Ever since student project Narbacular Drop was adopted by Valve and spun into seminal puzzle-platformer Portal in 2007, the idea of mind-bending physics in games has captured the imaginations of players and developers alike; games that have followed it such as Antichamber and recent release Manifold Garden demonstrate that there is still unexplored space in the “brain-tickling physics” genre. The question I’ve always asked myself is: how could I create Portal’s portals from scratch?

Image from Portal 2.

This series will explore several complicated concepts: shaders, physics, maths. Portal isn’t the only game to feature portals, of course - the first article will act as a taster and will feature a portal effect similar to classic Spyro - in those games, portals were, visually, just a glimpse at the skybox of another level. Then, we’ll ramp things up and move onto constructing Portal-style portals piece by piece, starting with non-recursive portals seen in games like Manifold Garden and building up to recursion-based portals, as seen in Portal. I’ll do my best to explain each step in full.

The posting schedule for this series is as follows:

As always, there is a GitHub repository for the series. Feel free to poke around while development is ongoing.

Acknowledgements

Assets

This tutorial series uses the following asset packs from various sources: