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2019-10-16 14:13 dustin  
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would be interesting to read who already knew this trick- i wasn't before the idea came to me a few days ago! ;d

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2019-10-16 15:55 Arno  
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i knew it already. the same amoeba-trick is applied (with other items than rockford) in existing caves, for example:  
- my cave 'testing 123456 no shortcut'  
-  trischi83 's cave 'super amoeba'  
  
also, my cave 'amoeba special' uses a slightly different trick... :-)

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2019-10-16 21:06 krissz  
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I knew this trick too. If you like these scanning tricks try to solve this cave without watching the demos:  
  
<a href="http://boulderdash.krissz.hu/cave/XEdaC5Cq1dqm/not-tested-2/" target="external">http://boulderdash.krissz.hu/cave/XEdaC5Cq1dqm/not-tested-2/</a>

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2019-10-16 22:16 shredder  
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i knew it too, from older caves :)

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2019-10-16 23:45 dustin  
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thx for feedback and caves! funny cave  krissz , this seems to work only with an amoeba! ;d

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2019-10-16 23:49 dustin  
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 Arno , i remember your testing 123456 cave from a quiz thread on the homepage! ;d the amoeba is scanned before the firefly, so the amoeba converts before the fly can explode ;d

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2019-10-17 00:05 dustin  
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thinking about this in detail, this explanation seems too simple. i experimented with slow framerate and came to the conclusion that if the amoeba is trapped, it stays an amoeba for one more frame and only then converts into diamonds! so  Arno 's 123456 cave works only because when the fly touches the amoeba, the latter is scanned twice in a row before the firefly is scanned again. am i right?

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2019-10-18 22:19 nesdori  
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almost correct. amoeba conversion to boulders or diamonds is not a separate task which is done between frames but the conversion is done in the next scan. if it's found in previous scan that all amoeba is enclosed, the amoeba is converted to diamonds piece by piece when the amoeba pieces are scanned next time. So the trick indeed only works then the amoeba piece is scanned twice before fly has a chance to do explosion check. and this is why the trick only works then the fly moves down on right side of amoeba, if it moves down on left side, the amoeba yet again determines that it's enclosed but in the next scan, a fly is scanned first and explodes although amoeba piece next to it is yelling "don't explode! i'm going to convert into a diamond right after you are scanned!" :)

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2019-10-18 22:40 shredder  
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thanks for explaining  nesdori . so thats why in cso 11 cave, amoeba converts like this:  
<a href="https://ifotos.pl/z/qsqannh" target="external">https://ifotos.pl/z/qsqannh</a>

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2019-10-18 22:54 nesdori  
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hmm.. that looks like a bug in  krissz 's engine. it seems that when conversion is activated via magic wall it does conversion immediately within the same frame although it should just set "amoeba enclosed" flag like during normal enclosure. that's how the bug works in bd1. so.. this is kinda of buggy implementation of a bug :)

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2019-10-18 23:13 shredder  
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i don't know if i understand correct the case of cso 11:  
  
when magic wall is activated, we can see the scan line? all amoeba pieces from the magic wall level to down was converted immediately, rest of amoeba in the next scan?

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2019-10-18 23:15 shredder  
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btw. i'm curious of your solution of my 060 cave :) please, show me your demo :)

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2019-10-18 23:38 nesdori  
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my demo open. yes, that's exactly what happens here; conversion is done right after magic wall drop within the same frame although is should just scan normally to the end of frame and then set "amoeba enclosed" regardless of whether amoeba is really enclosed or not and then the conversion will fully occur during the next frame. in bd1, when this bug occurs, the scan is restarted so there isn't even chance to convert right away during the same frame.

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2019-10-18 23:43 shredder  
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i like such a curiosities of bd engine :) thanks!

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2019-10-23 16:38 dustin  
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i almost forgot about this discussion, but now i read everything - thy 4 the explanation  nesdori !  shredder  - one correction. in your picture, not only the amoeba pieces behind the magic wall have converted - this would be only the lower three diamonds - but all the pieces behind the boulder have converted. this is because the magic wall gets activated when the boulder is scanned and the engine notes that it should activate the magic wall.  
 nesdori  - it is not really a bug in  krissz 's engine imo. with the bd1 engine, the amoeba would not have converted at all in  shredder 's picture because of the one piece of amoeba that was scanned before the conversion - this piece of amoeba would not count as enclosed. all modern engines that simulate this bd1-bug have simplified it this way. probably this is to make it easier for players/designers to understand the behaviour. the rule "as soon as the magic wall activates, the amoeba stops" is far easier to understand than "whenever a boulder drops through the mw, every piece of amoeba that is behind the boulder due to cavescanning order is set as enclosed for this frame" ;d  I think the way modern engines do it is a very good compromise between emulation and simplicity!