Part of the Khronos Group
OpenGL.org

The Industry's Foundation for High Performance Graphics

from games to virtual reality, mobile phones to supercomputers

Results 1 to 3 of 3

Thread: Shadow volume bug

  1. #1
    Junior Member Regular Contributor
    Join Date
    Apr 2002
    Location
    St. Louis, MO USA
    Posts
    177

    Shadow volume bug

    Take a look at this screenshot to see the bug I'm getting: http://home.earthlink.net/~ioquan/shadowbug.jpg .

    Has anyone ever had this problem with shadow volumes or know what causes this?

    I think it may be in the way I set up connectivity for the silhouette determination. I printed out the output for my adjacency information and noticed that there were more edges than expected which did not get assigned a neighbor (like one out of every 30 edges or so). I wonder if these edges which arent getting assigned a neighbor are responsible for the bug. Maybe the model file has duplicate vertices so my algorithm doesnt recognize them as being shared between the two adjacent triangles?? Does this sound like it would cause the phenomenon in the screenshot?

    Any help with locating or solving the problem would be appreciated.

  2. #2
    Member Regular Contributor
    Join Date
    May 2001
    Location
    Beloit, Wisconsin
    Posts
    473

    Re: Shadow volume bug

    Looks like the mesh might not be completely closed.

  3. #3
    Junior Member Regular Contributor
    Join Date
    Feb 2001
    Location
    UK
    Posts
    124

    Re: Shadow volume bug

    Hmm it can be caused by some "model error". I have had similar problems by edges used by 3 triangles (mdl/md3 models Dont'ask me how that came in the model.)
    The solution I use is setting all neighbours for this edge to null so you always cast a shadow with it. It may not be the best solution but it only happens for a few edges in a model normally.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •