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I'm saving money to buy this (though if someone has unclaimed giftcodes and likes classic JRPG games, give me a ring, I got few unclaimed RPGs from RPG Maker bundle and I think VX Ace, games that I either don't want or already have so trade can be arranged), but I want to ask few questions before I do so (going to buy it either way, these are just some stuff I want to do in my game and want to know how):

  • How hard is to make multi-sprite character walking around? (I'm talking about 16x32 sprite because my character needs to be bit detailed)
  • How do you manage transparent sprites (so if I use, say color 5 for background, because I need some black stuff in my char for my character to not have "frame" around it when it walks, say in front of a bush)
  • Can I use demos provided as template for my game? Particularly platformer demo as game will have platformer sections)
  • How do you manage bigger games, when map is only 128x32 (+same shared with sprites)? I'm talking about more advanced platformers, such as: https://www.lexaloffle.com/bbs/?tid=2145&autoplay=1#pp
P#12887 2015-08-22 15:10 ( Edited 2015-08-26 17:37)

  • the "spr" command has optional width and height parameters, so you can draw a block of sprites with a single command.
  • the "palt" command can be used to set transparency colors. By default black is transparent, but you can change that.
  • pico-8 comes with a platformer demo called Jelpi, and you can load any cart and see its code. If your question is about licensing issues, people seem to have take Jelpi as fair game for modification.
  • zep posted a compression demo to show how to fit more data onto a cart.
P#12893 2015-08-22 15:57 ( Edited 2015-08-22 19:57)

Okay... Thank you. BTW, how do you dl carts from bbs so you can see their code in Pico? Mainly I'm talking about that compression thing, but also I want to check how collision is done by various games.

P#12896 2015-08-22 16:16 ( Edited 2015-08-22 20:16)

Click on the screenshot image to see a cart's .p8.png file. That kind of IS the cart; the stuff's all squirreled away in there. Save it to your HD in your Pico-8 carts folder, then you can load it in Pico-8.

P#12897 2015-08-22 17:14 ( Edited 2015-08-22 21:14)

Cool, thanks. Anyone knows how data is encoded into PNG? I kinda consider making for my game, Computer Virus Simulator (google it, there's thread on TigSource and you'll need to google with quotes) a similar system where whole level is encoded into a PNG which also serves for level's screenshot, but I need to know how to achieve it.

P#12899 2015-08-22 18:33 ( Edited 2015-08-22 22:33)

It's stored in the image data itself, presumably in the least significant bits.

with a bit of image tweaking you can see the data in there:

I might have a go at trying to figure out how it's layed out soon.
I suspect there's some compression on the code content.

P#12908 2015-08-22 23:40 ( Edited 2015-08-23 03:40)

Yeah, I've figured as much, but what is the algorithm?

P#13026 2015-08-23 21:53 ( Edited 2015-08-24 01:53)

Oh gosh, I had hoped it was some kind of steganographic embedding but assumed that was asking too much and that it was just hidden in some PNG metatags or something. That's fantaaaaastic.

P#13108 2015-08-24 21:17 ( Edited 2015-08-25 01:17)

Guessing from looking at the pixels,

It appears to be, from the top:

very much like the contents of a p8 file:
gfx data
gff (probably)
map
sfx (those diagonally spaced red dots mark the start/end of each sfx block, probably the speed)
music (not sure but it's probably there)
big block of noise at the bottom is the compressed code
(i suspect it uses the same compression system as the "compress" function in pico8.)

P#13110 2015-08-24 22:09 ( Edited 2015-08-25 02:09)

So I've managed to get out the spritesheet and map data, the rest should be faily trivial other than figuring out the code compression.

Data is stored in the least two significant bits of each channel so you get one byte of pico8 data per cartidge image pixel (2 bits * 4 channles = 8 bits).

Colour ordering is BGRA.

Spritesheet+shared data is first 8192 bytes.
Map is the next 4096 bytes
...

P#13145 2015-08-25 22:38 ( Edited 2015-08-26 02:38)

Oh cool. Thanks.

P#13172 2015-08-26 13:37 ( Edited 2015-08-26 17:37)

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