Bd1 games and custom elements

[subotai]

Morning

I'm looking for bd1 engine games with custom elements. I know that there should exist games with growing walls, slime and acid. I also know that there are some games with "non-rounded" brick walls. I can't find any game, that supports the growing wall and I can't find any that supports the slime. Maybe somebody can help me. And do you know any other custom elements or effects for bd1 games?

Thanks in advance.
subotai

[LogicDeLuxe]

I first coded the acid in Crazy Dream 3 and later moved it to other engines. Crazy Dream 3 also supports slime, growing walls and the dirt mod. There are also voodoo dolls, but they are not coded very efficiently.

For the non-rounded bricks, they are like explodible steelwall and non-eatable dirt. Those are basically exploiting the unused elements of the BD1 engine, which do nothing. The only difference is, that the author of the game adjusted the graphics pointer to their needs. No One did this occasionally. No One Boulder 31 is one of them using non-eatable dirt.

[subotai]

Thanks for your reply ! Do you know if there are any other bd1 engine games that use the growing walls? And are there different settings for the slime permeability, or can I always set it to "0"?

Please, can you explain, how acid works? I read in the gdash-thread how I can get the speed of acid and the element that is eaten. But I don't know how to use this knowledge. Seems for me that acid spreads randomly.

[LogicDeLuxe]

Thanks for your reply ! Do you know if there are any other bd1 engine games that use the growing walls?

I'm not aware of any.

And are there different settings for the slime permeability, or can I always set it to "0"?

I don't remember every detail about it. Permeability might well be fixed to 0 here.

Please, can you explain, how acid works? I read in the gdash-thread how I can get the speed of acid and the element that is eaten. But I don't know how to use this knowledge. Seems for me that acid spreads randomly.

It's really just a check against an unpredictable random number. Nothing special.

[subotai]

Ok, the spreading of acid is really simple. But I'm not sure about the acid speed. In the CrLi-Tools I found out that if the acid speed is set to "0", the acid seems not to grow at all, and if it is set to "255", it seems to grow in every scan. So I would implement it like this:

Code: Select all

IF Acid_Speed > 0 then
   BEGIN
   IF random(256-Acid_Speed)=0 then
       ACID_SPREAD;
   END;

Sorry if this is a bit off topic.

[LogicDeLuxe]

The code looks like this (from a disassembly not optimized for readability):

Code: Select all

T_2600		jsr	P_2500		; $2600 , $2500
		cmp	$03A8
		bcs	B_264E

At 2500, a random number is generated. 03a8 is the acid speed and right after the bcs is the spreading code, which ends at 264e.

So it's more like:

Code: Select all

IF random(256) - Acid_Speed < 0 then
  ACID_SPEAD;

At maximum speed, a 1 out of 256 chance remains for each acid piece not to spread.

[subotai]

Thanks a lot
You are good. I couldn't make it this far in my remake without your help. But, you know that

[subotai]

Ok, the slime permeability in CrazyDream 03 is stored at offset $16 of the cave data. It uses a predictable random number. Using the value $00 for both starting seeds instead of $1E and $00 for PLCK games seems to work approximately fine, but I'm not sure about this.

Unfortunately, I can't check the code because I have no skills in assembly

subotai

[LogicDeLuxe]

It should behave like BD2, iIrc, ie. the seed remains at whatever it is after the random placement.