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Jekyll Grim Payne

Classic Doom 'squeeze between pillars' bug + question about rocketjumping

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So I was trying to practice speedrunning skills a little and I watched some speedruns and everybody seems to be using this squeezing bug when something goes wrong with Player Thing collision, and the player gets in a narrow passage. A classic example is Doom2 Map 16 where speedrunners skip the red key and just sqeeze between the pillar and the wall.

The thing is, I don't quite understand it. Does it work only in original Doom? I tried it in ZDoom and in PRBoom and PRBoom+ and neither of those let me do it. Or perhaps I was doing something wrong?

Weirdly I couldn't find any information on Google although this seems to be a classic and common bug. Perhaps I didn't know its proper name. Anyway, I'd appreciate some information on how this works.



And my other question is about classic rocket-jumping. HOW THE HELL does it work? There are no guides or any information out there, and what speedrunners do seems like pure magic (because I don't see any correlation between the direction they run to, the direction they shoot and the place where they end up after the jump) and I don't get how to do it at all. Perhaps there IS a guide out there somewhere?

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It's called "gliding", and it is possible to do in ports like PrBoom-plus and ZDoom too, but it's difficult - you need to position yourself exactly precisely, including the angle, and perhaps keep trying for some time.

Rocket jumping works this way: At the very moment when a rocket hits a wall or an obstacle, it explodes and causes radius damage, as well as horizontal thrust. If the player is close to the center of the explosion, it will thrust him strongly. It will always thrust him in the direction away from the center of the explosion. If he already runs roughly in that direction, he will gain even greater speed. Speedrunners are able to time it well for maximum efficiency.

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scifista42 said:

It's called "gliding", and it is possible to do in ports like PrBoom-plus and ZDoom too, but it's difficult - you need to position yourself exactly precisely, including the angle, and perhaps keep trying for some time.


Thaaat's what it's called... OK, thanks

scifista42 said:

Rocket jumping works this way: At the very moment when a rocket hits a wall or an obstacle, it explodes and causes radius damage, as well as horizontal thrust. If the player is close to the center of the explosion, it will thrust him strongly. It will always thrust him in the direction away from the center of the explosion. If he already runs roughly in that direction, he will gain even greater speed. Speedrunners are able to time it well for maximum efficiency.


Obviously I know what rocket jumping is and how it works, I don't need the theory. What I'm saying is I absolutely don't see how they do it the way they do it. It looks very weird and sometimes even the direction the player is propelled seems very strange. That's why I'm asking about guides or stuff like this, becaue to pull it off the way speedrunners pull it off on Dead Simple I really need some instructions.

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Jekyll Grim Payne said:

It looks very weird and sometimes even the direction the player is propelled seems very strange.

The trick is that a (strafe-)running player normally moves faster than a rocket. If he fires a rocket into a wall at close distance, then before the rocket actually hits the wall and explodes, he can manage to make a step forward, which positions him to the optimal place to get maximum effect of the thrust.

It's all about exact positioning and timing, and it's hard. Instead of looking up instructions, you might need practice to do that. I personally can't and don't do it, as I'm not a speedrunner.

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scifista42 said:

The trick is that a (strafe-)running player normally moves faster than a rocket. If he fires a rocket into a wall at close distance, then before the rocket actually hits the wall and explodes, he can manage to make a step forward, which positions him to the optimal place to get maximum effect of the thrust.


Well, I know about strafe-running too of course :) But still... For now neither rocket-jumping nor gliding seem to work for me. Thanks anyway.

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I can explain how to do the glide on map16 in prboom-plus. It's not hard at all, you just need to know what to do.

First of all, you should do it while recording a demo because in that case mouse turning is limited, so you can find the needed angle easier. Alternatively, use the -shorttics parameter to enable that limitation.

Stand in front of the red bar like this. Find an angle where running forward doesn't seem to move you almost at all. There still will be a very slight movement because in vanilla you don't move exactly forward while pressing "forward", there is also a slight movement to the side.

Now also strafe to the left as far as possible until you feel that you touched the wall. Now enable minimal vertical mouse movement in the options and try moving the mouse forward very carefully. Maybe not immediately but sooner or later you should succeed. If you don't seem to go through, stop for a moment then start trying again, etc.

You can use pretty much the same method for all glides where you have a wall to align yourself to (they are called guided glides). There are also guideless glides where you don't have anything like that and you have to find the necessary position all by yourself: here I can't help you because I never managed to do such a glide.


Regarding rocket jumping, it would be nice to see some of your attempts so we could tell what you're doing wrong. The map07 rocket jump is imo very very hard, even world record speedrunners have troubles with it. So maybe you should practice on something easier first. I agree the Map07 jump looks strange, it's hard to believe that it works. :)

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DMGUYDZ64 said:

The rocket jumping didn't really exist till Sourceports that allowed freelook appeared .


No freelooking

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40oz said:

No freelooking

Control is limited though, Also .. You can't do it without autoaim (No monsters), That video really Shows how silly is RocketJumping =3 .

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@DMGUYDZ64: It's a difficult-to-master but useful vanilla speedrunning trick, and that's how you should take it, your reply comes off as ignorant to that.

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DMGUYDZ64 said:

Control is limited though, Also .. You can't do it without autoaim (No monsters), That video really Shows how silly is RocketJumping =3 .


In vanilla, the trick has nothing to do with autoaim, and it is possible in nomonsters if you perform it off a pillar.

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DOOM 2 SETUPS (pictures)

Map 07 rocket jump: http://i.imgur.com/dhYtStR.png
This is the angle you want while standing in the corner.

http://i.imgur.com/5AIk5cu.png
This position will get you to the exit platform (move directly left from the first screenshot). sr50 left and do the rj. Both the rocket at the far left of the image and the very tail end of the rocket launcher work as visual cues.

Map 14 rocket jump:
Slide along the wall to get to this position: http://i.imgur.com/mGi5gcj.png (it’s pretty lenient)
Turn in place to this angle: http://i.imgur.com/rAv8rof.png
Sr50 left, do the rocket jump, let go of forward once you’re in the air so you don’t slide off the landing platform.

Should atleast give you an idea that the setups are quite specific for these RJ's, doing them randomly without knowledge is extremely difficult.

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DMGUYDZ64 said:

The rocket jumping didn't really exist till Sourceports that allowed freelook appeared .

It goes all back to E3M6, where the secret exit was even designed for it.

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I swear I've done E3M6's secret without rocket jumping. When I played on Playstation I Strafe-Runned into it.

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Hoodie said:

I swear I've done E3M6's secret without rocket jumping. When I played on Playstation I Strafe-Runned into it.

The Jaguar version of this level doesn't have a secret exit here, so you must be thinking of something else. SNES maybe? I believe in that port, the level is modified in such a way to make the rocket jump unnecessary (you can just literally run off the platform).

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It would be more clear if we used different terms for using an explosion to accelerate horizontally vs. using it to climb vertically. Such as "rocket boosting" vs "rocket climbing". Doom doesn't feature rocket climbing unless you have a port with mouselook, but there are plenty of vanilla-compatible tricks where you use rocket boosting.

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Doom doesn't feature rocket climbing unless you have a port with mouselook, but there are plenty of vanilla-compatible tricks where you use rocket boosting.

Even if it did have mouselook, I'm under the impression that splash damage cannot thrust actors vertically in Vanilla.

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Wagi said:

Even if it did have mouselook, I'm under the impression that splash damage cannot thrust actors vertically in Vanilla.


Only as part of the Archvile's attack.

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Wagi said:

Even if it did have mouselook, I'm under the impression that splash damage cannot thrust actors vertically in Vanilla.

Correct. The point is: Ports that support mouselook usually also support finitely tall actors and taking Z coordinate into account when doing splash damage. ;)

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I actually discovered the original MAP16 glide using ZDoom. At first I figured it was probably a ZDoom-specific engine bug, but then discovered I could do it in vanilla as well, and the rest is history.

Rocket jumping is so-named because a "jump" in Doom parlance, at least in vanilla speedrunning, has always referred to running off one edge and landing on another. Doing so with a speed assist from a rocket allows you to travel across larger gaps, and is therefore termed a rocket jump. Speed assists from strafe-50 movement are strafe-50 jumps. The existence of Arch Vile jumps muddies the water a little, but basically, in Doom speedrunning, "jump" in no way implies vertical movement.

I guess maybe it's a bit misleading if you're mainly familiar with rocket jumping in other games with vertical jumping and damage boosts. "Rocket boosting" or "rocket pushing" might be a little more descriptive of how it works in Doom. But amongst speedrunners its meaning is well understood, and personally I think it's a nice link to the legendary Quake speedrunning scene, which was a huge inspiration for many runners.

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DMGUYDZ64 said:

The rocket jumping didn't really exist till Sourceports that allowed freelook appeared .

I feel like you've never watched rocket jumping in any game before; even outside of games where the player's ability ascend is completely tied to the level allowing them to, there's still plenty of rocket jumps that feature minimal vertical movement and instead focus on how far an explosion can send the player forward.

Heck, that's a primary purpose of advanced rocket jumps in TF2; not blasting yourself up, but covering the most amount of horizontal space in the least amount of time ( and rockets ) possible.

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4shockblast said:

In vanilla, the trick has nothing to do with autoaim, and it is possible in nomonsters if you perform it off a pillar.

Whenever i think of Rocket jumping , i think of super skills, imagine how stupid will it look like if the New DOOM had rocket jumping , all we're going to see is players flying arround the level .

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Hoodie said:

I swear I've done E3M6's secret without rocket jumping. When I played on Playstation I Strafe-Runned into it.

As stated in the wiki article, you can also straferun in vanilla, or glitch the "action" traversal through the wall to press the switch.  I believe each method was used at least once in COMPET-N.

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In PC Doom/Ultimate Doom, as well the later console ports that use the original maps, you can strafe-run into the E3M6 box; or rocket-jump into it; or activate the switch from outside.

In the console ports based on the Jaguar Doom mapset (3DO, PS1, GBA), you do none of that because the layout is pretty different. There's no section of the level with a box to jump into and there's no secret exit.

In the SNES version, you simply run into it since the map structure was changed to accommodate the fact that there's no rocket jumping and (I think) strafe-running.

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