Terrarum-sans-bitmap/.claude/skills/add-unicode-block/SKILL.md

name, description

name	description
add-unicode-block	Add a new Unicode script/block to the Terrarum Sans Bitmap font engine.

Add Unicode Block

Required inputs

The user must supply:

• Script name — human-readable name used in constant/function names (e.g. Ogham, LatinExtE)
• TGA filename — the sprite sheet filename without path (e.g. ogham_variable.tga)
• Unicode range — start and end codepoints inclusive (e.g. U+1680..U+169F)

If any of these are missing, ask for them before proceeding. Extra directions can be given after Unicode range.

Step 1 — Determine the next sheet index

Read the sheet index constants from both files to find the current highest index (excluding SHEET_UNKNOWN = 254):

• Kotlin: src/net/torvald/terrarumsansbitmap/gdx/TerrarumSansBitmap.kt — grep for internal const val SHEET_
• Python: OTFbuild/sheet_config.py — grep for ^SHEET_

The new index = highest existing index + 1.

Step 2 — Derive identifiers

From the script name, derive:

• Kotlin constant: SHEET_<UPPER_SNAKE>_VARW (e.g. SHEET_OGHAM_VARW)
• Kotlin indexY function: <camelCase>IndexY (e.g. oghamIndexY)
• Python constant: same as Kotlin constant
• Range start hex: the lower bound codepoint as a 0x-prefixed Kotlin/Python literal

Step 3 — Edit both files

Make all 6 edits. Read each section before editing.

Kotlin: src/net/torvald/terrarumsansbitmap/gdx/TerrarumSansBitmap.kt

a) Sheet index constant — find the block of internal const val SHEET_* constants (just before SHEET_UNKNOWN = 254) and append:

internal const val SHEET_<NAME>_VARW = <INDEX>

b) fileList entry — find internal val fileList array and append before the closing ):

"<tga_filename>",

c) codeRange entry — find internal val codeRange array and append before the closing ):

0x<START>..<0x<END>, // SHEET_<NAME>_VARW

Use + to combine non-contiguous ranges if needed.

d) getSheetwisePosition when-branch — find the when block that dispatches to indexY functions (just before else -> ch / 16) and append:

SHEET_<NAME>_VARW -> <camelCase>IndexY(ch)

e) indexY function — find the block of private *IndexY functions near the bottom of the companion object and append:

private fun <camelCase>IndexY(c: CodePoint) = (c - 0x<START>) / 16

Python: OTFbuild/sheet_config.py

f) Sheet index constant — find the block of SHEET_* = <n> constants (just before SHEET_UNKNOWN = 254) and append:

SHEET_<NAME>_VARW = <INDEX>

g) FILE_LIST entry — find FILE_LIST = [ array and append before the closing ]:

"<tga_filename>",

h) CODE_RANGE entry — find CODE_RANGE = [ array and append before the closing ]:

list(range(0x<START>, 0x<END+1>)),                                                  # <INDEX>: <ScriptName>

i) index_y lambda — find the dict in get_index_y(sheet_index, c) (just before SHEET_HANGUL: lambda: 0) and append:

SHEET_<NAME>_VARW: lambda: (c - 0x<START>) // 16,

Step 4 — Verify

After all edits, confirm:

1. The Kotlin constant, fileList, codeRange, when-branch, and indexY function are all present and consistent.
2. The Python constant, FILE_LIST, CODE_RANGE, and index_y lambda are all present and consistent.
3. The indices in both files match.
4. The range end in CODE_RANGE is end + 1 (Python range is exclusive).