Portal Placement Tricks
Overview
Portal 2 has several techniques for placing portals in ways not intended by the developers. These tricks can create shortcuts by reaching portalable surfaces early, or even creating portals on surfaces not intended to support them. This page describes each trick, explains the trick's execution and mechanics, and lists currently-known places where that trick can be used in routing.
Portal Bumping
Portal bumping is an intended mechanic with some unintended uses. When a player has an existing portal on a surface and shoots their other portal at the same location, rather than replacing the existing portal or allowing both portals to overlap, the game will reposition (or "bump") the second portal to the closest available space on that portable surface, if such a space exists.
When portal bumping, the new portal will be bumped away from the centre of the existing portal, based on where you aimed the new portal. E.g. if you shoot to the left of the existing portal's centre, the new portal will be bumped to the left (assuming there is space available in that direction). If you aim above the existing portal's centre, the new portal will be bumped upwards etc.
Portal bumping works in both single player and cooperative, but you can only portal bump off of your own portals (if you try to portal bump off another player's portal, you will normally replace their portal instead).
Execution of Trick
Video 2.1.A - Portal 1 and Portal 2 portal bumps by MrCatMcFly (Portal 2 section starts at 4:25).
Portal bumping can be exploited as it ignores some checks when placing the new portal. Firstly, the portal can only be bumped a short distance, but this is enough to cross thin obstacles, and the game does not check if there are any obstacles between the existing portal and new portal. This can easily be seen in Turret Sabotage, where a beginner route involves firing a portal beside the door where Wheatley breaks the glass, then bumping the other portal past the door instead of waiting for Wheatley's actions to finish. This is demonstrated in Video 2.1.A at around the 4:40 mark.
Video 2.1.B - Bridge Fling OoB portal bump by unity & RealCreative (first orange portal at 2 seconds, easy to miss without playing in slow motion).
Portals can sometimes be bumped out of bounds ("OoB") as well. One example of this is in Bridge Fling, which is demonstrated in Video 2.1.B at around the 2 second mark.
Video 2.1.C - Laser Platform portal bump by swagatron (happens at 5 seconds, easy to miss without playing in slow motion).
Secondly, portals can be bumped onto a portalable surface that is normally too small to support a portal. This can be used in Laser Platform to place a portal slightly nearer the player early in the chamber, saving a fraction of a second (as in Video 2.1.C).
Uses of Trick
Single Player, Speedrun:
- Turret Sabotage (suboptimal but beginner-friendly route)
- Laser Platform
Cooperative, Speedrun:
Miscellaneous:
- Various observation rooms can be portal bumped into if there is a portable ceiling outside of them (e.g. in Turret Intro)