adding mesh collider in run time slow?

Questions & Answers
1

i would need an advice about adding mesh colliders in run time.
this makes size of the build much smaller but it takes some time to add a collider, especially mesh colliders.

i wanted to do it in the coroutine but it somewhat hangs, but without coroutine it freezes.
here is the code to add mesh colliders to transforms:

void Prepare(){
		
	StartCoroutine(StartPrepare());
}

IEnumerator StartPrepare()
{
		
   Transform[] objects = prefabToPrepare.GetComponentsInChildren<Transform>();
	    		
   for(int i = 0; i < objects.Length; i++)
   {
  	  if(objects*.gameObject.renderer)*
  • {*
    _ objects*.gameObject.AddComponent();_
    _ Debug.Log("i: " + objects.name);
     yield return null;
    }
    }
    }*
    i am doing something wrong here, uncommenting add mesh collider line debug statements are printed, adding box collider is much faster. meshes are not that high poly…?_
2

It simply takes a long time to “import” as it were, a mesh.

(Please note … as Eric critically points out below, the problem is the mesh collider, not the mesh-that-draws-stuff.)

You “just can’t” - that’s it. You’re doing nothing wrong, it’s just an inherent limitation of today’s pipeline, hardware and software.

If you build something dynamically, say a Dragon, that’s great. At start-up time or between scenes you can “import” that new mesh you’ve created dynamically.

But the current state of the art 3D game pipeline - you just can’t “import” your new mesh in real time. That’s that.

To be clear, the actual calculation time for you to make a mesh is nothing. The problem is “importing” it to the pipeline. (To be clear, issues like foreach, coroutines, etc, are totally irrelevant.)

There are many long-winded discussion about this basic limitation on this site, eg

“Basically putting new mesh in to a scene is … slow ! it just takes a long time to cycle in the new mesh. That’s that really.”

Hope it helps, sorry for the bad news ! :open_mouth:

3

Late answer but I found that chopping my meshes up before adding a mesh collider to them significantly reduced the overall time required. In my case this automatic subdivision was relatively simple as it was for user generated heightfields on a regular grid.

4

My solution was to recycle the GameObjects

  • put them in a Stack
  • Set Renderer.Enabled to false
  • pop the stack when you need an object, if the stack is empty you create a new GO.