Dynamic Terrain Manipulation, TreePrototypes, Prefabs, etc.

In order to dynamically add trees to terrain objects via scripting, I create a TreePrototype object for each tree my script builds. In order to create a TreePrototype object, I have to create a Prefab object to populate with the tree before passing it to the TreePrototype.

Unfortunately, I can't figure out any possible way to create a prefab object via scripting.

I am currently creating 10 empty prefabs in the editor, assigning them to an array, and then later populating them with trees in my script, assigning them to TreePrototypes, and placing them on terrains - but this is an incredibly dumb solution.

How do I initialize a Prefab object via scripting?
Note that Prefabs are somehow different from GameObjects - passing a GameObject to a TreePrototype does not work.

Thanks,

-Aubrey

 

Interesting concept.

EditorUtility class ( http://unity3d.com/support/documentation/ScriptReference/EditorUtility.html ) has a set of prefab functions. Although, as the name suggests, its an editor class, so wont work outside the editor. It seems that creating prefabs at runtime is not possible.

 

Exactly

I have played with the EditorUtility prefab system - but only functioning as an EditorScript is a dealbreaker.

If it really is impossible to create terrain details at runtime from scratch due to their (rather strange) dependance on prefabs, this is a huge oversight on Unity's part!

I suppose I should submit a bug report...

 

Theres no bug, so no use submitting bug reports...

As far as i know, the terrain system was done by a third party and later integrated into Unity, and judging by the lack of documentation, i guess they dont want us messing with it. I too hate how inflexible and closed in general the terrain system is, but it makes sense.

 

I understand with your position, but I have put a ton of effort into "prying open" the terrain system - and I can now do practically anything with a terrain through scripting except for creating trees and details from absolute scratch

I'll abstain from bug reporting for now and stick with my terribly ugly preprefab hack, but I sure hope Unity sees fit to breath some new life into documented terrain scripting in the future...

 

Its possible to change the terrain hight at a certain point during runtime?

 

Yes, and there was no need to ask the question in this outdated thread. There are other threads that detail all kinds of runtime Terrain manipulation.

The method you want is

terrain.terrainData.SetHeight(int heightmapX, int heightmapY, float normalizedHeight)

 

The tree prefabs and tree instances are two different things entirely.

For each type of tree you want, you need a tree prefab - one per type. Usually you can (and should) set this up in the editor not at runtime. If you need to generate the terrain 100% from scratch you still can though, just by replacing this array with a new array of prefab references:

http://unity3d.com/support/documentation/ScriptReference/TerrainData-treePrototypes.html

After you adjust that array, make sure you run yourTerrain.terrainData.RefreshPrototypes();

Now your terrain has the prototype(s) you want to spawn, time to actually to about adding the tree instances (the individual trees).

Code (csharp):

1.  
2. public void SpawnTree(Vector3 position){
3.         if (MapTerrain.terrainData.treePrototypes.Length > 0){
4.             TreeInstance newInstance = new TreeInstance();
5.             newInstance.position = WorldToTerrainPoint(position);
6.             newInstance.heightScale = 0.3f;
7.             newInstance.widthScale = 0.3f;
8.             newInstance.prototypeIndex = 0;
9.             newInstance.lightmapColor = Color.white;
10.             newInstance.color = Color.white;
11.             MapTerrain.AddTreeInstance(newInstance);
12.             MapTerrain.Flush();
13.         }
14.     }
15.  

Code (csharp):

1.  
2. TreeInstance newInstance = new TreeInstance();
3. newInstance.position = new Vector3(wherever you want it);
4. newInstance.heightScale = 1; newInstance.widthScale = 1;
5. newInstance.prototypeIndex = whatever index you want (if you only have 1 prototype, just set this to zero)
6. newInstance.lightmapColor = Color.white; If you don't set the lightMap color your trees will appear as black silhouettes
7. newInstance.lightmapColor = Color.white;
8.  
9. YourTerrain.AddTreeInstance(newInstance);
10. MapTerrain.Flush();
11.  

If you are generating a lot of trees, I suggest making your own TreeInstance[] - populating that - and replacing the YourTerrain.terrainData.treeInstances variable with your own array instead of pushing each individual tree (for performance reasons).

NOTE:
The location of your trees is based on a float from 0 to 1, it is NOT a world position. (so 0,0 = bottom right corner of the terrain, 1,1 = top left, or vice versa - don't remember off the top of my head).

For the heights yea, SetHeight() is the ticket there. I *STRONGLY* recommend using SetHeights though and setting the entire hightmap in a single call, as the performance impact of calling SetHeight for every pixel in the heightmap is huge.

EDIT:
/facepalm - sorry, didn't realize this thread was a necro.

@Furfire - yea, you want SetHeight/SetHeights (the same advice applies, do it all in a single call if you can - much faster). You *may* need to call YourTerrain.Flush() after you do this to see the changes, not sure if the heightmap requires a flush or not off the top of my head.

 

Apologies, I ran into this thread on Google and didn't realize how old it was XD