Trying to set heightmaps depending on image texture colors through code

Question

Well I'm trying to set the heightmap of a terrain from an image / texture colors (from pixels), I made this simple example:

using UnityEngine;

public class TerrainExample : MonoBehaviour
{
    public Texture2D map, grassTexture;
    public float amp = 8;
    public Color waterColor = new Color(0.427f, 0.588f, 0.737f); //new Color32(127, 168, 200, 255); //0.427, 0.588, 0.737

    private Vector3 mapPlane = new Vector3(4200, 0, 3000);

    public void Start()
    {
        GameObject TerrainObj = new GameObject("TerrainObj");
        TerrainData _TerrainData = new TerrainData();
        Debug.Log(new Vector3(mapPlane.x, 600, mapPlane.z));
        _TerrainData.size = new Vector3(mapPlane.x / (1.6f * amp), 600, mapPlane.z / (1.6f * amp));
        _TerrainData.heightmapResolution = 4096;
        _TerrainData.baseMapResolution = 1024;
        _TerrainData.SetDetailResolution(1024, 16);

        //Set terrain data
        int _heightmapWidth = _TerrainData.heightmapWidth,
            _heightmapHeight = _TerrainData.heightmapHeight;
        float[,] heights = new float[_heightmapWidth, _heightmapHeight];
        float stepX = (float)map.width / _heightmapWidth, stepY = (float)map.height / _heightmapHeight;
        int w = 0;
        for (float i = 0; i < map.width; i += stepX)
            for (float k = 0; k < map.height; k += stepY)
            {
                int ii = (int)i, kk = (int)k, i2 = (int)(i / stepX), k2 = (int)(k / stepY);
                heights[i2, k2] = map.GetPixel(ii, kk) == waterColor ? .25f : .5f;
            }
        _TerrainData.SetHeights(0, 0, heights);

        //Set terrain grass texture
        SplatPrototype terrainTexture = new SplatPrototype();
        terrainTexture.texture = grassTexture;
        SplatPrototype[] splatPrototype = new SplatPrototype[1] { terrainTexture };
        _TerrainData.splatPrototypes = splatPrototype;
        TerrainCollider _TerrainCollider = TerrainObj.AddComponent<TerrainCollider>();
        Terrain _Terrain2 = TerrainObj.AddComponent<Terrain>();
        _TerrainCollider.terrainData = _TerrainData;
        _Terrain2.terrainData = _TerrainData;
        TerrainObj.transform.position = -mapPlane * 10 / 2 + Vector3.up * 100;
    }
}

My map texture is the following:

The original map has 7000x5000 px, and my heightmap has 4096 units. So, I have to make a little translation, by calculating the step of every iteration (as you can see in line 25)

What I do is simple, I only put a 0.25f of the height (600/4 = 150) when there is water and 0.5f of the height (600 / 2 = 300) when there is something different from water. (Line 31)

But for some reason I only get this weird lines across the terrain:

What I'm missing???

Here is a Unitypackage.

Answer 1

I didn't really bother assigning the texture, I'll let you do that.

• create a new scene
• add a terrain
• add the following component

Code:

using UnityEngine;

namespace Assets
{
    public class Test : MonoBehaviour
    {
        public Texture2D Texture2D;

        private void OnEnable()
        {
            var terrain = GetComponent<Terrain>();
            var data = terrain.terrainData;
            var hw = data.heightmapWidth;
            var hh = data.heightmapHeight;
            var heights = data.GetHeights(0, 0, hw, hh);

            for (var y = 0; y < hh; y++)
            {
                for (var x = 0; x < hw; x++)
                {
                    // normalize coordinates
                    var x1 = 1.0f / hw * x * Texture2D.width;
                    var y1 = 1.0f / hh * y * Texture2D.height;

                    // get color height
                    var pixel = Texture2D.GetPixel((int) x1, (int) y1);
                    var f = pixel.grayscale; // defines height
                    var g = f * f * f; // some smoothing
                    var s = 0.025f; // some scaling

                    heights[x, y] = g * s;
                }
            }

            data.SetHeights(0, 0, heights);
        }
    }
}

The most interesting thing in this is the smoothing, it dramatically improves the output.

Additionally, you could find which color the pixel is close to from a pre-defined list (e.g. water, grass) and interpolate/smooth.

Also, you might need to adjust the code since I'm not very familiar with TerrainData.