Question

I decided to make a isometric game using c++ and cocos2d-x.
Each isometric tile has an X and an Y coordinate, incresing 1 per tile moved. This is how I am converting tile to screen coordinates.

cocos2d::CCPoint WorldPos::convertToScreen(){
    cocos2d::CCPoint posScreen;; 
    posScreen.x=(this->x)*(TILE_WIDTH/2) + (this->y)*-TILE_HEIGHT;
    posScreen.y=(this->x)*(TILE_HEIGHT/2) + (this->y)*(TILE_HEIGHT/2);

    return posScreen;
}

The tiles are all 40px wide and 20px tall.

now I need a function to convert these world coordinates (the isometric coordinates) back to screen coordinates. something like

WorldPos* WorldPos::convertToWorld(cocos2d::CCPoint &point)

I can’t seem to figure this one out, am I doing it all wrong and should I do positioning is a diffirent way or is there some kind of calculation that I can’t figure out?

Answer 1

Try:

WorldPos WorldPos::convertToWorld(cocos2d::CCPoint &point) {
  int x = (point.x + 2*point.y)/40;
  int y = (2*point.y - point.x)/40;
  return WorldPos(x, y);
}

Logic:

Px = 20*Wx - 20*Wy
Py = 10*Wx + 10*Wy, thus

Px + 2*Py = 40*Wx -> Wx = (Px + 2*Py) / 40
Px - 2*Py = -40*Wy -> Wy = (2*Py - Px) / 40

where Px, Py, Wx, Wy are CCpoint::x, CCPoint::y, WorldPos::x, WorldPos.y, respectively