Sonic the Hedgehog 2 (16-bit)/Art Editing
From Sonic Retro
| Sonic Community Hacking Guide Sonic the Hedgehog 2 (16-bit) |
|---|
| Art |
| Objects |
| Levels |
| Text |
| Music |
| RAM |
| Miscellaneous |
There are several different tools that can be used to edit art besides the hex editor. SonED is probably the best tool to use for editing level art, and can also be used on palettes. HivePal is also a great tool for editing palettes. Sonik Sprite is useful for editing uncompressed art; it gets its name from its ability to edit Sonic's sprites. LOst Library is most likely the best choice for editing compressed art in the Nemesis format.
If, however, you still want to do it yourself, your best bet is to download the Sonic 2 Split disassembly here. Decompress the archive into a new folder, and place your S2 ROM, in binary format and named "S2.bin", in that folder. Run the batch file "split.bat". This will split up all the art into its own binary files, which you can then decompress and edit. When you're done, run "combine.bat".
Uncompressed Art Locations
Most of this information was taken from Nemesis's guide. Please excuse any mistakes or misunderstandings, as that guide wasn't exactly well-written. A description is written in parentheses after the original name if I deem it necessary; if I don't know what it is, "Unknown" appears in that place. Please correct this if you know. It doesn't list the number of blocks taken up, so if you know, put it in. Otherwise, I'll find out eventually.
| Offset | Description | # of blocks |
|---|---|---|
| Zone Independent | ||
| $50000 | Sonic | ? |
| $64320 | Tails | ? |
| $71FFC | Splash | ? |
| $7287C | Spindash smoke | ? |
| $7A18A | Signpost | ? |
| $7AF80 | Drowning countdown | ? |
| $7CD30 | Option and level select menu background | ? |
| Emerald Hill Zone | ||
| $49714 | Animated flowers | ? |
| $49914 | Pulsing orb on walls | ? |
| Chemical Plant Zone | ||
| $4FAFE | Part of background | ? |
| Aquatic Ruin Zone | ||
| $4FCFE | Waterfall | ? |
| Casino Night Zone | ||
| $4D4FE | Flipping square in foreground | ? |
| $4EEFE | Slot machine pictures | ? |
| Hill Top Zone | ||
| $49714 | Animated flowers | ? |
| $4A33E | Clouds from background | ? |
| $4B73E | Lava | ? |
| Mystic Cave Zone | ||
| $894E4 | Rocks that fall from ceiling during boss fight | ? |
| Oil Ocean Zone | ||
| $49914 | Pulsing orb on walls | ? |
| $4BF7E | Pulsing ball | ? |
| $4C0FE | Square rotating around ball (Unknown) | ? |
| $4C4FE | Oil | ? |
| Metropolis Zone | ||
| $4A73E | Rotating net | ? |
| $4B73E | Lava | ? |
| $4BD3E | Parts of background | ? |
| Death Egg Zone | ||
| $4FAFE | Part of background | ? |
Compressed Art Locations - Nemesis format
See SCHG:Sonic 2/Nemesis Compressed Art.
Compressed Art Locations - Kosinski format
- $95C24 - EHZ/HTZ main level patterns
- $9DB64 - MTZ main level patterns
- $A4204 - OOZ main level patterns
- $A9D74 - MCZ main level patterns
- $B0894 - CNZ main level patterns
- $B6174 - CPZ/DEZ main level patterns
- $BCC24 - ARZ main level patterns
- $C5004 - SCZ/WFZ main level patterns
- $DCA38 - Special stage floor patterns
Palette Editing
Usually, it's not really necessary to edit a palette in hex. Palette editors give you instant feedback for each RGB value, and the palette can be easily saved as a separate binary and reimported into the ROM. However, it is sometimes desireable or necessary to do it in hex, and it can't hurt to know how it's done.
These are the ROM offsets of the palettes in Sonic 2, as listed by HivePal:
| Name | Offset |
|---|---|
| Sega Sonic | $2902 |
| Title Screen (Sonic) | $133EC |
| Title Screen (Tails) | $2942 |
| Title Screen (Main) | $1340C |
| Title Screen Water | $1E5A |
| Sonic and Tails | $29E2 |
| Sonic to Super Sonic | $2246 |
| Super Sonic | $2276 |
| Title Cards | $2A02 |
| Emerald Hill | $2A22 |
| Emerald Hill/Aquatic Ruin Rotating Water | $1E7A |
| Wood | $2A82 |
| Wood Conveyor Belts | $1F1A |
| Metropolis | $2AE2 |
| Metropolis Cycle #1 | $1F2A |
| Metropolis Cycle #2 | $1F36 |
| Metropolis Cycle #3 | $1F42 |
| Wing Fortress | $2B42 |
| Wing Fortress Fire Cycle | $20A2 |
| Hill Top | $2BA2 |
| Hill Top Lava | $1E9A |
| Hidden Palace | $2C02 |
| Hidden Palace (Sonic & Tails Under Water) | $2C62 |
| Hidden Palace Underwater Tiles Pallete | $2C82 |
| Hidden Palace Water Cycle | $1F56 |
| Hidden Palace Underwater Cycle | $1F66 |
| Oil Ocean (Do not edit or you'll get a huge mess unless you know how to fix it!) | $2CE2 |
| Oil Ocean Oil | $1F76 |
| Mystic Cave | $2D42 |
| Mystic Cave Lanterns | $1F86 |
| Casino Night | $2DA2 |
| Casino Night Cycle 1 | $1F8E |
| Casino Night Cycle 2 | $1FA0 |
| Casino Night Cycle 3 | $1FB2 |
| Casino Night Cycle 4 | $1FC4 |
| Chemical Plant | $2E02 |
| Chemical Plant Sonic & Tails Underwater | $2E62 |
| Chemical Plant Underwater | $2E82 |
| Chemical Plant Underwater Sonic to Super Sonic | $22C6 |
| Chemical Plant Underwater Super Sonic | $22F6 |
| Chemical Plant Cycle 1 | $2022 |
| Chemical Plant Cycle 2 | $2058 |
| Chemical Plant Cycle 3 | $2082 |
| Chemical Plant Cycle 4 | $20E2 |
| Death Egg | $2EE2 |
| Aquatic Ruin | $2F42 |
| Sonic & Tails Underwater (Aquatic Ruin) | $2FA2 |
| Aquatic Ruin Underwater | $2FC2 |
| Sonic to Super Sonic Underwater (Aquatic Ruin) | $2346 |
| Aquatic Ruin Underwater Super Sonic | $2376 |
| Sky Chase | $3022 |
| Menus | $30E2 |
| Special Stage Main | $3162 |
| Special Stage Sonic | $3182 |
| Special Stage Tails | $31A2 |
| Special Stage 1 | $31C2 |
| Special Stage 2 | $31E2 |
| Special Stage 3 | $3202 |
| Special Stage 4 | $3222 |
| Special Stage 5 | $3242 |
| Special Stage 6 | $3262 |
| Special Stage 7 | $3282 |
| Special Stage 1 2p | $32A2 |
| Special Stage 2 2p | $32C2 |
| Special Stage 3 2p | $32E2 |
| Special Stage Chaos Emerald | $35F92 |
| Special Stage Results Screen | $3302 |
| Emerald Hill Icon | $9880 |
| Metropolis Icon | $98A0 |
| Hill Top Icon | $98C0 |
| Hidden Palace Icon | $98E0 |
| Oil Ocean Icon | $9900 |
| Mystic Cave Icon | $9920 |
| Casino Night Icon | $9940 |
| Chemical Plant Icon | $9960 |
| Aquatic Ruin Icon | $9980 |
| Sky Chase Icon | $99A0 |
| Wing Fortress Icon | $99C0 |
| Death Egg Icon | $99E0 |
| Special Stage Icon | $9A00 |
| X 2 Player Versus Icon | $9A20 |
| Sound Test Icon | $9A40 |
| Ending Grey Cutscenes | $AD1E |
| Ending Main | $ACBE |
| Ending Sonic | $AC7E |
| Ending Tails | $AC9E |
| Ending Super Sonic | $AD3E |
| Unknown 1 | $3082 |
| Unknown 2 | $30A2 |
| Oil Ocean Zone Boss (Pallete line 1) | $30C2 |
For details of the palette data format, see Megadrive Palettes.
Pattern Load Requests
Nemesis named this structure the "pattern load queue". However, this name tends to confuse the RAM structure (which is actually a queue) with the ROM structure (which is a set of data to be loaded into the queue).
PLRs tell the game engine where to get Nemesis-compressed art data and where to put it. The format is rather simple, and can be described with this pseudocode:
struct plr{
long *compPattern;
word vramStartLoc;
};
struct plrList03{
const word plrCount = 3;
plr plrArray[3]
} plr000;
plrCount is the length of plrArray. compPattern is a pointer to Nemesis-compressed patterns, and vramStartLoc is the VRAM address where the patterns are to be decompressed to.
The RAM queue is $60 bytes long, meaning it has space for 16 PLRs. Note that the routines that load PLRs into the queue do not do any bounds checking, and it is quite easy to create a buffer overrun condition. Further, both lists seem to be moved into the queue at the same time, so even if neither one is longer than 16 requests, they can still overrun the queue and destroy the variables that are stored just beyond it. Make sure that the primary and secondary PLR lists are no more than 16 requests long.