The author recently had to write some code to outline 3D objects using OpenGL. The author hunted around the Internet for methods to do this, and eventually came across two main techniques. The first involves the use of Polygon Offsets, and the second involves the use of the Stencil Buffer. This article explains how these two methods work, and explains in a bit more detail what the stencil buffer is.-The author recently had to write some code to outline using OpenGL 3D objects. The author hunted around the Internet for methods to do this, and eventually came across two main techniques. The first involves the use of Polygon Offsets, and the second involves the use of the Stencil Buffer. This article explains how these two methods work, and explains in a bit more detail what the stencil buffer is.