Inconsistent procedural terrain

[randomUsrname]

I have this code that works great for placing objects procedurally. However, the perlin noise is inconsistent, and it slightly changes when it is updated with new player position values. Any fixes for this?

using NUnit.Framework;
using UnityEditor;
using UnityEngine;

public class ChunkGenerationScript : MonoBehaviour
{
    public int gridSizeX = 5;
    public int gridSizeY = 5;
    public int ChunkScale;
    public float NoiseScale, NoiseHeight;
    public GameObject Floor1, Floor2, Floor3;
    public Transform Player;
    public int Seed;
    public float RequiredHeight;
    Vector2 PreviousPos;
    Vector2 PlayerPos;
    public int DistanceToChange;


    void Start()
    {
        PreviousPos = new Vector2(Player.position.x, Player.position.z);
    }

    private void Update()
    {
        PlayerPos = new Vector2(Mathf.Floor(Player.transform.position.x), Mathf.Floor(Player.transform.position.z));
        if (Vector2.Distance(PreviousPos, PlayerPos) > DistanceToChange) SpawnGrid();
    }

    public void SpawnGrid()
    {
        Random.InitState(Seed);
        ClearGrid();

        PreviousPos = PlayerPos;

        for (int x = 0; x < gridSizeX; x++)
        {
            for (int y = 0; y < gridSizeY; y++)
            {
                float xCoord = (((PlayerPos.x / ChunkScale) + x) / gridSizeX) * NoiseScale * Seed;
                float zCoord = (((PlayerPos.y / ChunkScale) + y) / gridSizeY) * NoiseScale * Seed;
                float Result = Mathf.PerlinNoise(xCoord, zCoord);
                Vector3 position = new Vector3(x * ChunkScale + PlayerPos.x, 0, y * ChunkScale + PlayerPos.y) - (new Vector3(gridSizeX, 0, gridSizeY) * ChunkScale / 2);
                GameObject prefab;
                if (Result >= RequiredHeight) prefab = Floor1;
                else prefab = Floor2;
                GameObject NewChunk = Instantiate(prefab, transform, transform);
                NewChunk.transform.localPosition = position;
                NewChunk.transform.localScale *= ChunkScale / 10;
            }
        }
    }

    public void ClearGrid()
    {
        for (int i = transform.childCount - 1; i >= 0; i--)
        {
            DestroyImmediate(transform.GetChild(i).gameObject);
        }
    }

#if UNITY_EDITOR
    [CustomEditor(typeof(ChunkGenerationScript))]
    public class GridSpawnerEditor : Editor
    {
        public override void OnInspectorGUI()
        {
            DrawDefaultInspector();

            ChunkGenerationScript gridSpawner = (ChunkGenerationScript)target;

            if (GUILayout.Button("Spawn Grid"))
            {
                gridSpawner.SpawnGrid();
            }

            if (GUILayout.Button("Clear Grid"))
            {
                gridSpawner.ClearGrid();
            }
        }
    }
#endif
}

[Kurt-Dekker]

@randomUsrname

However, the perlin noise is inconsistent, and it slightly changes when it is updated with new player position values. Any fixes for this?

Don’t use the player position as input if it is going to be different.

OR… use a reduced-accuracy version of the player position, such as one rounded off to a lower level of accuracy.

Perlin noise will give the same numeric output for a given input pair. Your job is to make that input pair consistent. If you truly care about accuracy, your computations should probably be in integer space, then downscaled all at once right before feeding into the Perlin function. Here’s why:

Floating (float) point imprecision:

Never test floating point (float) quantities for equality / inequality. Here’s why:

https://starmanta.gitbooks.io/unitytipsredux/content/floating-point.html

Debug.Log(2000.0f * 000.1f); is 200

Now that you have had your coffee, don’t forget about floating point imprecision: // @kurtdekker: don't forget about floating point imprecision using UnityEngine; public class FloatingPointImprecision : MonoBehaviour { void Start () { float a = 2000.0f; float b = 0.1f; float product = (a * b); float answer = 200; Debug.Log( "a = " + a); Debug.Log( "b = " + b); Debug.Log( "product of a*b = " + product); Debug.Log( "answer =…

Why Doesn't This Code Work?

This will explain it all. In an IEEE single-floating point number you can represent certain numbers perfectly and unambiguously. For instance, 0.5f is precisely represented as 0x3f000000 However, 0.1f CANNOT be precisely represented. One possible approximate representation is 0x3DCCCCCD The analogy is that you cannot show 1/3rd precisely as a decimal. 0.33 is correct to 2 decimal places 0.3333 is correct to 4 places etc. But you can never exactly represent 1/3rd as a decimal numeral. Yo…

“Think of [floating point] as JPEG of numbers.” - orionsyndrome on the Unity3D Forums

[randomUsrname]

I’ve done this with Mathf.floor, and now trying with Mathf.Round. It doesn;t seem to work

[Kurt-Dekker]

@randomUsrname

. It doesn;t seem to work

Don’t post here, start debugging.

As I pointed out, Mathf.PerlinNoise() will return the same value for the same two inputs.

If you change those inputs, the output WILL be different.

If that’s what you’re observing, that is not a bug.

If you want another behavior, then you need to specify that. At present your specification says:

@randomUsrname

when it is updated with new player position values.

So… it’s on you to decide WHY the player’s position should have anything whatsoever to do with terrain generation.

You might find it useful to work through some of the millions of Youtube terrain generation tutorials. Sebastian Lague has a ton of great ones but there are others too. This is a completely and totally solved problem so no sense in you rediscovering it piecemeal and posting each dead end you encounter.