Draw3dSprite was declaring new instance variables, fixed to use local va...

...riables

The variables _sprw, _sprh, _cx, and _cy were declared as local variables but were never assigned to or called. Instead, new instance variables were created with similar names: sprw, sprh, cx, and cy. I fixed this so that the local variables were used instead (_sprw, _sprh, _cx, and _cy).