In the lesson about rotating a box, how do you work out how far to move the vanishing points? Is there a way of calculating it, or is it just done by eye?
By making a new layer and creating a giant L, the 90 degree angle will help measure out the distance from one point to the other as vanishing points slide over. Many traditional artists use drawing triangles, but it can be done with a book, or any object with a 90 degree angle.
