There are mirrors in existing video games, why not second life

[JackoThomas]

Grand Theft Auto 5 has stationary mirrors in certain parts of the game - ie. supply stores - where the avatar is mirrored while walking by a mirror. Apparently, much to the chagrin of STA5 players, they are unable to produce the same effect in automobile mirrors while driving. My questions is - if GTA5 can make a mirror where the avatar is moving and picking things up and everything is seen in the mirror as it happens (albeit with a static background), why can't Linden Labs or other people do the same inworld?

[Theresa Tennyson]

5 minutes ago, JackoThomas said:

Grand Theft Auto 5 has stationary mirrors in certain parts of the game - ie. supply stores - where the avatar is mirrored while walking by a mirror. Apparently, much to the chagrin of STA5 players, they are unable to produce the same effect in automobile mirrors while driving. My questions is - if GTA5 can make a mirror where the avatar is moving and picking things up and everything is seen in the mirror as it happens (albeit with a static background), why can't Linden Labs or other people do the same inworld?

Because GTA5 doesn't have to worry about someone intentionally setting up mirrors that reflect each other in a room full of thirty overly-complex avatars dancing around tchotchkes that are designed for close-up static photography.

[Rolig Loon]

People ask that same question many times a year, so you can easily find plenty of discussion in the forums with a simple Google search.  The bottom line is in two parts: 

(1) Unlike MMORGs and almost all other games that you may be familiar with, Second Life does not reside primarily on your computer. Every change that you make, including your own position, is sent to the SL servers and integrated with all other changes continuously.  That puts a very heavy load on the data stream that your viewer and the servers maintain. Adding to it to support reflections would create even more lag than many people see already

(2) creating reflections involves ray tracing, which means a lot of calculations of reflection angles and lines of sight.  Graphics cards in modern desktop computers can handle a lot more of this sort of thing than they could even five years ago, but it's still a heavy load, and it's more than most mid-range computers and most laptops can handle.

Things keep evolving all the time, so there may be a day when LL can make mirrors work, but that day hasn't come yet. They are more trouble than they are worth.

Edited February 27, 2019 by Rolig Loon

[animats]

Few games have mirrors. Here's a list.

Like shadows, mirrors cost you an extra rendering pass. The GPU has to render the scene from the viewpoint of the mirror. Then that image is pasted onto the mirror surface and the scene is rendered again from the avatar's viewpoint. Multiple reflections require extra passes or you get delay and the secondary reflections lag by one or more frame times. Mirrors are not hard to do, they just cost frame rate.

Game designers generally try to keep the number of mirrors, their area, and their resolution down. A single mirror in a room so you can see someone sneaking up behind you, yes. Cities reflected off shiny glass skyscrapers, no. SL, of course, doesn't have control over what users build.

Mirror mode for Firestorm, from 2014.

With enough GPU power, it can work. If the typical SL user had an NVidia 1080 Ti or better, it might be feasible.  The developer Lindens point out that most SL users are running rather low-spec machines. Most users don't have Advanced Lighting Model turned on, let alone shadows.

Edited February 27, 2019 by animats
Period missing.

[ChinRey]

7 hours ago, Rolig Loon said:

(2) creating reflections involves ray tracing, which means a lot of calculations of reflection angles and lines of sight.

There is another way to do it, add a second camera and display the picture from it on a surface MoaP style. I think that's what Animats describes. It's still very render heavy though.