[SOLVED] Random holes in tesselated mesh

[Rob]

We created a large modular cave for our game but when im moving around inside the cave random section at bottom and top of the screen seem to dissapear

Anyone knows whats causing this? It seems like some kind of occlusion but im not sure

 

I think it is because the polygons of the non tesselated mesh seems to be behind the player while the tesselated polygons are infront of the player

any way to fix this? I find it quite strange that it calculates the occlusion on the low poly version instead of the tesselated version

 

Ive attached a screenshot of the issue

[Rob]

I already fixed it myself by using larger polygons inside the cave, now the polygons still do dissappear every now and then but its barely noticable

[Guest anet]

Have you tried to change ZNear value for your player? Does it change anything?

 

See this page https://developer.un...#setZNear_float for reference

[Rob]

I changed the near clipping in the engine under Tool > Camera but this didnt help

[Guest anet]

And do these random holes appear in editor mode? or in game mode?

Editor has it's own player and when you change settings under Tool > Camera, you change editor Player's settings.

[Rob]

Editor mode, I didnt check it ingame mode

even after changing the settings the problem persisted

 

Here is another screenshot of the problem

on the left you see the dissapearing polygon, so when I turn the tesselation scale slider to 0 the polygon moves out of my view as seen on the right

[Guest anet]

I've consulted our CTO.

You need to correct a constant in the following shader: data/core/shaders/default/mesh/control_base.shader

 

Replace 1.2f with a greater value.

But you should note, that this fix will cause a performance drop.

[manguste]

Just to get you the idea of what's going on: you seem to have a very high extrusion that causes this bug. Ulf is right, in most cases tessellation is not used to change the relief this drastically. Maybe it makes sense to make your coarse meshes more extruded.

 

Tessellation is done only for polygons in the view frustum, plus some polygons right outside it so you will not see gaps when tessellated polygons are displaced too far. This constant defines over what distance outside the view frustum polygons are tessellated as well. So basically the higher this value, the longer it takes for the graphics card to draw the frame.

[Rob]

Yeah we found out the hard way that tesselation isnt good for macro detail, but it gave us a good and easy way to see what we wanted our cave to look like!

we already changed the cave mesh so it has the rocky details itselfand the tesselation can be used for micro details to smooth things out

Thanks for all the help tho!

[manguste]

Good it's cleared up now :) I'll add it to docs, i.e. tessellation material description to avoid further confusion.