This one found on some video on Youtube which hasn't seen much circulation by my friend NubSawace, who made a video of it.

Any two surfaces that you are able to make portals on (including nodraw) that are in the same plane and separated by less than 32 units, can cause some problems.

This is demonstrated on all of the official maps in this video.

Trying to put a portal_bumper inside the wall does not fix the problem.

A possible workaround is editing your nodraw texture in your Materials directory so that it is not portable. I can't think of a situation where you would need to put a portal on a nodraw texture (if there are, tell me).

Discuss

...That's messed up.

I'ma test it out right now.

This really doesn't happen on my game at all.

Yeah, try as I might, I can't reproduce it.

Try it at the end of level 13, in the small room at the end.

Turn around and put a portal on the wall that the door is on, against either side wall. then try to put a portal closer to the wall.

Yeah, I was able to reproduce it at the end of level 13 like you suggested. That's some messed up shit indeed.

It only works if you have two surfaces that are portable (nodraw included!) and within 32 units of each other. From what I have seen, Valve uses 16 unit wide walls for walls that have only one textured surface, 16 unit walls where you see a "thin" door (door_model_reference), and 32 units where you see at "thick" door (door_wide_model_reference).

I'm pretty sure that the ones that NubSawace put in the video includes all of the instances on the official map set where this is possible, that he found.

Try to find a wall that is common to two rooms, and go to the room has less of the shared wall, and try this.

To reproduce this on the floor of Testchamber 15, you could do mat_wireframe 1 (So it will show you the border of the portal), then put a portal on the floor with the long side against the glass. Then shoot the other portal in the gap between the portal's wireframe and the base of the glass.

Enjoy!

i found this problem in my map that i'm created that meant you could skip most of a puzzle. I solved it by creating 3 separate brushs, rather than 1 long one. It appears this bug doesn't work over different brushes, but i haven't tested it fully.

You could do that, or move one of your walls by a fraction of a unit (by pressing alt) (or does it round to the nearest unit while rendering?)

Lets face it, portal is full of bugs. All we can really do is point them out so valve can try and fix them.

Yeah that's the goal here. Also I wanted to discuss possibly workarounds for said bugs

portals also can be placed on angled surfaces if the angle is not big.

gepy wrote:
portals also can be placed on angled surfaces if the angle is not big.

how is that a bug? it is needed for flings in the official game

I noticed this glitch one of the first times I played through Portal. In chamber 15, right before the area most people tunnel through, where you are supposed to fling through the second fizzler to redirect the energy ball, you can shoot a portal on one side of the glass wall, then shoot the other, bumping it to the other side of the wall and bypassing the fizzler completely.