Ever since I played the renowned Portal as a young kid, I was obsessed with the idea of portals and the paradoxes they entail, as well as their ability to transform conventional Euclidean geometry into something much more interesting from a gameplay perspective. For years, I tried to imagine how something that, to a child’s mind, seemed like pure black magic could be implemented.
Image of the system emitting particles in a positive vertical cone with negative vertical acceleration.
My technique is based on using textured planes with a scene capture that mimics the player camera’s movement relative to the entry portal within the local space of the exit portal, creating a “window” illusion. To achieve a seamless transition without interruptions or visual artifacts, I extrude the textured plane as the player enters the transition zone. When the player crosses the original plane, I teleport their position to the exit portal and perform an equivalent extrusion on that portal’s plane, resulting in a clean transition with no perceptible discontinuities.
Below, I show several videos demonstrating the different configurations that can be applied to the portals, both regarding VFX and functionality.
Visual demo.
Color and shape changes.
Portal linking changes.
Portal image distortion configuration.