Valve Emails


Okay. So having noticed that demo playback caused jitters in NPC’s, I sent an email off to Valve with a few questions in it. Here’s the responses I got.--------------------Q1) At some point during Half-Life 2 you altered some code that cause demo playback compatability issues. This caused much frustration in having to downgrade to view and render the demos. Is this going to happen at some point in Episode 1?A1) The current demo protocol is tightly coupled to the network protocol and so is pretty fragile. We have some in-house technology that records at a more abstract level and isn’t bound to the networking. It’s something we’ll roll out at some point in the future and hopefully that will forever get rid of the very issue you mention with the demo version changes being incompatible. No ETA on when that might be yet.Q2) Cl_Interp fixed one of our demo playback issues in the past (Bunny hop jitter) but does it do anything else? Does it have any other use than in demo play back? Does it effect the game play? Why isn’t it set to a lower number by default if these jitters occur in demo play back?A2) The cl_interp setting determines how much interpolation the game does. If you are getting a stead stream of updates (the engine defaults to 20 updates per second) and the interpolation amount is .1 then you should never “run out” of data and the interpolation should be smooth. We chose that number because even if you drop an occasional packet in multiplayer (so the interval between packets looks like you are getting 10 packets per second, or a packet every 0.1 seconds) you should still have smooth play since you have just enough data through which to interpolate.I believe the demo player uses the interpolation amount, cl_interp, to move the camera through it’s path (the camera path is recorded as a separate track into the demo file, and the demo smoothing tools can be used to fix up this path).Q3) When I record a demo in Half-Life 2: Episode 1, NPC’s act VERY jittery and glitchy. Their animations start to skip around and reset to the “standing” position occasionally. It becomes very hard to predict what an NPC is doing, even harder to shoot them/ I tried using cl_interp to see if it was causing it, but it didn’t change anything. Can you shed some light on this? (You can find an example of this here:-…ypass/;5160160)A3) There is a bug we identified internally related to jittery playback of NPCs animations. I’m not 100% sure it’s the same bug. At some point soon, I’ll run your example in the debugger against the fixed code and see if it still has the issue.I’ve forwarded to Martin Otten, who has also worked in this system, to see if he has any further comments on your questions.--------------------So once again, a big thanks to Yahn Bernier/Martin Otten for actually trying to help us with these problems.It’s good to see they actually care about the fan base. :slight_smile:


Nice :)Nice to see VALVe actually talk. You don’t know how much bitching the hl2dm community does.


Maybe ask them why we can’t fly anymore :rolleyes: Well anyway, it’s nice to see that they actually read questions from their gamers and not just send an automated response.


We know why we can’t. Because they make it so we cannot. Eh?


If hl2ep1:dq will be released before episode2, then in episode2 they will remove barrel wallclimbing and other remaining tricks =)



They will never take away ramp jumps and the strafe jump. They’ve been here for 10 years now :smiley:


you guys still trying to speedrun it? :o




… I would partisipate a LOT more, just I find it quite useless finding routes and that, when I cannot record them or maybe in the long run, get credit for them.


Something tells me VALVe will never fix it. Oh well…