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## subtri(F,V,n,unique​Opt)

version 1.3.0.0 (7.25 KB) by
Sub-triangulates patch format data. Can be used to increase the density of triangulated data

Updated 28 Apr 2015

[Fs,Vs]=subtri(F,V,n,uniqueOpt);
Sub-triangulates the triangles defined by the patch format data F (faces) and V (vertices). Can be used to increase the density of triangulated data.

Sub-triangulates the triangles defined by the patch format data F (faces) and V (vertices). Creates n addition points on the edges of the initial triangles, thus it creates (n+1).^2 triangles per original triangle. Two methods are implemented one which iteratively splits edges and can thus only be used if log2(n+1) is a positive integer. This method guarantees that all points are unique. If log2(n+1) is not a positive integer points are seeded on all edges initially creating non-unique points. However if uniqueOpt is 1 (default if not provided) these points are suppressed using the unique command (based on rounding of coordinates to 5th decimal place after edge length based scaling).

%% EXAMPLE
[X,Y] = meshgrid(linspace(-10,10,15));
Z = sinc(sqrt((X/pi).^2+(Y/pi).^2));
F = delaunay(X,Y); V=[X(:) Y(:) Z(:)]; C=mean(Z(F),2);

n=2;
[Fs,Vs]=subtri(F,V,n);
Vs(:,3)=sinc(sqrt((Vs(:,1)/pi).^2+(Vs(:,2)/pi).^2)); Z=Vs(:,3);Cs=mean(Z(Fs),2);

figure('units','normalized','Position',[0 0 1 1],'Color','w'); colordef('white');
subplot(1,2,1);patch('Faces',F,'Vertices',V,'FaceColor','flat','CData',C,'FaceAlpha',0.5,'EdgeColor','k','LineWidth',2); hold on;
axis tight; axis square; grid on; hold on; view(3); axis off;
title('Original','FontSize',20);
subplot(1,2,2);patch('Faces',Fs,'Vertices',Vs,'FaceColor','flat','CData',Cs,'FaceAlpha',0.5,'EdgeColor','k','LineWidth',0.5); hold on;
axis tight; axis square; grid on; hold on; view(3); axis off;
title(['n=',num2str(n)],'FontSize',20);

### Cite As

Kevin Moerman (2021). subtri(F,V,n,uniqueOpt) (https://www.mathworks.com/matlabcentral/fileexchange/28277-subtri-f-v-n-uniqueopt), MATLAB Central File Exchange. Retrieved .

It is interesting, but I need also to find the norm of each triangle, can you?

Lomas

Lomas

M P

Kevin Moerman

Updated 28/07/2010

Kevin Moerman

Will be updated shortly. Currently requires missing function and filtering of double points using "unique" is not reliable.

##### MATLAB Release Compatibility
Created with R2015a
Compatible with any release
##### Platform Compatibility
Windows macOS Linux