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Cave scanning order effects or "Safely touch fireflies!
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Dustin
Member


Joined: 23 Sep 2007
Posts: 446
Location: Erlangen, Germany

PostPosted: Fri Jul 31, 2020 6:18 pm    Post subject: Reply with quote

EDIT: Here's another little exercise for you: As stated above, the solution of cave 13 you see in the video was not my intended one. So can you figure out a completely different way to solve the cave?

Hint: in the intended solution, the butterfly will actually come out first!
Solution in one of the next few episodes! Idea
_________________
Boulder Dash X Rock, Paper, Scissors:
ROCKFORD collects DIAMOND, digs DIRT
DIAMOND outvalues DIRT & BOULDER
DIRT carries BOULDER, blocks FIREFLY
BOULDER kills FIREFLY & ROCKFORD
FIREFLY kills ROCKFORD, guards DIAMOND
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Dustin
Member


Joined: 23 Sep 2007
Posts: 446
Location: Erlangen, Germany

PostPosted: Wed Aug 05, 2020 8:26 pm    Post subject: Reply with quote

Episode 19 - cave 14 analysis
https://www.youtube.com/watch?v=7-3oOxrxLD8
Cave 14 ("Too Hard For Dustin's BD") starts at 0:50.
I actually had designed this puzzle cave years ago, with the intention to make
an intermission for the Dustin's BD series out of it, but I thought it's just
insane to demand from the player to first-try this... so it ended up being part
of the "CSO" series instead Laughing


What do we see?
Well, as this cave wasn't originally meant to show cavescanning order tricks in
the first place, let's try to solve the puzzle aspect of it as well.
Rockford needs 10 diamonds, which must seemingly come from the butterfly
and the free diamond. But then, there's the first problem - how to crush the
butterfly with one of the two boulders? Also, the exit is blocked off... Sad
As the video shows, there turns out to be a hidden magic wall, which allows
Rockford to crush the butterfly with the diamond and get the 10th diamond
from a boulder conversion!
Alright, but there's still another big problem - how to free the exit? It must
obviously be done with a boulder crushing the firefly, but getting one of the
boulders into the lower half seems impossible. However, the video shows how
it's done: the growing wall somehow helps to "push" the top boulder one
step to the right!
Shocked This way, the boulder gets away from the cave
border so that Rockford can now push it into the lower half without any more
problems.
(Note that it's actually a light boulder, meaning it can be pushed without
delay, but apart from that, it just behaves like a normal boulder!)

How does it work?
The bold part above is actually the real cavescan-order-trick. Let's see how it
works in detail. We start a few frames before the boulder is "magically"
moving right:
Frame 0

The firefly is an indispensible part of the action, as it's needed to stop the top
boulder from falling sideways for long enough.
Cavescanning order of the relevant elements:
1. The top boulder is blocked by the firefly.
2. The firefly is next. It notes that it can neither make a left turn nor move
straight, so it makes a right turn without moving.
3. Rockford's turn. He must snap down to free the growing wall.
4. The growing wall grows left, where Rockford has just cleared the way.


Frame 1

1. The top boulder is still blocked.
2. The firefly now moves right
3. Rockford is now threatened by the fly and must move away immediately!
4. The growing wall grows on.

Frame 2

Now comes the decisive moment! Attention, please! Very Happy
1. The top boulder is now free! So it starts to fall sideways from the
bottom boulder! That means it moves one step right and thereby becomes a
"falling boulder" because it thinks it can fall down into the empty space in the
next frame!

2./3. The firefly and Rockford are no longer part of the action.
4. Now the growing wall grows on and blocks the empty space where the
boulder intended to fall!


Frame 3

The top boulder is scanned. It's furious - why can't it fall down when there
has been empty space just one frame before?! The growing wall makes an
innocent "it wasn't me!" face, but we know the truth... Very Happy
So that's how the magic works! The boulder started to fall sideways in
frame 2 because it "saw" empty space to its right AND to its bottom-right. So
it moved right, intending to fall down next frame. But in the same frame, the
growing wall "trolled" the boulder by blocking the way!


Actually, the same trick can be done at the right border and it's even a lot
simpler then. I haven't prepared an image to illustrate this, so let me do some
"good old ASCII art" again ;D
DDDDT
DDDBT
DGRBT
DDDDT
D=Dirt, B=Boulder, R=Rockford, G=Growing wall, T=Titanium wall
If Rockford moves up by two steps in this scenario, the top boulder will move
one step left!
I'll leave it as an exercise to you if you want to make a frame-by-frame
analysis here. Also, you might want to find out why this works without a
firefly, while the firefly was strictly necessary in the above cave!
The solution to this exercise and the one from episode 18 will come in the
next episode! See you there! Bye

EDIT: Actually the trick analyzed in this episode has been seen many times
before (the same goes for many other cavescan order tricks as well), but I
don't have any concrete videos at hand. Arno (or someone elase), if you have
a nice video in mind that fits into this episode, it'd be cool to have the link
here! Very Happy
_________________
Boulder Dash X Rock, Paper, Scissors:
ROCKFORD collects DIAMOND, digs DIRT
DIAMOND outvalues DIRT & BOULDER
DIRT carries BOULDER, blocks FIREFLY
BOULDER kills FIREFLY & ROCKFORD
FIREFLY kills ROCKFORD, guards DIAMOND
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Dustin
Member


Joined: 23 Sep 2007
Posts: 446
Location: Erlangen, Germany

PostPosted: Fri Aug 07, 2020 9:26 pm    Post subject: Reply with quote

Episode 20 - Solutions and cave 15 analysis

I Solution to the exercise of episode 18
Here's the intended solution of cave 13:

Instead of the solution you see in the video and which I explained in episode
18, my intended way to solve the cave was the following:

The trick is to manoever a boulder between the fire- and the butterfly, so that
it blocks off the firefly but not the butterfly. More precisely, the cavescanning
order now works as follows:
1. The firefly is scanned first and, as the boulder blocks its way, it turns right
without moving.
2. The boulder itself is next and falls down.
3. The butterfly can come out now, because the boulder has just moved out of
the way.
4. Rockford moves down to escape the boulder.
So the next frame, we have the following picture:

1. The firefly is first again. It still tries to come out, but now the butterfly is in
the way! So the firefly was blocked off two frames in a row, which
means it turns right again and now faces left, ready to move into its cage
again!
2. The butterfly turns right and thereby moves up from our point of view.
3./4. The boulder falls again and Rockford moves out of its way.

The "cavescan order action" is over - the firefly will now need many seconds
to come out of the cage, so there's enough time to crush the butterfly and exit
before the firefly runs into the (upper) voodoo.
But wait! Won't the butterfly kill the voodoo now? Um... I actually forgot to
clear some dirt in the images... before manoevering the boulder between the
flies, Rockford should have cleared a path for the butterfly in a way that the
bfly will move around the right cage and thereby avoid the voodoo! Then
Rockford has enough time to crush the butterfly, collect the diamonds and exit
before the firefly will touch the upper voodoo.

II Solution to the exercise of episode 19
That was just two days ago, so don't read on if you still want to do it for
yourself ;D
Frame 0
DDDDT
DDDBT
DGRBT
DDDDT
D=Dirt, R=Rockford, B=Boulder, T=Titanium wall, G=Growing wall
Let's see what happens if Rockford moves up two steps:
Frame 1
DDDDT
DDRBT
DGSBT
DDDDT
S=Space
We see again that a growing wall which touched Rockford from left does not
immediately fill the gap that Rockford left behind. Now in the next frame, a lot
will be going on, so let's check the cavescanning order:
1. Rockford moves up.
2. The top boulder sees enough empty space to its left to start falling
sideways from the bottom boulder.
3. The growing wall grows right.
Frame 2
DDRDT
DDBST
DGGBT
DDDDT
So here we see the same thing as discussed in episode 19 - the top boulder
"thought" it could fall sideways, but in the same frame it was blocked by the
growing wall, so it just "magically" moved one step left!
And why doesn't it work the same way if everything is mirrored?
TDDDD
TBDDD
TBRGD
TDDDD
The experienced reader of this thread will know the answer immediately: If
Rockford moves up here, the growing wall (now toucvhing Rockford from
right) will immediatelyfill the gap, so that the next picture looks as
follows:
TDDDD
TBRDD
TBGGD
TDDDD
Now it's clear that the boulder will never start falling sideways anymore, which
means the whole trick doesn't work this time. That's why in cave 13, it was
necessary to "ask" a firefly for help!

III Cave 15 analysis
https://www.youtube.com/watch?v=7-3oOxrxLD8
Cave 15 (""Voodoo Shooting") starts at 1:31.
Actually this analysis will be relatively short, because we've seen the same
trick already in episode 18/cave 13. Here's the map:

This cave is highly inspired by an Arno Dash intermission! Very Happy

What do we see?
Rockford must somehow get past the two "voodoo walls" to reach the exit. In
the video, you see that he blasts the flies next to the voodoos and survives, as
if the voodoos were just normal brick walls!

How does it work?
The decisive moment is when a fly hits the voodoos:

The clou is that the boulder is scanned before the fly. So the boulder kills
the fly before the fly kills the voodoo!
This leads visually to the same
thing - the fly is crushed and so are three voodoos - but the strange voodoo
rules state that Rockford only explodes if a fly explodes a voodoo! Here, it was
the boulder that (indirectly) killed the voodoos, and that means that
Rockford is not harmed! Laughing

In the next episode, we'll see how it's even possible to blast through a
bidirectional growing wall using cavescanning order tricks! Don't miss that
one! Very Happy
_________________
Boulder Dash X Rock, Paper, Scissors:
ROCKFORD collects DIAMOND, digs DIRT
DIAMOND outvalues DIRT & BOULDER
DIRT carries BOULDER, blocks FIREFLY
BOULDER kills FIREFLY & ROCKFORD
FIREFLY kills ROCKFORD, guards DIAMOND
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Arno
Site Admin


Joined: 17 Mar 2007
Posts: 2386
Location: netherlands

PostPosted: Fri Aug 07, 2020 9:55 pm    Post subject: Reply with quote

Dustin wrote:
Actually the trick analyzed in this episode has been seen many times before (the same goes for many other cavescan order tricks as well), but I don't have any concrete videos at hand. Arno (or someone elase), if you have a nice video in mind that fits into this episode, it'd be cool to have the link here! Very Happy

Here are a few caves using the trick of moving a boulder/diamond by activating a g-wall: Smile
- https://www.youtube.com/watch?v=S6K0enGlbD0
- https://www.youtube.com/watch?v=eeLWCmOWCok
- https://www.youtube.com/watch?v=lU-jvFXwtbY
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