Guide to Prince of Persia tricks (Large Topic)

Discuss PoP1 for DOS here.
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NITM-T
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by NITM-T »

Cool! You're welcome, guys!
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by eien86 »

This is a new (I believe) glitch, by which screen transitions can affect the operation of door close/open tiles.



It's related to a similar phenomenon suggested to me by GMP:



So I shall, if I may, baptize it: "the GMP glitch"
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by David »

The glitch in the second video might be the same as this: https://github.com/NagyD/SDLPoP/issues/229

The second-from-last value of the bogus[] array is 0xF4, or -12.
If you count 12 tiles from the left edge of the guard's room, you get to the button next to the exit door.

Similarly, in the first video, if you count 12 tiles from the left edge of the room from which you back off, you find the raise button two rooms away.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by eien86 »

David wrote: May 23rd, 2021, 12:37 pm The glitch in the second video might be the same as this: https://github.com/NagyD/SDLPoP/issues/229

The second-from-last value of the bogus[] array is 0xF4, or -12.
If you count 12 tiles from the left edge of the guard's room, you get to the button next to the exit door.

Similarly, in the first video, if you count 12 tiles from the left edge of the room from which you back off, you find the raise button two rooms away.
This is extremely interesting. So we could systematically explore all the side effects of (left+right) bogus memory for all rooms in the game? With this, we would be immediately able to see potential weird new clips otherwise unknown. For example, if some of these room/bogus combinations could activate the big potion room doors in level 5, we could finally drink that potion.

Let me know if this is a possible direction.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by VelCheran »

So, eien86 (through the bot crem and he developed) discovered a new way to trigger the integer overflow glitch, this time on the right side of the screen. It requires to be in fight mode on the left of a screen, fall down to the left and grab the ledge at the same time.

It can be seen there, and here's my attempt to do it consistently (without relying on the randomness of the guard). My inputs are: parry, wait, strike (this is a way to hit a guard all the time, instead of striking right after the parry), right, left, left, shift. The right input is to get one pixel to the right, to be in the correct position.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by atrueprincefanfrom18 »

Norbert, maybe this could be added to PoPOT as well, you can go through the gate without the guard hitting you, as shown here. (Did it in SDLPoP, but should be possible in DOSBox too)
Love to create new MODS :)

My complete list of mods until now!

My channel. Do consider subscribing it! :)
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by dmitry_s »

There is a bug that looks similar to what VelCheran's video show. It has to do how the "dx weight" is calculated for guards or prince. That is a function that determines where the center of gravity for each frame is. And it is not calculated correctly for some of the frames with the drawn sword.

It is difficult to reproduce while fighting since you do not typically move back and forth sporadically. But it is quite easy to do in a mod where you can draw the sword with a button.

To reproduce it you have to move right and left until you end up on the right pixel. And there should be a chasm behind the tile you are on. Once you are on that pixel, the character is going to fall down on a tile that is in front of the chasm.

Guards can also fall down the same way if they stop on the right pixel after prince is not in their view. But that happens on a different frame when they sheathe the sword.

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Re: Guide to Prince of Persia tricks (Large Topic)

Post by dmitry_s »

atrueprincefanfrom18 wrote: February 7th, 2022, 5:48 am Norbert, maybe this could be added to PoPOT as well, you can go through the gate without the guard hitting you, as shown here. (Did it in SDLPoP, but should be possible in DOSBox too)
This is another bug that is easy to reproduce in a mod where you can draw the sword out with a button. The gate bump while moving backwards is not implemented correctly so you can just walk through gates by aligning a certain way.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by Norbert »

atrueprincefanfrom18 wrote: February 7th, 2022, 5:48 am Norbert, maybe this could be added to PoPOT as well, you can go through the gate without the guard hitting you, as shown here. (Did it in SDLPoP, but should be possible in DOSBox too)
For now, I've added a comment about it under tricks 39 and 158.
I get that the prince does not get hit, so I may split it off into a separate trick later.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by VelCheran »

Norbert wrote: February 7th, 2022, 12:00 pm
atrueprincefanfrom18 wrote: February 7th, 2022, 5:48 am Norbert, maybe this could be added to PoPOT as well, you can go through the gate without the guard hitting you, as shown here. (Did it in SDLPoP, but should be possible in DOSBox too)
For now, I've added a comment about it under tricks 39 and 158.
I get that the prince does not get hit, so I may split it off into a separate trick later.
It's sometimes used in speedrunning level 9 if the kid's down to 1 HP :)
dmitry_s wrote: February 7th, 2022, 8:40 am There is a bug that looks similar to what VelCheran's video show. It has to do how the "dx weight" is calculated for guards or prince. That is a function that determines where the center of gravity for each frame is. And it is not calculated correctly for some of the frames with the drawn sword.

It is difficult to reproduce while fighting since you do not typically move back and forth sporadically. But it is quite easy to do in a mod where you can draw the sword with a button.

To reproduce it you have to move right and left until you end up on the right pixel. And there should be a chasm behind the tile you are on. Once you are on that pixel, the character is going to fall down on a tile that is in front of the chasm.

Guards can also fall down the same way if they stop on the right pixel after prince is not in their view. But that happens on a different frame when they sheathe the sword.

I don't think it's the same bug, this one looks more like this (trick 16 I think):
VelCheran wrote: October 30th, 2020, 11:34 pm Hello there!
Karlgamer (world record holder on PoP1) accidentally discovered a trick, and unintentionally reproduced it.
https://www.twitch.tv/karlgamer/clip/Sm ... EyeballWow

Is it a known trick? It seems to be a very useful one (especially on this Istaria level).
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by NITM-T »

Hey, there. Can someone to try this on DOS?:



As you can see, 1st try is default, just a running jump that leads the Prince straight to death. 2nd, do you see any difference? Well, when you hold L or R or ↓ in the air, he passes the chomper in order to crouch. I don't know how that happen, but, could be a new trick?
You can find this situation in level 8 room 1 (not that is needed), but I got that idea from there.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by Norbert »

NITM-T wrote: February 24th, 2022, 1:59 pmCan someone to try this on DOS?
Thanks. I've added it as 168:
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by NITM-T »

You're welcome!
I just noticed another one in level 18 room 21 which, if we let the guard knock us down in a specific way, the Prince'll fall till room 3 n' die. I don't know if you guys already saw that, but I made a video anyway:



For now, I just thought about using the special exit to down to beat the level. I tried to hang on something or make him to cross some wall, but didn't work. Maybe I'm not doing right. Wherever a guard knock us down or by ourselves to flee the battle, the battle song will end, but in that glitch, the song keep rolling, so I think that's the reason I couldn't do something 'cause I think the game thinks the Prince's still battling even without the sword or something. There're 2 ways alike in my Shadow's Story mod that this may happen leaving us stuck in battle, too.

You guys know lots about that game, so I think you've an answer n' if works for DOS, or course. I just made a few tests, so by changing the guard's position didn't work, so I put him like it's in the original game. You've to skip his 1st attack n' turn 'round before the 2nd hits you without the sword. You'll know that worked when you hear the Prince bump in the wall twice. One is kind, default. He'll live.
I also removed the guillotine to see if he'd keep falling, but nope. Same thing.

I'd like to take this chance to show you another trick that it was meant to be a "new" trick for a new mod, but again, I didn't move one tile:



It's an exclusive one 'cause need the log which, it help us to hang on upper tiles since we can't do that by just jumping. I posted it in my channel some time ago hoping that someone'd use it. Didn't show before like others I've since is a rare thing to see a new SNES mod :P Yet, I thought this one is cool. Could be used for shortcuts, too.
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by Norbert »

NITM-T wrote: February 28th, 2022, 8:35 amI'd like to take this chance to show you another trick [...]. Yet, I thought this one is cool.
Nice find. :)
Added as 169:
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Re: Guide to Prince of Persia tricks (Large Topic)

Post by Norbert »

VelCheran wrote: February 7th, 2022, 6:11 pm[...]
VelCheran, I was looking at your Micro Palace playthrough (fun to watch), and you sure could've used knowing/remembering trick 13:
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