New Kama Sutra demos

Just a nomo route demonstration:

map19 -nomo Speed in 0:19.

I don't recall this key grab being mentioned before, but I'm not sure it would be an improvement over the "standard" UV Speed route.

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Nice one, I haven't known this one is also possible. I can see it's not an easy grab.

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Ryback's txt said:
I haven't tested if the demo will play back on Doom2 but it should unless the engine visplane overflows...

Confirmed: OK.

To download, copy/paste the URL. In case anyone has problems, I have put a copy here too.

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Ryback said:


This one makes prboom/prboom-plus pause after 20:31.09 minutes, in both prboom 2.3.1 and prboom-plus 2.4.7.1-test (the latest version), and with complevel 2 (doom2.exe v1.9) specified.

Is anyone else experiencing that problem, or am I just overlooking something obvious?

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My guess is Ryback just paused the game for a few minutes. You can remove the pause with LMPC if you want.

Great run, Ryback! :-) Takes me about the same time to do a normal 100/100 UV run of that map... (yeah, I suck)

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Kristian Ronge said:

My guess is Ryback just paused the game for a few minutes. You can remove the pause with LMPC if you want.

Great run, Ryback! :-) Takes me about the same time to do a normal 100/100 UV run of that map... (yeah, I suck)


Interesting, I didn't even know that was possible. :) I'll try waiting for a bit, then.

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Yeah, there's a three minute pause in there. Forgot all about that.

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Ryback said:

Yeah, there's a three minute pause in there. Forgot all about that.


Oh, OK then - that's good news, since it means I can watch the entire demo after all. ^.^

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Kristian Ronge said:

You can remove the pause with LMPC if you want.

I'm not 100% sure, but I thought there were some possible desync issues if you remove a pause, due to the fact that the gametic number is what determines whether a revenant's missile is homing or non-homing (Donce mentioned this some years back). If it is just a case of odd/even (that's my recollection, albeit hazy), then there is a 50% chance of it being safe to do so.

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Thanks for that PAUSE, I just went to the toilet and made some quick dinner during it.
Great demo all the way, really unexpectable for me!
Ryback: maybe finally Hf23 now?

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Grazza said:
I'm not 100% sure, but I thought there were some possible desync issues if you remove a pause, due to the fact that the gametic number is what determines whether a revenant's missile is homing or non-homing (Donce mentioned this some years back).

You're right. It had slipped my mind... in this case, it's malevolent. Removing the pause desynchs the demo, sadly. :-( Oh well, there's always fast forward.

Gusta -- you know that you can always pause playback if you want to take a break, right?

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Great work, Ryback! You can be sure that I won't beat it this time ;)

Kristian Ronge said:

Gusta -- you know that you can always pause playback if you want to take a break, right?

Oh, really? Thx, I didn't know this...












(Pretty embarassing after years of watching Doom demos.)

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Well, doom.exe and doom2.exe don't allow it, but most (all?) versions of PrBoom and PrBoom-plus do. I assumed that's what Gusta used to watch the run.

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Kristian Ronge said:
Well, doom.exe and doom2.exe don't allow it,

Nor does Boom. Although minimizing the DOS window will lock DOS games until restored (this method has been used by COMPET-N movie recorders to take breaks during long runs).

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Pausing has always been allowed -- or should I say, hasn't been a cause for disqualification -- in the COMPET-N (e.g. 3 pauses for episode and movie runs, see the /admin/compet-X .txts) but Simon preferred that people cut them out. Some of the COMPET-N movie runs do have pauses in them. Simon mentions in a few old .txts that he manually removed a pause here and there.

I've never ever paused while recording, not even to answer the phone. Let it ring. :-)

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Gusta said:

Ryback: maybe finally Hf23 now?

Anyone else want to step in? I know it's possible but I really don't want to do this.

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lol, earlier discussion of methods to pause (or should that be "paws"?). The black cat has since got quieter, but the white one is liable to jump up onto the keyboard without warning.

If it is just a case of odd/even tic number, then it should be possible to remove all but one of the pause tics without causing a desync.

BTW, I think this is related to the issue of desynchs in internal demos - doom(2).exe didn't keep track of the tic numbers too well.

I don't know if Andrey could make it possible to reduce the gamespeed to 0% - that would provide a way to "pause" (set step to 100 to go directly between normal speed and paused) without adding pause tics or risking accidental foul-ups by activating the program again when you don't mean to.

myk said:

... minimizing the DOS window will lock DOS games until restored (this method has been used by COMPET-N movie recorders to take breaks during long runs).

That reminds me of the txt for 30nm4000, where Anders J. gave a running commentary, including what Henning was eating between levels, etc. Before I understood how it was being done, I was wondering where all the pauses were, or that he must be a very fast eater. :)

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Grazza said:
BTW, I think this is related to the issue of desynchs in internal demos - doom(2).exe didn't keep track of the tic numbers too well.

Yeah... yesterday I was playing a PWAD and chose End Game after playing a while and one of the replaced demos it includes (which normally plays back fine) desynched.

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Kristian: I seriously haven't known that I could pause the demo in prboom. That's why I welcomed that Ryback did PAUSE for a while.
heh so thx for the info :-)
Heh,so excellent demo and we discuss just mostly that PAUSE in it :-)

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Gusta said:

I seriously haven't known that I could pause the demo in prboom.

I use pause frequently while watching more or less any interesting demo. It means you take a look at the automap or go walkabout with the walkcam to see what's happening elsewhere (e.g. interesting infights, surprising monster movements) without having to miss any action while 'relocating'. Pausing was also a way to avoid the six-tic jump when changing the gamespeed (especially relevant if watching with slow motion).

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IIRC Anthe's D2S demos had removed pauses in them, but they didn't desync even though they were quite long.

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If it is just a case of odd/even tic number, then it should be possible to remove all but one of the pause tics without causing a desync.

OK, I decided to stop being lazy and try to check this properly.

A relevant(?) snippet from the source code:

(gametic-basetic) & 255;
Based on that, it's modulo 256 - so if you randomly hack pause tics out, there may be no better than a 1 in 256 chance of not affecting the tracer states of any revenant fireballs. However, it means you can safely hack them out in blocks of 256 tics, leaving a pause of at most 255 tics (7.29 seconds).

I tested this with ks286354.lmp, hacking out 7168 tics (tic #43123-50290), leaving a pause of just under a second. The demo duly plays back fine.

So there we are. You can pause for as long as you like, safe in the knowledge that you can later hack out all but a few seconds of it, even in a demo with heavy revenant activity. Assuming, of course, that I haven't missed anything fundamental, which is very possible.

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In the LMPC documentation Girlich mentions the issue posed by Revenants, and also says Arch-viles may somehow cause problems:

You may have difficulties with the play back of such a patched LMP file. This is the case if you patch a LMP file of a level with a revenant (skeleton). The revenant uses a random number generator to choose between a self controlled rocket and a normal rocket. The input of this generator are the last two bits of the game tic number. This means you have to make sure that you cut a number of game tics divisible by 4. In general this is impossible so do not use pause in levels with a revenant. An arch vile makes similar difficulties but I don't even know how to prevent it.

LMPC doesn't have a way to cut off portions of a demo, right? At least I didn't find any commands that did that, although LMPUTIL's got a cut command that lets you specify a range in tics to remove (which I used for this mightily epic demo).

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Interesting. I cut out a further 32 pause tics (leaving just the PS and the PE and a single WT in between), and the demo still played back OK.

The code snippet I quoted was from the saving code (from prboom-plus, though it was marked as by Killough). Whether it was being overly cautious in being modulo 256 rather than modulo 4, or if there is some other reason (to do with archies, or else a formal requirement unrelated to demo sync issues), I don't know. Edit: I think that's for "demo insurance" in MBF demos. So for MBF demos, maybe you can only safely lop them out in multiples of 256; for vanilla demos, I don't see a reason why multiples of 4 shouldn't be safe.

To remove a chunk of tics, I just converted the demo to text with LMPC, and deleted them using Notepad. The tic numbers make this quite easy. (The tic numbers are just comments, so it doesn't matter that they are out of sequence.) A pause takes the form of a PS tic, followed by a bunch of WTs and then a PE.

I presume the "in general this is impossible" comment refers to the fact that it is impossible in general to remove all traces of a pause.

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