vb_mesh_area

 area of patch triangle
  area = vb_mesh_area(V,F)
 --- Input
 V(n,1:3) : vertex of surface
 F(m,1:3) : patch index
 --- Output
 area(m) : area of patch triangle F(m,1:3)

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function    [sarea, asum, adev] = vb_mesh_area(V,F)
0002 % area of patch triangle
0003 %  area = vb_mesh_area(V,F)
0004 % --- Input
0005 % V(n,1:3) : vertex of surface
0006 % F(m,1:3) : patch index
0007 % --- Output
0008 % area(m) : area of patch triangle F(m,1:3)
0009 %
0010 % Copyright (C) 2011, ATR All Rights Reserved.
0011 % License : New BSD License(see VBMEG_LICENSE.txt)
0012 
0013 Npatch = size(F,1);          % number of patch
0014 
0015 % 三角面３頂点のインデックス
0016 F1     = F(:,1);
0017 F2     = F(:,2);
0018 F3     = F(:,3);
0019 
0020 % ３角面の法線ベクトル
0021 xxf  = vb_cross2( V(F2,:)-V(F1,:) , V(F3,:)-V(F1,:) );
0022 
0023 sarea = sqrt(sum(xxf.^2,2));
0024 
0025 asum=sum(sarea)/Npatch;
0026 
0027 adev=sqrt(sum((sarea-asum).^2)/Npatch);