[vtk-developers] New nonlinear celltypes

David C. Thompson dcthomp at sandia.gov
Mon Jan 9 14:22:40 EST 2006


On Mon, 2006-01-09 at 08:17, Soeren Gebbert wrote:
> Im still developing the nonlinear cells. Tcl test running well. But i
> still runing into a problem im not able to fix. I have implemented
> contouring and clipping of the new cells. The methods for that are
> quite similar. The contouring is working very well, but the clipping
> produces strange output. I have attached some pictures of the
> TriQuadraticHexahedron, to show you the point.
Two questions:
1. Could you send the LinearHexs array? 
2. Are the node numberings consistent with the figure below?
               7              14             6
               +--------------+--------------+
              /:             /:             /|
             / :            / :            / |
            /  :           /  :           /  |
         15/   :        25/   :        13/   |
          +--------------+--------------+    |
         /:    :        /     :        /|    |
        / :  19+......./....23+......./.|....+18
       /  :   .:      /       :      /  |   /|
     4/   :  . :   12/        :    5/   |  / |
     +--------------+--------------+    | /  |
     |    :.   :    |   26    :    |    |/   |
     |  20+    :    |    +    :    |  21+    |
     |   .:    :    |       10:    |   /|    |
     |  . :   3+....|.........+....|../.|....+
     | .  :   .     |        .     | /  |   / 2
     |.   :  .    22|       .    17|/   |  /
  16 +--------------+--------------+    | /
     |    :.        |     .        |    |/
     |  11+.........|.24.+.........|....+
     |   .          |   .          |   / 9
     |  .           |  .           |  /
     | .            | .            | /
     |.             |.             |/
     +--------------+--------------+
     0              8              1

Linear hexahedra should have nodes ordered like:
  {0,8,24,11,16,22,26,20}
for example. I'll be glad to check the consistency of the array if you
send it. If LinearHexs is the same as the array in
vtkQuadraticHexahedron, then you must have the mid-face points ordered
as shown above. I don't see anything wrong with the clipping routine.

Also, the two routines you sent have this comment:
>   //clip each linear quad separately
                       ^^^^ I assume you really mean hex here.

	David




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