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Realtime?

category: general [glöplog]
When people try to explain what demos are to outsiders, they often say that the special thing about demos is that they are "realtime", which distinguishes them from pre-rendered animations. Alas, many demos also feature precalculation! So how does this go together? Wouldn't it be more honest to say that demos originated in the home computers of the 1980s, where CPU power and memory were limited and therefore computer animations could be generated only by relatively small and efficient programs? And that modern demos stand in this tradition?
added on the 2016-06-18 14:02:10 by Adok Adok
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added on the 2016-06-18 14:11:43 by w00t! w00t!
I understand it could sound confuzing.
I would say, that pure animation in a demo is not realtime. Its just a sequence of images shown.
But when it comes to the term "realtime" about animations, we could here deal with a kind of decompression algorithm or so, that is a realtime-effect in itself.
On small limited computers, it is a classic problem to show an animation, so clever tricks were needed for that.

Another thing about that:
Often, demomaking is the same as being an illusionist. You make an illusion to show something "impossible" on a machine configuration.
When an illusionist makes a card trick, he hides the cards in his sleeve. Its an old trick that most can figure out. But what if the illusionist just wears a tshirt? You can't hide much in that sleeve.. so there this old trick is no longer simple, since there is no much sleeve.. The trick is the same, but is has harder limits - and that limit is a new trick itself now.
added on the 2016-06-18 15:00:30 by gfbtm gfbtm
Pre-calculation does not mean that full-size scene images are pre-rendered - only fragments of the scene like textures, paths and look-up tables. Most of it is still assembled, transformed and rendered in realtime. The geometry/data (all components that make the scene) is there (in memory) which is a big difference compared to videos. Modern demos are more like non-interactive video games and I always use this explanation for outsiders.

@w00t!: try 4chan
added on the 2016-06-18 15:06:40 by movAX13h movAX13h
just say it's magic and that you have joined a cult.
added on the 2016-06-18 15:23:17 by 1in10 1in10
i like the cult explanation
added on the 2016-06-18 15:28:24 by blackpawn blackpawn
please stare at this hypno glow bouncing cube and enjoy some of our special kool-aid XD
added on the 2016-06-18 15:34:34 by blackpawn blackpawn
interesting how you write in third person. ever explained it to somebody yourself? I always described it as realtime. "it's not a video, it is calculated right now". precalc doesn't matter. the illumination and assembly of the graphics is computed in realtime. and i could show them the difference in cpu and gpu utilisation when running a video and a demo. the size component - if you wanna go explain there - doesn't matter for demos. some are bigger then a solid compressed video counterpart. and... the core of byte sizes below a jpg is what the peops don't get. how procedural works, is what you don't explain to regular people that have no prior experience with some form of creation of artwork, and are used to believe that everything they see is photographed, photoshopped, painted or somehow modelled in shape and burned into a video. to show them that is using a jpg and running an intro. they don't get the size part tho. usually too dumb to imagine.
added on the 2016-06-18 15:45:46 by yumeji yumeji
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usually too dumb to imagine.

or they just get bored after the first 15 minutes of your talk about size utilisation video components jpg core bytes

but to the point.
why so evangelical?
why the forced preaching of the wonders of demos?

let people be.

not everyone is interested of finger painting.
not matter how many finger you stuck up their ass..
added on the 2016-06-18 16:04:02 by 1in10 1in10
The usual advantage of real-time demo tools is that you can get production-ready preview instantly, unlike in typical CG short/movie production when you have to wait 1 hour for the frame to render and usually still not a final quality with all post-fx etc... So it's not only about interaction, you have much more practical applications if you can render quality non-interactive animations in real-time = scalable resolution, multiple projectors, sometimes more FPS (but not necessarily), real-time inputs (i.e. video streams, which is kind of interaction actually), shorter production cycle etc..
If all of this is present in demos? Not really, but truly real-time demo and/or demo tool would have this features/qualities, unlike compressed videos/images.
added on the 2016-06-18 16:04:26 by tomkh tomkh
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let people be.

You are assuming they want to explain the concept to people who are not interested.
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You are assuming they want to explain the concept to people who are not interested.

only way to make it funny.

if you want to explain something to people use words and concepts that they know.
added on the 2016-06-18 16:21:10 by 1in10 1in10
"it's not video but the same tech as in video games!"
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"it's not video but the same tech as in video games!"


yes. an instead of made by 100 or so team is usually made by 1 to 3 people.
also looks and sounds better.
added on the 2016-06-18 16:24:27 by 1in10 1in10
and you're in it for the cocaine, not the money!
but you can stop anytime you want. really.
added on the 2016-06-18 16:41:53 by 1in10 1in10
Just say that is about create images with code and music with numbers.
Perhaps they will understand... even before you start showing demos to them.

In reality, it's black magic.
added on the 2016-06-18 18:01:33 by ham ham
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it's black magic.

there is no black or white magic just energy and your own preference to do good or bad.
added on the 2016-06-18 18:24:33 by 1in10 1in10
"he home computers of the 1980s, where CPU power and memory were limited and therefore computer animations could be generated only by relatively small and efficient programs?"

what ?! on a typical 8 bit home pc even an animation is a big feat, since memory and I/O speed is very limited. they dont have the horsepower to stream, and there's hardly horsepower to depack pre rendered stuff too, but even if you can its maximum a few dozen frames.

and an animation is NOT realtime, so it doesnt exactly needs efficient programs.


precalc was always accepted in the scene, if you have tables to speed up multiplication that is very far away from an animation.
added on the 2016-06-18 22:43:44 by Oswald Oswald
"when people try to explain what demos are to outsiders" ?

..people do that?
added on the 2016-06-18 23:32:22 by farfar farfar
it's not a technical feat - it's a cultural artifact of an obscure subculture - duh. Anybody who understand anthropology will tell you that much.
added on the 2016-06-19 02:57:50 by Czery Czery
It's not a very good explanation. A better one would be, demos are computer programs that show visuals and play sounds which are supposed to impress the audience.
added on the 2016-06-19 08:56:32 by yzi yzi
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"when people try to explain what demos are to outsiders" ?


I used to do that back in 1999-200x, since I thought demoscene is like the 2nd coming of christ. I was so obsessed, speaking to people who clearly didn't care about, and clearly continued listening out of politeness. It was a form of mania.

Then I got bored :)
added on the 2016-06-19 12:02:42 by Optimonk Optimonk
I tend to create more and more videos from my codebase. Having the effects running in realtime still gives me some kind of satisfaction and improves the editing/direction phase.

I mostly prefer the format due to the huge array of tools we can apply make graphics. I also like all the small puzzles :)
added on the 2016-06-19 12:44:11 by quisten quisten
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"when people try to explain what demos are to outsiders" ?

..people do that?


Regular occurrence in my house when people come over. Thankfully they are usually gamers so when I show them 64k exe and what it does they tend to get it.
added on the 2016-06-19 13:26:02 by djh0ffman djh0ffman

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