void PaintTexture(){
  td.alphamapResolution = length;
  td.baseMapResolution = length;
  
  float[,,] map = new float[length,length,prototypes.Length];
  for (int x=0;x<length;x++){
   for (int y=0;y<length;y++){
    float tc = texture.GetPixel(x,y).r;
    
    if (tc>max_road){
     map[x,y,1] = 1f;
    }
    if (tc<min_road){
     map[x,y,1] = 1f;
    }
    if (tc<max_road&&tc>min_road){
     map[x,y,0] = 1f;
    }
    if (tc<max_road&&tc>min_road+0.2){
     map[x,y,2] = 1f;
    }
    if (tc>min_road&&tc<min_road+0.05f){
     map[x,y,2] = 1f;
    }

   }
  }    
  td.SetAlphamaps(0,0,map);
  ter.terrainData =td;
    }