I have a test for that xD
32 Seconds with portals 3 bounces max/min branched pathtracing
32 Seconds with no portals 3 bounces max/min branched pathtracing
This patch is looking pretty promising so far (from the looks of the images), and in a sense may bring far more significant performance increases for indoor scenes compared to the adaptive sampling patch.
One question though, and I don’t know how possible it is, but would it be possible to have an ‘influence’ slider for the portal object which controls its overall importance to sampling? The reason I ask is because if this was done, it would allow for the use of portals in images that also have a modeled outdoor component (beyond the windows that the portal covers)
In general, lowering the importance would decrease the convergence rate in the indoor part, but would allow at least a few samples for the outdoor part (which is okay because it would need a lot less samples to converge). Do you think it could be done, because if so, the usefulness of the patch would skyrocket.
F**ck, this looks like porn in my eyes :eek:
here have the clean render 
~5 min render 2 GTX 970s but it would have been hours without the portals thanks @lukasstockner97
I need a Macbuild of this!
Thanx Odin!
Sorry, I have no Mac here 
If anyone could build the patch for Mac, that would be awesome!
LordOdin: Wow, these comparisons are great, thanks! As for the worst-case render: I suppose you used multiple tiny portals? If yes, does it help to cover all the holes with a single portal? Using many portals totally kills the samples/sec.
Here’s a scene which renders worse with portal than without it. Seems quite weird and I suspect it’s the HDR with high values. https://dl.dropboxusercontent.com/u/59804993/portal.blend
It was 1 portal 
This is great! Been hoping for a patch like this for a while to come along. Lukas, i would like to thank you for your continued development of cycles!
From playing with the light portals it feels like a bigger portal relative to the scene is less efficient… now it is only a feeling not a fact lol
Lucas are the portals related to metropolis ?
No, they’re completely different things.
GOOD but any blend file for the setup?
Here is my scene http://theorysend.com/view/9c6afc78e695d616687a881a86c4d84ab221249d
:edit:
Forgot to mention it doesnt have the HDRI because licensing and stuff you know how it is lol
just google the name of the hdri its looking for you will find it lol
Wow fantastic! I hope this makes its way into trunk!
i cant wait to see this in trunk!
How long I have been waiting for this! Thank you very much! 
Here is the bug with portal when used with other lamps (even if they emit zero light, the sun is even disconnected from lamp output in the nodes)
With sun power zero + portal: (darker render and “border” on the window wall)
Without sun (unchecked visibility and render from outliner)
can someone explain to me how the portal light should be placed ?.
Because i have scene in when i enable it the light disapears, i think i do something wrong.
- may the light fall in from an angle trough a window ?