ZMJJKK123-hub Custom Font
Fonts render game text. Java Edition only.
Font Rendering
Two storage kinds:
- Bitmap fonts — glyphs in bitmaps laid out on a grid; the bitmap must have a grayscale or alpha channel (pure RGB fails to load).
- Vector fonts — glyphs as mathematical outlines (TrueType); baked to bitmaps with FreeType.
Both are rasterized into a 256×256 font texture atlas — glyphs must never exceed 256×256 px. Two render categories: grayscale (single-channel bitmaps + vector fonts; rendertype_text* shaders) and color (multi-channel bitmaps; rendertype_text_intensity* shaders).
Fragment handling: alpha (grayscale value for grayscale fonts) < 0.1 is discarded; < 1/255 renders fully opaque; semi-transparent fragments blend. Visual effects: bold = each glyph rendered twice (1 or 0.5 px horizontal offset); italic = top vertices skewed 25% right; underline/strikethrough = a line rendered above the text; shadow = the whole text rendered twice (offset down-right 1/0.5 px, 25% brightness, same alpha); glow = 9 renders (8 offsets forming a border + the normal text).
Custom Fonts
Font description files: assets/<namespace>/font/*.json:
{ "providers": [ ... ] }
Glyph Providers
Common: filter — enable/disable by options: jp (matches the "Japanese glyph variants" font option) and uniform (matches "Force Unicode Font"); both optional, absent = always enabled.
Codepoint Strings
- BMP codepoints: the literal character or
\uXXXX(4 hex digits). - Supplementary-plane codepoints: the literal string or a surrogate pair
\uXXXX\uYYYY(high = ⌊c/1024⌋+55232, low = c mod 1024 + 56320).
bitmap
file (required; → assets/<ns>/textures/<path>.png), chars (required — grid rows; every row must have the same codepoint count x; a w×h bitmap becomes an x×y grid of ⌊w/x⌋×⌊h/y⌋ cells, top-left aligned), height (default 8 — rendered glyph height; scales the source), ascent (required, ≤ height — baseline to glyph top; vertical offset).
Glyph edges: the right edge is found by scanning from the cell's right to left for the first non-zero grayscale/alpha pixel; the left edge is the cell edge. Rendering size = height/h0 scale; both dimensions must stay ≤256.
reference
id (required; → assets/<ns>/font/<id>.json): includes another font's providers (loaded once regardless of inclusion count).
space
advances (required): codepoint string → advance width in pixels (positive moves the render origin right, negative left).
ttf
file (required; → assets/<ns>/font/<path>), oversample (default 1 — resolution), size (default 11 — bake size; baked w/h = ⌊size×oversample⌋), shift (two floats −512..512: left/below offsets relative to size), skip (codepoint string or array — codepoints not provided by this provider).
unihex
hex_file (required — a zip containing .hex files), size_overrides (list of {from, to, left, right} — override glyph widths). Each .hex line: <hex codepoint (4–6 digits)>:<hex glyph data (32/64/96/128 chars)>; glyph pixel height is always 16, width = length/4; each hex digit pair = 8 pixels, 1 = opaque, 0 = transparent, row-major. Example: 0041:0000000018242442427E424242420000 (letter A, 8 px wide). The baseline sits between the second- and third-last rows; rendered glyphs are scaled down 50%.
Built-in Glyphs
Every font has two un-replaceable built-in glyphs, always first (atlas top-left): the missing glyph (hollow outline, 8×5 px; used for unknown codepoints) and the white glyph (solid white 8×5; used for underline/strikethrough).