Animating 3D object using Mask layer

Some perspective drawing knowledge is required in order to understand the following tutorial.

Step 1

Select the line tool, press shift and draw a horizontal line along the length of the page. Then choose modify>align>horizontal>align to page and press OK. This line will represent our horizon. With the line tool selected, press shift and draw a vertical line across the center of our horizon and along the height of the page. The point where the two lines intersect will be our vanishing point. Now double-click on the layer's name and name it Guides. Lock the layer.
See picture: