Create a 3D patch faces matrix from vertices matrix

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Guy Trakht
Guy Trakht 2020-6-17
编辑： Guy Trakht 2020-6-17
Hello,
im trying to convert 2D patches to 3D patches (extrude the 2D poligon) . for that purpose i already have a vertices matrix but im trying to build the faces matrix as said in the MATLAB documentation, but i cant follow the logic for 'n' lines polygon, (for example a star shape) . im looking for a function that gets the left matrix and returnes the right matrix. many thanks to the helpers
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Guy Trakht
Guy Trakht 2020-6-17
sorry for the missing data.. the 6'th point is above the 1'st , 7th' is above 2nd' and so on.. two identicle polygons - one on top the other. i hope this is more clear now

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Guy Trakht
Guy Trakht 2020-6-17
编辑：Guy Trakht 2020-6-17
function [faces_matrix] = vertices2faces (vertices_matrix)
%this function recives vertices matrix for an 'n' lines polygon and
%returnes the faces matrix - only works with extruded straight up polygons
wall_faces = zeros(length(vertices_matrix)/2,4);
for i=1:(length(vertices_matrix)/2-1)
wall_faces(i,:) = [i, i+1, i+1+length(vertices_matrix)/2, i+length(vertices_matrix)/2];
end
wall_faces (i+1,:) = [length(vertices_matrix)/2, 1, length(vertices_matrix)/2+1, length(vertices_matrix)];
top_and_bottom_faces = [1:length(vertices_matrix)/2;length(vertices_matrix)/2+1:length(vertices_matrix)];
%in a case that the tom and bottom faces are with less vertices then the walls
if length(vertices_matrix)/2<4
faces_matrix =[wall_faces; top_and_bottom_faces, top_and_bottom_faces(:,1)];
else
for j=5:length(vertices_matrix)/2
wall_faces(:,j) = wall_faces(:,1);
end
faces_matrix = [wall_faces; top_and_bottom_faces];
end
end

更多回答（1 个）

KSSV
KSSV 2020-6-17
Are you looking for something like this?
data = [-0.293 -0.404 0;
-0.475 0.154 0;
0 0.5 0;
0.475 0.154 0;
0.293 -0.404 0;
-0.293 -0.404 1;
-0.475 0.154 1;
0 0.5 1;
0.475 0.154 1;
0.293 -0.404 1]
%% the first 5 rows are the bottom vertices , the last 5 are the upper
x = data(:,1) ; y = data(:,2) ; z = data(:,3) ;
yi = linspace(min(y),max(y),10) ;
zi = linspace(min(z),max(z),10) ;
[Y,Z] = meshgrid(yi,zi);
X = griddata(y,z,x,Y,Z) ;
surf(X,Y,Z)
  1 个评论
Guy Trakht
Guy Trakht 2020-6-17
no, just want to create the face matrix from the given vertices. without meshing any data.
i appreciate your help

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