Sonic 2 Hacking Guide
Genecyst Savestate - Mappings
Mappings is defined as building an object from small objects. There are two types of mappings. 128x128 objects (floor design objects) are built of smaller 16x16 blocks. This is generally known simply as 128x128 mappings. 16x16 blocks are made of smaller 8x8 (sprites) blocks. This is known as 16x16 mappings. Let's start with 16x16 mappings.
Screen Mappings
01E478 - Starting address
FORMAT:
#1 #2
1 + 2 - 8x8 tile to use
Mapping the screen allows you to change what tiles are currently being displayed and where. It starts at the top-left position of the screen and it reads each pair of two bytes to deside which 8x8 tile to use. It moves to the right, and moves down after a row is finished. Each row of 8x8 tiles on the screen uses 128 bytes (making use of 64 tiles, but only showing 40 of them).
16x16 Mappings
00B478 (9000) - Starting address
FORMAT:
#1 #2
1 - Upper object value (flag)
2 - Lower object value
I could put every single 8x8 object on this page for a quick resource, but it's simply too much trouble. The 8x8 objects are listed in order in Genecyst. Just goto 'View' and then 'Patterns'.
Every 8 values on the upper object value, the object will change direction. Every 32 values on the upper object value results to a palette change.
128x128 Mappings
002478 (0000) - Starting address
FORMAT:
#1 #2
1 - Upper object value (flag)
2 - Lower object value
Every 4 values for the upper object value will allow the object to change direction. Every 16 values for the upper object value will change it's properties (wall, ceiling, floor, etc).
Now that you know the basic format for this, you are now ready to see what each tile is. Listed are all the pages with tiles I have (so far, just 1)