In my Xna game, I am trying to have my playfield scale to the screen that it is running on. To do this, I use proportions to find the percent that the real window is scaled rela
try this float _percent = _realViewport.Width * 1.0/ (float)this._viewport.Width;
,by adding multiplication by 1.0, the integer will automatically convert to float.
Because integer division truncates (XNA's Viewport type has integer width and height properties), and 640 / 1280 is 0.5, which truncates to zero.
Cast one of your values to a float if you want floating point division:
float _percent = _realViewport.Width / (float)this._viewport.Width;