Question by ohunity · Sep 25, 2019 at 08:48 PM · c#terrain normals terraindata normalmap

Bake terrain normal via script

I am Interested in exporting my Unity terrain height data into a normal map via script within Unity, I not a programmer, so this is pretty much black magic to me, but I am not 100% useless.

This is a free script I have laying around which does exactly what I want, however it is intended for mesh terrain.

 protected override void CreateMap(float[] heights, int width, int height)
         {
 
             float ux = 1.0f / (width - 1.0f);
             float uy = 1.0f / (height - 1.0f);
 
             float scaleX = m_terrainHeight / m_terrainWidth;
             float scaleY = m_terrainHeight / m_terrainLength;
 
             Texture2D normalMap = new Texture2D(width, height, TextureFormat.ARGB32, false, true);
 
             for (int y = 0; y < height; y++)
             {
                 for (int x = 0; x < width; x++)
                 {
 
                     int xp1 = (x == width - 1) ? x : x + 1;
                     int xn1 = (x == 0) ? x : x - 1;
 
                     int yp1 = (y == height - 1) ? y : y + 1;
                     int yn1 = (y == 0) ? y : y - 1;
 
                     float l = heights[xn1 + y * width] * scaleX;
                     float r = heights[xp1 + y * width] * scaleX;
 
                     float b = heights[x + yn1 * width] * scaleY;
                     float t = heights[x + yp1 * width] * scaleY;
 
                     float dx = (r - l) / (2.0f * ux);
                     float dy = (t - b) / (2.0f * uy);
 
                     Vector3 normal;
                     normal.x = -dx;
                     normal.y = -dy; //you might need to flip y
                     normal.z = 1;
                     normal.Normalize();
 
                     Color pixel;
                     pixel.r = normal.x * 0.5f + 0.5f;
                     pixel.g = normal.y * 0.5f + 0.5f;
                     pixel.b = normal.z;
                     pixel.a = 1.0f;
 
                     normalMap.SetPixel(x, y, pixel);
                 }
 
             }
 
             normalMap.Apply();
             m_material.mainTexture = normalMap;
         }
 
     }

I believe the key height data here is "heights" which is a float array from the heightmap on the mesh terrain, here is what the above script derives from.

 void Start()
         {
 
             if (m_material == null) return;
 
             string fileName = Application.dataPath + "/TerrainTopology/Heights.raw";
             float[] heights = Load16Bit(fileName);
 
             int width = 1024;
             int height = 1024;
 
             CreateMap(heights, width, height);
         }
 
         void OnDestroy()
         {
             if (m_material == null) return;
             m_material.mainTexture = null;
         }
 
         protected abstract void CreateMap(float[] heights, int width, int height);
 
         protected float[] Load16Bit(string fileName, bool bigendian = false)
         {
             byte[] bytes = System.IO.File.ReadAllBytes(fileName);
 
             int size = bytes.Length / 2;
             float[] data = new float[size];
 
             for (int x = 0, i = 0; x < size; x++)
             {
                 data[x] = (bigendian) ? (bytes[i++] * 256.0f + bytes[i++]) : (bytes[i++] + bytes[i++] * 256.0f);
                 data[x] /= ushort.MaxValue;
             }
 
             return data;

So, I am wondering if anyone knows how this could be converted to take the heightmap from a Unity Terrain instead of a mesh terrain. I assumed I would be able to do something like, heights = myTerrain.terrainData.GetHeights; However that is a nested [,] float, which I have no clue how to make work with the above set up.

Worth noting the only goal here is to do it within Unity via script using a similar method to the above, I am aware I could export the heightmap to a third party program and generate it there.

Any tips from you programming experts would be amazingly helpful!!

Thanks in advance

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