Converts a world Y coordinate into a screen Y coordinate based on the current view offset and zoom. When the SetViewOffset is 0,0 and the SetViewZoom is 1.0 world and screen coordinates are the same. For example when the view is offset by 20 pixels down, an object at 0,0 in the world will appear at -20 (off screen) above the screen.
float WorldToScreenY( y )