bugGNU Octave - Bugs: bug #55014, Property VertexNormals not updated...

 
 

bug #55014: Property VertexNormals not updated when Vertices are

Submitted by:  Guillaume <gyom>
Submitted on:  Mon 12 Nov 2018 01:44:36 PM UTC  
 
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  None
Originator Name:  Guillaume Open/Closed:  Closed
Release:  dev Operating System:  Any

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Mon 19 Nov 2018 12:29:54 PM UTC, comment #4: 

Thanks for testing.

Closing as fixed.

Markus Mützel <mmuetzel>
Project Member
Mon 19 Nov 2018 10:28:30 AM UTC, comment #3: 

Thank you Markus, it works perfectly now!

Guillaume <gyom>
Fri 16 Nov 2018 07:11:44 PM UTC, comment #2: 

I pushed a patch here that fixes the issue for me:
http://hg.savannah.gnu.org/hgweb/octave/rev/fda3bc89c528

The results for the example script with that changeset:

ans =

0.196148 0.972595 -0.124835
0.210776 0.951005 -0.226191
0.052961 0.802618 0.594137

ans =

0.197744 0.972390 -0.123917
0.174780 0.959882 -0.219266
0.054484 0.801638 0.595322

ans =

0.199261 0.972198 -0.122986
0.263109 0.937257 -0.228742
0.055405 0.800945 0.596169

Marking as ready for test.

Markus Mützel <mmuetzel>
Project Member
Tue 13 Nov 2018 12:14:34 AM UTC, comment #1: 

I'm really sure this is just because there isn't a listener on the Vertices property which fires when the Vertices are changed and calls the function to update the VertexNormals.

This can be mimicked with addlistener(), but it probably should be coded in C++.  For example, if you update xdata on a patch, the Face and Vertices properties are automatically changed.

Rik <rik5>
Project Administrator
Mon 12 Nov 2018 01:44:36 PM UTC, original submission:  

If you download the Stanford Bunny mesh and run the following:

% http://www-static.cc.gatech.edu/data_files/large_models/bunny.ply.gz
M = struct('vertices',[],'faces',[]);
fid = fopen('bunny.ply','rt');
while true
    l = fgetl(fid);
    if strcmp(l,'end_header'), break; end
end
nv = 35947; nf = 69451;
M.vertices = fscanf(fid,'%f %f %f',[5 nv])';
M.vertices = M.vertices(:,1:3);
M.faces    = fscanf(fid,'%d %d %d %d',[4 nf])';
M.faces    = M.faces(:,2:4) + 1;
fclose(fid);

figure; ax = axes;
axis(ax,'equal');
axis(ax,'off');
hp = patch(M,...
    'FaceColor', 'b',...
    'EdgeColor', 'none',...
    'Parent',ax);
camlight(ax);
camlight(ax,-80,-10);
lighting(ax,'gouraud');
set(hp,'FaceVertexCData',rand(nv,1), 'FaceColor','interp')

for i=1:3
    N = get(hp,'VertexNormals');
    normN = sqrt(sum(N.^2,2));
    normN(normN < eps) = 1;
    N     = bsxfun(@rdivide,N,normN);
    N(1:3,:)
    set(hp,'Vertices',get(hp,'Vertices')+N/400);
    drawnow
end

Matlab displays:

ans =

  3x3 single matrix

    0.1962    0.9726   -0.1248
    0.2108    0.9510   -0.2262
    0.0530    0.8026    0.5941


ans =

  3x3 single matrix

    0.1977    0.9724   -0.1239
    0.1748    0.9599   -0.2193
    0.0545    0.8016    0.5953


ans =

  3x3 single matrix

    0.1993    0.9722   -0.1230
   -0.1381    0.9828   -0.1223
    0.0554    0.8009    0.5962

while Octave displays the same initial values:

ans =

   0.196148   0.972595  -0.124835
   0.210776   0.951005  -0.226191
   0.052961   0.802618   0.594137

ans =

   0.196148   0.972595  -0.124835
   0.210776   0.951005  -0.226191
   0.052961   0.802618   0.594137

ans =

   0.196148   0.972595  -0.124835
   0.210776   0.951005  -0.226191
   0.052961   0.802618   0.594137

Guillaume <gyom>

 

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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-11-19 mmuetzel StatusReady For Test => Fixed
        Open/ClosedOpen => Closed
    2018-11-16 mmuetzel StatusConfirmed => Ready For Test
    2018-11-13 rik5 StatusNone => Confirmed

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