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Scene capture 2d and performance issues

So I’m relatively new to UE4, and one of the priority tasks I have right now is to render portals which I’ve achieved using scene capture 2d, render textures and math. The performance hit is massive though, for just two portals (and I will likely need to use more). I have a moderate sized open world with what at present is a single dynamic light source. Reducing render texture size helps only slightly, reducing the draw distance of the scene capture cameras barely does anything to help… any ideas on how to get this working in real time with interactive framerates?

Going to bump this because I have a similar problem. I can set mine up for portals but on a new Mac that has no other problems in game the hit to performance is just too much. I’ve restricted the capture moments to when the portal is in view and when the player is in front of it but still, it doesn’t improve. On my pc with a strong gpu,there is no problem.

Why is this so resource heavy, and is there another solution for a portal type of Pane render?

I don’t know much about what you need to ‘see’ to visually sell the effect in an open world scenario portal, but scene capture has ‘flags’ you can check or uncheck, for instance remove AA, fog, shadows make it low res etc… that could help reduce the cost.
I think if it has an additive effect over the image such as distort and other fx you can probably get away with even lower resolutions and lesser flags.

There’s a couple of free portal projects floating around the forums iirc, take a look…
See how they did it to see if rendering quality is decreased when not close up etc.
When you can’t lower the render quality, lowering the frame rate may be an option…
Scene capture in every engine tends to put a big load on the scene, so experiment…

Like others have said, make sure to find as many ways to lighten the load. The update rate would probably be more than fine at something like 15-20fps (~0.07 to 0.05s). You could even make the portals have a BP timer function that checks 5-10 times per second for the dot product between the player and the portal and then use that to dictate whether or not it it decides to update. There’s no point in updating it if it’s not visible. You could also use distance to modify the update rate and that dot product as well. There are a ton of ways you can pinch more performance out of it and keep it from ticking constantly.