EMC difference in rocks dropping on magic wall?

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filbo
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Joined: Fri Jun 20, 2014 10:06 am

EMC difference in rocks dropping on magic wall?

Post by filbo »

In The Exception Two level 64 (levels/Emerald Mine Club/emc_exception_2/64). I reach a place where I need a rock to drop through a quicksand to crack a nut. The only available rock is in a blocked quicksand above a magic wall which is already running (and infinite).
emc_exception_2-64.png
emc_exception_2-64.png (10.17 KiB) Viewed 2192 times
If this level worked on real EMC, it seems like there must have been a way to interrupt the falling of that rock; to push it aside before it fell through the magic wall.

This seems to imply a difference in how the engines handle pushing a rock which is currently falling.

A dynamite would solve the problem (blow up the magic wall); but there's only 1 in the level, I have to get past this point to collect it, and it has a definite purpose elsewhere.

Am I missing something? Testing in 4.2.0.3 (release, my build).

Partial tape up to that point attached.
emc_exception_2-64.tape
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filbo
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Re: EMC difference in rocks dropping on magic wall?

Post by filbo »

This could actually be the same problem as in viewtopic.php?f=8&t=3161, regarding The Exception Two level 35. Here I need to be able to snap-push or push a falling rock; there I need to be able to snap-collect a falling emerald.

So that seems like a stronger implication that the engine under which EMC The Exception Two was created & tested had those properties...?
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Holger
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Re: EMC difference in rocks dropping on magic wall?

Post by Holger »

This is interesting. Manipulating things that are falling down is something that is impossible in the EMC engine (while it is allowed and possible, if timing is correct, in the R'n'D engine).

But in that level part above, it really looks heavily like it is intended to push that rock at the moment it touches the magic wall, but before it vanishes into it.

However, I think the key for this part of the level is the magic wall being active forever. I have the suspicion that this is the part that differs from the original game.

The old version of the EMC engine code has the following comment in "convert.c":

Code: Select all

 * - different timing for wonderwall break some cave in exception mine 2.
So this seems to be the case here.

Have you ever tried to play that level with the original EMC disk image using an Amiga emulator like UAE? How does that wonderwall behave in the original engine?

I will also try to test this...
filbo
Posts: 647
Joined: Fri Jun 20, 2014 10:06 am

Re: EMC difference in rocks dropping on magic wall?

Post by filbo »

I've never run any original EMC anything! :)

Just now I fiddled with fs-uae a bit on my Ubuntu install, found it as baffling as last time I did, and stopped... Perhaps it would help if I had some Amiga ROMs, but I don't. The two built-in games were able to display something (one of them even displayed its menu), but not actually do anything like 'play a game'.

=====

Your hypothesis could work for this example, level 64, but I don't think it works for level 35. It could work for 35, but the timing is absurd:

The first magic wall is used (in my runthrough) at 1:19; and the last one at 2:40, at which point the first object (diamond) would have to fall through, then the magic wall timer run out before the next one (emerald) hits it; which is split-second timing 80+ seconds after magic wall was first activated. I disbelieve the level design is that specifically timing dependent!

These levels are strongly linear (you have to do almost everything in the specified order), so that 80+s split-second timing would be forced on all players -- to collect a single emerald which they wouldn't know until another 3 game-minutes later was necessary to complete the level. Most of the levels in this levelset have 2-3 spare emeralds so it's normal to have a couple of emeralds you miss.
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