River through hole in Terrain?

[Volumenkaiser]

Hi,

I wanted to create a scenic river flowing out of a mountain, so I decided to create a hole in the terrain and embellish the surroundings with stones. However, I encountered an issue where the rendering of the river stops at the area where the terrain would be. (trasnlated by chatGPT 🙂)

[Volumenkaiser]

If you are able to speak German, I would be happy about German explanations.

[Bryan]

Can you please see if you have Gaia sea level enabled. If so please turn that off. Then you should be able to go lower than that. 

[Bryan]

On the river extension.

[Volumenkaiser]

That isnt the ending of the River, its the beginning.
tried it anyway but didnt changed enything.

[Bryan]

Can you send me the river profile settings 

 

[Volumenkaiser]

https://drive.google.com/file/d/136yhsX_jgLyKPrxHHTeVWQc6hnNtPoIK/view?usp=sharing

what i forgot and maybe is important, when i go through the Terrain, where it would be without the Hole, i see the River 

[Bryan]

Sorry I mean can you send me a screenshot of what you are seeing and a screenshot of the river profile?

[Volumenkaiser]

i dont know why, but kno i see the River behind the Terrain, but it doesnt look how it should be:
https://drive.google.com/file/d/1RETPh1TLrL_BtS7k2lafxqK4yf4Zd_bm/view?usp=sharing

[Bryan]

I believe the issue is that there is nothing underneath it. 
Until you get close to it, its acting like the ocean then when the camera is close and you go in the hole its acting like a river. 

Does this act the same when the cave is there? 

Can you test this theory by adding a plane under the water? 
Where the hole is created? 
 

[Volumenkaiser]

ok, tried puting a plane underneath and a terrrain, after both it still looked the same

 

[Bryan]

Can you please tell me what Render Pipeline you are using? 

 

[Volumenkaiser]

URP

[Bryan]

I am talking with the team to find a solution to this I have been able to replicate the issue, but unsure as to why it's happening. We will try to figure out a solution to this as quickly as possible.

[Peter]

Hi @Volumenkaiser; we reviewed this internally, and the problem is that the river system was designed to read the required width from the terrain surface. When creating a hole into the terrain and letting the river run inside, it cannot determine the width correctly anymore as it can not find the surface inside to collide with.

There is a possible workaround for this:

1. Design your river outside the terrain as you want it, especially make sure that the terrain is carved as you want it to be



2. Make a backup of the terrain data object.


You can do so by making a manual copy of it in the file system, or using a source control system to restore it later. If you are using Gaia, there is also a system for that in the Session Manager. Make sure you take the terrain backup at the point where the river outside of the terrain is as you want it.

3. Without digging a hole yet, position the river spline points inside the terrains how you want them. The carve preview should show that you are digging quite a big gap into the terrain, since the spline runs so deep from the surface:




4. Use the carve feature of the river extension again to carve that deep gap:



5. Use the "Bake River" function on the river extension:



This will create an independent Game object with a static river mesh on it in your scene.

6. Delete the original GeNa spline curve - this is important because if there are changes made later to the terrain, GeNa can still update the river

7. Restore the backup of the terrain data object - because the river is only a "dumb" static mesh now, it should keep its shape:



8. Now you can dig the hole and decorate the cave entrance:

Hope this helps! I know this is not an ideal solution, but as mentioned, the river system was never originally designed to go inside the terrain. To support that properly, we would need to invest far more development time to separate between "inside" and "outside" river generation logic.