Changing terrain in real time

Hi, tenix

I'am not sure you mean about update an existing tile by some rules or about navigate on a huge number of tiles, so that below example is about create a tile.

The example is from my similar database, for a 3x3 tile:

 1,3,1325
 1,2,1337
 1,1,1335
 2,3,1325
 2,2,1333
 2,1,1329
 3,3,1326
 3,2,1331
 3,1,1327

With these values retrieved as string (see xyzDb variable), you can use a script like (JS):

 #pragma strict
 var unitsStep : float = 30.0;
 var material : Material;
 private var height : int = 3;
 private var width : int = 3;
 private var area : int = width * height;
 private var vertices = new Vector3[height * width];
 
 var xyzDb="1,3,1325\n1,2,1337\n1,1,1335\n2,3,1325\n2,2,1333\n2,1,1329\n3,3,1326\n3,2,1331\n3,1,1327"; // Records from DB
 var xzyValues = new String[area];
 
 function Start() {
 
     xzyValues = xyzDb.Split(char.Parse("\n"));    
 
     gameObject.AddComponent(MeshCollider);
     gameObject.AddComponent(MeshFilter);
     gameObject.AddComponent(MeshRenderer);
     
     MakeTerrain();
     
 }
 
 function MakeTerrain() {
 
     if (material) {
         renderer.material = material;
     } else {
         renderer.material.color = Color.white;
     }
 
     /// Clean up
     var meshCollider : MeshCollider = gameObject.GetComponent(MeshCollider);
     meshCollider.sharedMesh = null;
     
     var terrain : Mesh = GetComponent(MeshFilter).mesh;
     terrain.Clear();
 
     // Build vertices
     var vertices = new Vector3[height * width];
     var uv = new Vector2[height * width];
 
     var uvScale = Vector2 (1/unitsStep,1/unitsStep);
     
     for (var j : int = 0;  j < xzyValues.Length ;  j++){
         
         var lle=xzyValues[j];
         var xyz=lle.Split(char.Parse(","));    
 
         var x : int = parseInt(xyz[0]);
         var z : int = parseInt(xyz[1]);
         var xx = x * unitsStep;
         var zz = z * unitsStep;
 
         var e : int = parseInt(xyz[2]);
         var vertex = Vector3 (xx, e, zz);
         vertices[j] = vertex;
         uv[j] = Vector2.Scale(Vector2 (xx, zz),uvScale);
 
                                                 
     }
     
     // Assign vertices to terrain
     terrain.vertices = vertices;
     terrain.uv = uv;
 
     // Build triangle indices: 3 indices into vertex array for each triangle
     var triangles = new int[(height - 1) * (width - 1) * 6];
     var index = 0;
     for (z=0;z<height-1;z++)
     {
         for (x=0;x<width-1;x++)
         {
             // For each grid cell output two triangles
             triangles[index++] = (z     * width) + x;
             triangles[index++] = ((z+1) * width) + x;
             triangles[index++] = (z     * width) + x + 1;
             
             triangles[index++] = (z     * width) + x + 1;
             
             triangles[index++] = ((z+1) * width) + x;
             triangles[index++] = ((z+1) * width) + x + 1;
             
             
         }
     }
 
     // And assign them to the terrain
     terrain.triangles = triangles;
         
     // Auto-calculate vertex normals from the terrain
     terrain.RecalculateNormals();
     terrain.RecalculateBounds();
     terrain.Optimize();
     
     // Assign terrain mesh as collider mesh
     meshCollider.sharedMesh = terrain; 
     
 }

Note terrain in the script is not about unity Terrains; I use it for meshes. As suggestion regarding DB, for large areas it's better to you use a NoSQL database, recording for example 1_1 as key and 5 as value, 1_2 as key and 10 and so (exploding by x/z coordinates by "_"). Then, retrieve records in needed range.