After a lot of days of silence, let's start again the APOCALYX 3D Engine daily posts. Today just a short old news: I simply signal an old paper of mine that describes how to simulate a refractive (and reflective) perfect sphere with just two triangles.
In DemoPack1 is available a demo (RefractiveSphere.lua) about the subject.
The article dates back to 2004, so it explains how to simulate a sphere through fragment programs. Now the same effect can be accomplished much more easily using fragment shaders and the GLSL language, but the theory behind the scene is still interesting.
Download the paper from here: RefractiveSphere.pdf.