Warped GPU Instanced Objects

Unity Engine
,
1

Hello,

This may be the wrong section, so i apologize if so. Anyways, I am learning about GPU Instancing and finding some good benefits. I am experimenting with it a bit and trying to see if I can place an instanced object in the exact right position, rotation, and scale. I appear to be understanding the position and scale portions, but the rotation part is baffling.

The issue: When i try to rotate the object using new Quaternion(x, y, z, w) or from a public field, it is distorting the object’s scale (like it is stretching it) and it is moving its position dramatically. When i followed the tutorial it used Random.rotation and that appears to rotate them properly without distortion. But getting the exact rotation is not working.

I am sure i am misunderstanding something pretty basic but after searching the forums and manuals, i believe i am not understanding the Matrix4x4 part. Not sure if that is where my issue is, but it is the only thing i am not grasping properly.

Any explanation or help is appreciated.

Here is my code:

    public int instances;

    public Mesh mesh;

    public Material[] mats;

    private List<List<Matrix4x4>> batches = new List<List<Matrix4x4>>();

    public Vector3 pos; public Quaternion rot; public Vector3 scale;

    // Start is called before the first frame update
    void Start()
    {
        int AddMatricies = 0;
        batches.Add(new List<Matrix4x4>());

        for (int i = 0; i < instances; i++)
        {
            if (AddMatricies < 1000 && batches.Count != 0)
            {
                //batches[batches.Count - 1].Add(Matrix4x4.TRS(new Vector3(Random.Range(0, 50), Random.Range(0, 50), Random.Range(0, 50)), Random.rotation, Vector3.one * 50)); //Works great
                batches[batches.Count - 1].Add(Matrix4x4.TRS(new Vector3(-35.5599f, .242317f, -36.99f), rot, Vector3.one * 103)); // Quaternion parameter does not work properly
                AddMatricies += 1;
            }
            else
            {
                batches.Add(new List<Matrix4x4>());
                AddMatricies = 0;

            }
        }
    }

    // Update is called once per frame
    void Update()
    {
        RenderBatches();
    }

    private void RenderBatches()
    {
        foreach (var Batch in batches)
        {
            for (int i = 0; i < mesh.subMeshCount; i++)
            {
                Graphics.DrawMeshInstanced(mesh, i, mats[i], Batch);
            }
        }
    }
2

How do you set the quaternion values? Only normalized quaternions correspond with rotations, so you can’t just change the x,y,z,w values any way you want.

3

I’ve tried setting it via values from the Inspector since “rot” is public. I have also tried just using “new Quaternion(value, value, value, value)” and the same thing happens.