<p>I am currently trying to reduce the tessellation levels on front facing triangles, but I also want to keep tessellation levels high on edges (so when the view vector is orthogonal to the triangle normal).</p>

<p>Some background information. My terrain system tessellates the terrain and displaces the newly created triangles using the heightfield texture. That means that each triangle edge must always have the same tessellation levels as the other triangles that share the same edge, otherwise holes will be created in the terrain.</p>

<p>I can't find a way to keep the calculations consistent for shared edges.</p>

<p>edit: I have been trying to use non-divergent data by sampling the heightfield to calculate the normal for the edges. That way regardless of the triangle. The edge tessellation levels will always be the same, but I seem to be having issues.</p>

CC BY-SA 4.0
2018-08-24T17:20:35.553Z
Nevermind I fixed this issue by sampling the heightmap to get the edge normals. That way the data isn't divergent and it won't cause cracking. However if anyone has anything useful to add, for any users in the future, then feel free!
Brady Jessup
CC BY-SA 4.0
2018-08-25T22:02:22.493Z
Glad to hear you fixed your own problem. If you'd like to, [self answers are encouraged](https://computergraphics.stackexchange.com/help/self-answer) and that would help future readers (and doesn't stop others adding alternative answers later too).
trichoplax is on Codidact now
CC BY-SA 4.0
2018-08-27T14:44:38.167Z
Good suggestion! I will do a write-up this week with pictures so I can help anyone who has issues in the future :)
Brady Jessup
<tesselation>
Proper way to reduce tessellation on front faces?
Brady Jessup
# Proper way to reduce tessellation on front faces?

(Asked by: username_0 on 2018-08-24)

I am currently trying to reduce the tessellation levels on front facing triangles, but I also want to keep tessellation levels high on edges (so when the view vector is orthogonal to the triangle normal).

Some background information. My terrain system tessellates the terrain and displaces the newly created triangles using the heightfield texture. That means that each triangle edge must always have the same tessellation levels as the other triangles that share the same edge, otherwise holes will be created in the terrain.

I can't find a way to keep the calculations consistent for shared edges.

edit: I have been trying to use non-divergent data by sampling the heightfield to calculate the normal for the edges. That way regardless of the triangle. The edge tessellation levels will always be the same, but I seem to be having issues.

**Tags:** tesselation

> **Comments:**
> **username_0**: Nevermind I fixed this issue by sampling the heightmap to get the edge normals. That way the data isn't divergent and it won't cause cracking. However if anyone has anything useful to add, for any users in the future, then feel free!  
> **username_1**: Glad to hear you fixed your own problem. If you'd like to, [self answers are encouraged](https://computergraphics.stackexchange.com/help/self-answer) and that would help future readers (and doesn't stop others adding alternative answers later too).  
> **username_0**: Good suggestion! I will do a write-up this week with pictures so I can help anyone who has issues in the future :)  

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