Donkey Kong Forum

General Donkey Kong Discussion => General Donkey Kong Discussion => Topic started by: naujoks on February 10, 2021, 07:24:43 am

Title: Rare DK glitch
Post by: naujoks on February 10, 2021, 07:24:43 am
Here's a rare and funny DK glitch in the Pie Factory.
Does anyone how to reproduce this? :)

Title: Re: Rare DK glitch
Post by: QAOP Spaceman on February 10, 2021, 11:31:26 am

Haha yeah I saw Serphy do this a couple of weeks ago.

In thousands (probably) of hours watching folk play DK I'd never seen it before.

I thought I was possibly having a stroke
Title: Re: Rare DK glitch
Post by: rayfinkel on February 10, 2021, 11:33:49 am
you're basically just shifting up and down really quickly. in my experience, it's not terribly difficult to do it on MAME (just go crazy with up/down hitting up just slightly faster than down). i've pulled it off maybe 30-40 times on keyboard but it seems like it would be a lot more difficult on stick. not sure.
Title: Re: Rare DK glitch
Post by: Sock Master on February 10, 2021, 03:06:41 pm
I haven't looked into it in detail but here's some fact and some conjecture:

When Jumpman climbs ladders, he moves in 2 pixel jumps when he goes up or down.
To dismount a ladder, Jumpman has to be at the exact height of either of it's ends.
Ladders are always a length of an even number of pixels so this works out normally.

The retractable ladder on the Pies stage is able to pull Jumpman down 1 pixel at a time.
But the code stops pulling him down past a certain Y coordinate so this also still works out normally.

But there is some glitch when you rapidly switch between pushing up and down while climbing a ladder...
...Or perhaps simply pushing up, or maybe down, at a specific time, such that...
...the retractable ladder pulls Jumpman to an odd Y coordinate, but a joystick input also moves Jumpman so that he exits from the retracting ladder while still at an odd Y coordinate (which would normally pull him down one additional pixel).

Once Jumpman is climbing a ladder at some odd pixel step, he will no longer be able to dismount the ladder because his coordinate will not line up with the 'dismount' coordinates (since he climbs in 2 pixel steps).
So now he can climb out of range above or below the actual ladder.
Title: Re: Rare DK glitch
Post by: GILLYKONG on February 10, 2021, 08:32:52 pm
I've done this on remix a couple of times. Only once on dk
Title: Re: Rare DK glitch
Post by: Vern on March 01, 2021, 02:09:25 pm
Rayfinkle showed me this the other day. I think I had seen it before, this time I kinda get the idea of how to make it happen.