]=patchNormal(F,V);`

## Description

Compute the surface normals N for the input path data defined by the faces F and vertices V. Optional additional outputs include the face centres Vn or the vertex normals Nv.

## Examples

testCase=2; switch testCase case 1 %Single element square 1x1 z=2; V=[0 0 0; 1 0 0; 0 1 z; 1 1 0]; F=[1 2 4 3]; case 2 %Sphere triangles r=1; n=2; [F,V]=geoSphere(n,r); end

[N,P,NV]=patchNormal(F,V);

Visualization

s=mean(patchEdgeLengths(F,V)); cFigure; subplot(1,2,1); title('Face normals') gpatch(F,V,'bw'); quiverVec(P,N,s,'k') axisGeom; camlight headlight; subplot(1,2,2); title('Vertex normals') gpatch(F,V,'bw'); quiverVec(V,NV,s,'k') axisGeom; 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) 2006-2021 Kevin Mattheus Moerman and the GIBBON contributors

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