Hello I've recently been looking into hacking Sonic 1 for the SMS, in that time I have noticed that there seems to be a lack of information regarding the solidity data such as "how slopes work", "foreground and background layers" and so forth. Kroc Kamen managed to locate the data and the pointers and I've managed to delve a bit deeper into this. Within the hacking guide on Sonic Retro, it says that the level headers have something called the Solidity Pointer or SP. The SP value is an index which determines whic solidity pointer to use, these are located from addresses $03A65 - $03A74 I have listed these as follows: Code (Text): SP Index Address Description ---------------------------------------------------------- 0 $3A75 - $3B2C Green Hill / End Sequence 1 $3B2D - $3BBC Bridge 2 $3BBD - $3C5C Jungle 3 $3C5D - $3D0C Labyrinth 4 $3D0D - $3DC7 Scrap Brain 5 $3DC8 - $3EA7 Sky Base Exterior 6 $3EA8 - $3F27 Special Stage 7 $3F28 - $3F8F Sky Base Interior A few things I noticed were... The pointers suggest that there should only be 187 blocks opposed to 192, seeing as the data for the other blocks would cross over into the Sky Base Exterior tileset. Sky Base Exterior seems to extend to 224 blocks even though there are only 216. So with the pointer data, we can see that in most cases (except for SBZ and Sky Base Exterior), there is a byte for each block that determines what solidity to use. I have therfore listed all of the types that are used in the game, note that there are many unused byte values, which are actually different solidity types that were unsued. Code (Text): ID Description ---------------------------------------------------------- 00 None 01 Slope Steep Bottom Down 02 Slope Steep Top Down 03 Slope Steep Top Up 04 Slope Steep Bottom Up 05 Slope Shallow Top Down 06 Slope Shallow Middle Down 07 Slope Shallow Bottom Down 08 Slope Shallow Bottom Up 09 Slope Shallow Middle Up 0A Slope Shallow Top Up 0B Floor Divot Bottom 0C Slope Smooth Bottom Down 0D Slope Smooth Bottom Up 0E Slope Smooth Top Down 0F Slope Smooth Top Up 10 Floor Pass Through 11 Ski Jump To Right 12 Floor To Shallow Slope Down 13 Shallow Slope Up To Floor 14 Shallow Slope Down To Floor 15 Floor To Shallow Slope Up 16 Solid 17 Floor Divot Top 18 Shallow Slope Up To Ceiling 19 Ceiling To Shallow Slope Down 1A Ceiling Slope Steep Top Up 1B Ceiling Slope Steep Bottom Up 1C Ceiling Slope Steep Bottom Down 1D Ceiling Slope Steep Top Down 1E Ceiling 1F Ceiling Slope Shallow Top Down 20 Ceiling Slope Shallow Middle Down 21 Ceiling Slope Shallow Bottom Down 22 Ceiling Slope Shallow Bottom Up 23 Ceiling Slope Shallow Middle Up 24 Ceiling Slope Shallow Top Up 25 Shallow Slope Down To Ceiling 26 Ceiling To Shallow Slope Up 27 Floor Solid 28-7F **Undocumented** 80 Area Behind Background 81-8F **Undocumented** 90 Floor Behind Background 91-95 **Undocumented** 96 Solid Foreground 97-9D **Undocumented** 9E Ceiling With Semi Transparent Layer 9F-A6 **Undocumented** A7 Floor With Semi Transparent Layer A8 Raised Floor Platform A9-FF **Undocumented** Apologies for the naming convention for some of these, it can get a bit difficult to name each one individually seeing as they are very similar. I have provided an illustration of Green Hill where you can see the values matching the actual blocks. From this you can see that the solidity data determines the type of ground to stand on or behind. But it doesn't determine which tiles have spikes, water slides, springs, bumpers etc. This is still a mystery and I'm unsure where it could be. Anyhow I'm not sure if anyone will appreciate this seeing as there aren't many people hacking Sonic 1 SMS.
I'm interested with Sonic 1 SMS hacking and I love info you've put here! 8-bit Sonic games needs more love. Maybe there's chances for S1 SMS Level/Object Editor in future? (I'm not sure it already exist or not)
The aforementioned Kroc has been working on one, but it's been a while since he last talked about it, he only briefly mentioned it once (plus a second time a couple of weeks later in a certain private subforum), but that was 4 years ago, so I don't know about its current status. Perhaps you guys could help revive the project.
I couldn't get his editor to work on my computer. :\ Also his wife had a child a few years back, and he's working on his own forum software so he doesn't have too much time to work on his Sonic 1 SMS projects it seems. Anyways great work as always chacanger!
Well, I've hit a brick wall , I've been searching for ages trying to find the indexes for special blocks (which are blocks that are used for springs, spikes and conveyor belts). The floor layouts and slope solidity where really easy to find. One thing I tried was to find the code that causes Sonic to interact with these special blocks. There is a section documented in Krocs disassembly which refers to these 29 addresses within the ROM, after doing some further research they seem to refer to the special blocks code, or how Sonic interacts with them. Code (Text): .dw _54bc, _54c6, _54ce, _550f, _552d, _5556, _5578, _5590 .dw _55a8, _55b6, _55e2, _55eb, _565c, _567c, _56a6, _56b6 .dw _56c6, _56d6, _5761, _5771, _5781, _5791, _57cd, _57f6 .dw _5808, _584b, _5883, _58d0 I've managed to figure out what some of these refer to and listed them below, ones with "?" are ones I'm not 100% sure of. Code (Text): Address Type -------------------------------------------------------- 54BC ? 54C6 ?Ring? 54CE Ski Jump Right 550F Left Spring 552D Upwards Spring (Right Hand Side) 5556 Right Spring 5578 ? 5590 ? 55A8 Water / Also applies to water line object. 55B6 Upwards Spring (Centre) 5500 Falling Through Part 55EB Teleporter 565C ?Water? 567C ? Includes 568F - ? 56A6 ? 56B6 ? 56C6 ? 56D6 Round Bumper 5761 Weak Special Upwards Spring 5771 Medium Special Upwards Spring 5781 Strong Special Upwards Spring 5791 Tall Bumper 57CD ? 57F6 ? 5808 ? 584B ? 5883 ? 5893 ?Collapsing Bridge? 58D0 ? I thought, maybe I could figure out if these 29 were the indexes and that I could some how match them with the solidity or block data to determine which blocks were set to springs, spikes etc., unfortunately I couldn't find anything. If I knew how this worked I'd probably submit my hack to the SHC2018, but at the moment it''s looking doubtful.
