Decomp modding basics

The development loop is as follows:

1. ./configure if you added or removed files
2. ninja to compile
3. ./run to run (will automatically run ninja if required)

splat.yaml

An important part of decomp modding is specifying where files should be linked. For our purposes, this means describing where in ROM/RAM source code and assets should go.

The file that does this is called ver/us/splat.yaml. This is a YAML file.

The segments list describes all the segments in the ROM. When adding a new file to be added to the ROM, you must add it as a segment or subsegment.

For example, to add a new map called tst_14, append this segment:

segments:
  # ...
  - name: tst_14
    dir: world/area_tst/tst_14
    type: code
    start: auto
    vram_class: map
    subsegments:
    - [auto, c, tst_14]
    - [auto]

Assets

splat.yaml has a list called asset_stack which looks like this:

asset_stack:
  - star_rod_build
  - dx
  - us

These form what we call the "asset stack". When an asset needs to be built, configure will first look for it in assets/star_rod_build, then assets/dx, then assets/us.

For example, INCLUDE_IMG("ui/input/analog_stick_left.png", ui_input_analog_stick_left_png will look in each of these directories in turn until it finds ui/input/analog_stick_left.png. This allows you to override vanilla (us) assets easily.

You should prepend a directory for your mod onto the asset stack, for example:

asset_stack:
  - my_mod
  - star_rod_build
  - dx
  - us

Then place assets for your mod in a new directory assets/my_mod.

MapFS

Map backgrounds, texture archives, geometry, and collision files live in an asset folder called mapfs. These are combined into an archive at build time.

When adding a new MapFS asset, also add it to the list in tools/splat_ext/map_data.yaml.