Mesh generated at run-time gets frustum-culled too early

Question

I have a mesh generation function that gets called at runtime OR in the editor:

void GenerateAtRunTime() { if (!generated && someCriterion) { GetComponent<MeshFilter>().sharedMesh = Generator.Generate(/* arguments */); generated = true; } }

[ContextMenu("Pre-generate")]
void PreGenerate() {
    if (!generated) {
        GetComponent<MeshFilter>().sharedMesh = Generator.Generate(/ arguments /);
        generated = true;
    }
}

if I call it from the editor, all is fine. If I don't the mesh is culled too early: as soon as the center of bounds is out of view, as if it's bounds had size of 0.

The Generator.Generate is like:

Mesh mesh = new Mesh(); Vector3[] v = new Vector3[vtxCount]; Vector2[] uv = new Vector2[vtxCount]; Color[] c = new Color[vtxCount]; int[] tri = new int[triCount];

 // .... actually generate here .....

 mesh.vertices = v;
 mesh.colors = c;
 mesh.uv = uv;
 mesh.triangles = tri;
 mesh.RecalculateBounds();

 return mesh;

(I know that assigning triangles recalculates bounds, I'm just that desperate)

as a debugging help I set up the following:

[ContextMenu("Print me")] void PrintMe() { Debug.Log(string.Format("{0} renderer bounds: {1}", gameObject.name, GetComponent<MeshRenderer>().bounds)); Debug.Log(string.Format("{0} mesh bounds: {1}", gameObject.name, GetComponent<MeshFilter>().sharedMesh.bounds)); }

void OnDrawGizmos()
{
    Gizmos.DrawWireCube(renderer.bounds.center, renderer.bounds.size);
}

...and bounds seem fine and identical in either case. What am I missing when generating meshes on the fly?

Answer 1

Best Answer

Answer by femi · Jan 09, 2011 at 12:43 AM

I'm not sure why (and I would like to hear the explanation) but the following has solved the problem: the generator now doesn't create a new mesh but modifies a mesh passed as an argument. Script that triggers the generation has become:

void GenerateAtRunTime() {
    if (!generated && someCriterion) {
        Generator.Generate(GetComponent<MeshFilter>().mesh, /* other arguments */);
        generated = true;
    }
}

(if I understand correctly, accessing mesh property creates a mesh when there wasn't one, but apparently it actually does something else to it behind the scene).

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Answer 2

Answer by UnLogick · Jul 05, 2011 at 02:38 PM

I had the exact same problem. And my setup didn't allow me to use your solution.

I knew you were on the right track with the mesh bounds not being handled properly. Since collision with the same mesh worked fine, I reasoned that the MeshRenderer or MeshFilter was the one who needed to be poked.

So I tried playing around with the notifications and it turned out that, this failed:

 renderInfo.mesh.RecalculateBounds();
 renderInfo.gameObject.GetComponent<MeshFilter>().mesh = renderInfo.mesh;

And this succeeded:

 renderInfo.gameObject.GetComponent<MeshFilter>().mesh = renderInfo.mesh;
 renderInfo.mesh.RecalculateBounds();

So this is clearly a bug, either RecalculateBounds doesn't work when the mesh isn't attached to a transform, or setting the mesh property of the MeshFilter doesn't update/notify properly.

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Answer 3

Answer by KingSharaman · Mar 10, 2012 at 12:53 AM

Use RecalculateBounds() after you assign the mesh to a MeshFilter component. So for example in C#:

GetComponent().mesh = aMeshObject; aMeshObject.RecalculateBounds();

This way it will recalculate renderer bounds.

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Answer 4

Answer by Lemon · Apr 14, 2011 at 04:33 AM

Had a similar issue, posted an answer on this thread:

See http://answers.unity3d.com/questions/29948/disable-frustum-culling/52479#52479

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UnLogick · Jul 05, 2011 at 02:39 PM 0

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Mesh generated at run-time gets frustum-culled too early

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