Checkered terrain
The checkered terrain, often used in small bonus rooms
behaves quite differently from just about any other terrain type, as the first param is "type"
| first param | bank 1, id 2e (five bytes) | bank 0, id 4f (four bytes) |
|---|---|---|
| 0 | interior pattern (see below) | lower right corner (wall-ceiling merge) |
| 1 | upper left corner (wall-ceiling) | lower left corner (right wall-merge) |
| 2 | ceiling | upper left corner (right wall-merge) |
| 3 | upper right corner (wall-ceiling) | upper right corner (floor-merge) |
| 4 | left wall | upper left corner (floor-merge) |
| 5 | right wall | lower right corner (left wall-merge) |
| 6 | lower left corner (wall-floor) | upper right corner (left wall-merge) |
| 7 | floor | one tile only |
| 8 | lower right corner (wall-floor) | left end (one-tile-tall) |
| 9 | lower right corner (wall-ceiling) | top (one-tile wide) |
| a | lower left corner (wall-ceiling) | bottom (one-tile-wide) |
| b | upper right corner (wall-floor) | N/A |
| c | upper left corner (wall-floor) | N/A |
| d | lower left corner (wall-ceiling merge) | four-way intersection |
| e | middle (one-tile-tall) | T-merge (to-floor) |
| f | right end (one-tile-tall) | T-merge (to-ceiling) |
| 10 | N/A | T-merge (right side-to-wall) |
| 11 | N/A | T-merge (left side-to-wall) |
the fifth byte is the parameter, which is usually length/width, except unlike just about every object in the game, it is not "plus one"
For corners, seems the parameter should be 1
Other objects are also used to define bonus room terrain, like bank 4(width), id 6b, which is the middle of a one-tile-wide platform.
47 5 16 2e 4 -- a checkered floor at (5,16) with length of 4
48 9 16 2e 1 -- lower right corner at (9, 16)
This is the checkered terrain with no edges, used to fill in interior areas. It is six bytes with byte 5 being width and byte 6 being height. Width is like other checkered objects in that it's the same width as its value. Height is unlike other checkered terrain in that it is "minus one", like almost all other dimensional objects in the game.
40 y x 2e 4 2 -- interior pattern that is 4 tiles wide and 3 tiles tall.
so far, most checkered terrain have a very large set of compatible object sets. But inner lower right corner (param 48) has a very small set of object sets as does outer upper right corner. I have a feeling this will play out broadly, with many having the large set quantity and many having the small set quantity.
When doing an object dump for lower right corner, it looks like an alternative checkered terrain piece is rendered in the other object sets?
