DelaunayMesh - BUG

Software: Away3D 4.x

yyovchev, Newbie
Posted: 13 July 2012 12:33 AM   Total Posts: 29

I am playing with Delaunay extrusion and it is not drawing my mesh correctly. I tried same coordinates with Linear Extrude and it works fine. Here is example

var vec= new Vector.<Vector3D>;
vec.push(new Vector3D(4,0,-534.6));
vec.push(new Vector3D(1338.4,0,-534.6));
vec.push(new Vector3D(1338.4,0,-4));
vec.push(new Vector3D(914.4,0,-4));
vec.push(new Vector3D(914.4,0,-170.6));
vec.push(new Vector3D(4,0,-170.6));

var 
plane= new DelaunayMesh(matvecDelaunayMesh.PLANE_XZfalse,falsetrue ); 

I hope this is easy to resolve.

 

Image Attachments
delaunay.png
   

Richard Olsson, Administrator
Posted: 13 July 2012 07:20 AM   Total Posts: 1192   [ # 1 ]

That’s a good catch. Please file a bug report on GitHub and we will try to fix that for 4.1. We’re too close to 4.0 release to be able to accept any new bug fixes that aren’t extremely simple to fix and low-risk, or complete showstoppers. But we are planning on reworking parts of the extrusions tools anyway for 4.1, so it would be great to track this issue for then!

The issue tracker is at http://github.com/away3d/away3d-core-fp11/issues

Thanks!

 

   

yyovchev, Newbie
Posted: 13 July 2012 09:54 AM   Total Posts: 29   [ # 2 ]

Is there any temporary solution for this problem so I could be able to continue on my work?

 

   

Richard Olsson, Administrator
Posted: 13 July 2012 09:56 AM   Total Posts: 1192   [ # 3 ]

I would guess that breaking up your mesh into several parts where all parts are convex. I’m assuming the issue is because your path is concave.

Convex vs concave polygons are explained here:
http://en.wikipedia.org/wiki/Convex_polygon

 

   

Avatar
Fabrice Closier, Administrator
Posted: 13 July 2012 10:36 AM   Total Posts: 1260   [ # 4 ]

This not a bug, this is the expected behavior. The class doesn’t have atm any concept of contour, path etc..  It is on the todo to add ear clipping capabilities.

 

   

baggaamit, Newbie
Posted: 28 August 2013 09:22 PM   Total Posts: 3   [ # 5 ]

Is this issue resolved? i have added triangulation for my vertices but have issues with the UV data. Any Help would be appreciated.

 

   

allensmith, Newbie
Posted: 03 March 2015 07:55 AM   Total Posts: 4   [ # 6 ]

I also meet some issue about Delaunay and mesh.I am a issn barcode designer and my work is to do barcode design using c#.net.But recently i need to do something different.

I am currently working on a structural mechanics problem in which I need to cut an existing 3D surface mesh in order to use symmetry in MATLAB or GMSH.

First attempt: I obtained the symmetry by first deleting all nodes on the negative x-axis; then use delaunayTri() to get 3D tetrahedral mesh. After which, I used freeboundry() matlab function to get the surface mesh. Using this approach, some of the nodes were ignored hence I lost the actual geometry (i.e. biconcave shape in 3d) and symmetry.

Second attempt: I obtained the symmetry by first deleting all nodes on the negative x-axis; then use AlphaHull() matlab function from file exchange which uses an alpha shape algorithm. Here, I have to define a scalar parameter called alpha radius whose value affect the quality of the surface mesh but no well defined range hence I can’t automate for larger mesh; more importantly, there are some residual surface or tetrahedral mesh within the 3D surface mesh generated.

Attached are 3 files (in one zip file):

  Original GMSH file;
  Extracted node coordinates and
  Extracted element connectivity array from GMSH file (txt format).

https://www.dropbox.com/s/7xwkyvqy13k5o33/get_symmetry.zip?dl=0

N.B: I do not wish to add additional nodes to the new symmetry as the current node coordinates and connectivity are very important in my computation, but if compulsory, additional nodes may be introduced. I will however appreciate any assistance and/or suggestions.

Thank you in advance.

 

Image Attachments
1.png
   
   

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