anchor.diff:  
     if fUseVBO then
     begin
  -    if Length(fTilesVtx) = 0 then Exit; //Nothing to render
  +    if fTilesVtxCount = 0 then Exit; //Nothing to render
       BindVBOArray(vatTile);
       //Setup vertex and UV layout and offsets
       glEnableClientState(GL_VERTEX_ARRAY);
  
positive.code:     glTexCoordPointer(2, GL_FLOAT, SizeOf(TTileVerticeExt), Pointer(12));
  
      //Here and above OGL requests Pointer, but in fact it's just a number (offset within Array)
      glDrawElements(GL_TRIANGLES, Length(fTilesInd), GL_UNSIGNED_INT, Pointer(0));
  
      glDisableClientState(GL_VERTEX_ARRAY);
      glDisableClientState(GL_TEXTURE_COORD_ARRAY);
  
negative.code: 
  const
    TILE_LAYERS_USE_VBO = False;
    MAX_RENDERABLE_TILES = (MAX_MAP_SIZE + 1) * (MAX_MAP_SIZE + 1);
    MAX_RENDERABLE_VERTICIES = 4 * MAX_RENDERABLE_TILES;
    MAX_RENDERABLE_INDEXES = 6 * MAX_RENDERABLE_TILES;
  
  
  constructor TRenderTerrain.Create;
  