Creating a texture from tileset

Unity Engine
1

Hi, I have been working on a system that creates a texture for a platform by sampling different tiles from a single tileset. I have managed to get it working but the problem is that its very very slow. Just wandering if anyone has any ideas how I could speed things up or if there is any other approaches i should be looking into, thanks in advance.

void Generate () {
     
     tileSize = texture.width / 4;
     
     genTexture = new Texture2D(tileSize * (_sizeX + 1), tileSize * (_sizeY + 1));
     
     for (int y = 0; y < _sizeY+1; y++) {
       for (int x = 0; x < _sizeX+1; x++) {
         
         int sourcePositionX = 0;
         int sourcePositionY = 0;
         
         //get source position
         
         //single
         if (_sizeX == 0 && _sizeY == 0) {
           sourcePositionX = 3;
           sourcePositionY = 3;
         }
         
         //block
         if (_sizeX > 0 && _sizeY > 0) {
           if (x == 0) {
             sourcePositionX = 0;
           } else if (x > 0 && x < _sizeX) {
             sourcePositionX = 1;
           } else if (x == _sizeX) {
             sourcePositionX = 2;
           }
           
           if (y == 0) {
             sourcePositionY = 0;
           } else if (y > 0 && y < _sizeY) {
             sourcePositionY = 1;
           } else if (y == _sizeY) {
             sourcePositionY = 2;
           }
         }
         
         //long
         if (sizeX > 0 && _sizeY == 0) {
           sourcePositionY = 3;
           
           if (x == 0) {
             sourcePositionX = 0;
           } else if (x > 0 && x < _sizeX) {
             sourcePositionX = 1;
           } else if (x == _sizeX) {
             sourcePositionX = 2;
           }
         }
         
         //tall
         if (sizeY > 0 && _sizeX == 0) {
           sourcePositionX = 3;
           
           if (y == 0) {
             sourcePositionY = 0;
           } else if (y > 0 && y < _sizeY) {
             sourcePositionY = 1;
           } else if (y == _sizeY) {
             sourcePositionY = 2;
           }
         }
         
         //copy over data from source
         Color[] pixelData = texture.GetPixels (sourcePositionX * tileSize, sourcePositionY * tileSize, tileSize, tileSize, 0);
         genTexture.SetPixels (x * tileSize, y * tileSize, tileSize, tileSize, pixelData);

         //adjust scale
         transform.localScale = new Vector3(2f, 2f);
       }
     }
     
     //create sprite from texture
     genTexture.Apply ();
     Sprite sprite = Sprite.Create (genTexture, new Rect(0, 0, genTexture.width, genTexture.height), new Vector2(0, 1));
     spriteRenderer.sprite = sprite;

     //set collision box
     collider.size = new Vector2(sprite.bounds.size.x, sprite.bounds.size.y);
     collider.center = new Vector2(sprite.bounds.center.x, sprite.bounds.center.y);
   }
2

texture.Apply() is very expensive. Are you calling the function Generate() a lot?

3

its called every time the size changes which is controled by user input.