#### Archived

This topic is now archived and is closed to further replies.

# Geomipmapped patches

This topic is 5393 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Finally i decided to implement geomipmapping to render my terrain. My problem is that i have to make a set of triangles to glue 2 patches with different LOD. I can do it for every side, but when i have to glue left and top edges of patch (for example) i get an odd result in the corner because of triangle sollapation. Here are 2 shots: one showing the bad result when 2 edges have to be glued and the other showing that one side glued works correct [edited by - tiutiu on August 15, 2003 8:25:17 PM]

##### Share on other sites
i made the patch with teh coarser tesselation adapt its geometry, and thus circumventing this problem..

##### Share on other sites
"Move" the extra vertices in the other direction, so that you get right-angled tiangles at the edge, with its hipotenuse (sp?) touching the lower-LOD patch. This way, you''ll always have a diagonal edge going from the corner towards the center of your patch, allowing you to avoid that problem.

Michael K.,
Co-designer and Graphics Programmer of "The Keepers"

We come in peace... surrender or die!

##### Share on other sites
U could make the coarser patches more tesselated at the edges, but this will increase the poly count.

A skirt is the best solution.

/*ilici*/

##### Share on other sites
__________..... _____
\________/ not |_____|

##### Share on other sites
Don''t collapse vertices at all. Fix the cracks by using skirts. Basically, where two patches of different LOD meet and a crack occurs, render a vertical strip. The strip''s height should follow the patch that is furthest away from you. Here''s an ASCI pic showing the terrain from the side, with a skirt rendered:
patch 1                          <-- Camera---------         |   patch 2         |---------         |         ^       skirt

This is sooo much faster. To see it in action, try my simple geomipmap demo. It contains the source for the terrain classes as well.

Sander Maréchal

GSACP: GameDev Society Against Crap Posting
To join: Put these lines in your signature and don''t post crap!

##### Share on other sites
I agree, skirts are very simple to understand and use. They are also efficient and look great!

• 19
• 10
• 19
• 14
• 19