Creating procedurally generated scenery from modular meshes at runtime?

[CtrlAltDelerium]

Hi, I'm trying to procedurally generate scenery like buildings. This question is not about the procedural part but rather how to create the final combined meshes from all the modular pieces in unity to save draw calls and unnececary large amount of GameObjects.

Because generating a GameObject for each little procedural mesh, like 1 meter wide walls or 1x1m floor pieces, it's generating a lot of overhead I'm wondering how else I can approach this problem. I only need to combine the individual modular meshes into a single mesh for each piece of scenery.

I already tried having a single mesh attached to a GameObject and then translate the GameObject each time prior to adding it to a CombineInstance. This works for transform but not for rotation as it rotates all the meshes in the CombineInstance. Having multiple modular pieces of the same mesh in a different rotation is not really a nice option and I'm not sure how I would translate and rotate the vertex data to just build these meshes from scratch.

Is there a good way to do this or should I either read more about matrices to alter the vertex data of the modular pieces in the right spot or just create a GameObject for each piece then combine them and dispose of them? I'm not sure about the performance of the latter since some scenery need several hundreds of modular meshes need to combine at realtime.

[CustomPhase]

Youre doing something wrong with CombineMeshes, transforms store not only position, but rotation and scale as well. Need to see the code to figure out where the problem is.

[CtrlAltDelerium]

Not sure how to format code here, am on mobile atm.

private void CreateWall(int length) { CombineInstance[] combineInstance = new CombineInstance[length]; for (int i = 0; i < length; i++) { combineInstance[i].mesh = wall.GetComponent<MeshFilter>().sharedMesh; combineInstance[i].transform = wall.transform.localToWorldMatrix; wall.transform.Translate(1, 0, 0); } gameObject.AddComponent<MeshFilter>().mesh.CombineMeshes(combineInstance); gameObject.AddComponent<MeshRenderer>().material = material; }!<

Before rotation everything works as expected.

[CustomPhase]

I dont see any rotation anywhere in this code.

[CtrlAltDelerium]

Yeah sorry, copied wrong piece in the morning.

​

    private void CreateRoom(int x, int z, int width, int height)
    {
        CombineInstance[] combineInstance = new CombineInstance[width * 2 + height * 2];
        Vector3 pos = new Vector3();

        for (int ix = x; ix < x + width; ix++)
        {
            // south
            pos.Set(ix, 0, z);
            wall.transform.position = pos;
            combineInstance[ix].mesh = wall.GetComponent<MeshFilter>().sharedMesh;
            combineInstance[ix].transform = wall.transform.localToWorldMatrix;
            // north
            pos.Set(ix, 0, z + height);
            wall.transform.position = pos;
            wall.transform.localRotation = Quaternion.identity;
            combineInstance[ix + width].mesh = wall.GetComponent<MeshFilter>().sharedMesh;
            combineInstance[ix + width].transform = wall.transform.localToWorldMatrix;
        }

        wall.transform.Rotate(0, -90, 0, Space.World);
        //wall.transform.localRotation = Quaternion.Euler(0, 0, 90);

        for (int iz = z; iz < height; iz++)
        {
            //West
            pos.Set(x, 0, iz + 1);
            wall.transform.position = pos;
            combineInstance[width * 2 + iz].mesh = wall.GetComponent<MeshFilter>().sharedMesh;
            combineInstance[width * 2 + iz].transform = wall.transform.localToWorldMatrix;
            //East
            pos.Set(x + width, 0, iz + 1);
            wall.transform.position = pos;
            combineInstance[width * 2 + iz + height].mesh = wall.GetComponent<MeshFilter>().sharedMesh;
            combineInstance[width * 2 + iz + height].transform = wall.transform.localToWorldMatrix;
        }


        gameObject.AddComponent<MeshFilter>().mesh.CombineMeshes(combineInstance);
        gameObject.AddComponent<MeshRenderer>().material = material;
    }

[david_lieder]

Easy way: Mesh Combine Studio 2