Futhark

A high-performance text rendering library for Odin. Parses TrueType (.ttf), OpenType/CFF (.otf), and variable fonts with bitmap rasterization, SDF, MSDF, GSUB shaping, and text layout — all in pure Odin with zero dependencies.

Feature Comparison

Feature	Futhark	stb_truetype	fontdue	msdfgen	FreeType
TrueType outlines	✓	✓	✓	—	✓
CFF/OTF outlines	✓	✓	✓	—	✓
Bitmap rasterization	✓	✓	✓	—	✓
SDF generation	✓	✓	—	✓	—
MSDF generation	✓	—	—	✓	—
MTSDF generation	✓	—	—	✓	—
GSUB substitution	✓	—	—	—	—
GPOS kerning	✓	partial	✓	—	✓
Text layout	✓	—	✓	—	—
Variable fonts	✓	—	—	—	✓
COLR/CPAL color	✓	—	—	—	✓
Autohinting	✓	—	—	—	✓
Font atlas packing	✓	✓	—	✓	—
OS/2 metadata	✓	—	—	—	✓
Glyph names	✓	—	—	—	✓
TrueType hinting VM	—	—	—	—	✓
Zero dependencies	✓	✓	✓	—	—

Quick Start

import tt "futhark"

// Load a font
font: tt.Font_Info
tt.init_font(&font, raw_data(font_data), 0)
scale := tt.scale_for_pixel_height(&font, 24.0)

// Render a glyph to bitmap
w, h, xoff, yoff: i32
bitmap := tt.get_codepoint_bitmap(&font, scale, scale, 'A', &w, &h, &xoff, &yoff)
defer tt.free_bitmap(bitmap)

// Lay out a string (with kerning + GSUB)
result := tt.layout_text(&font, "Hello!", {
    scale = scale, max_width = 400, wrap = .Word, apply_gsub = true,
})
defer delete(result.glyphs)

// Generate MSDF for GPU text
msdf := tt.get_codepoint_msdf(&font, scale, 'A', 4, 128, 32.0, &w, &h, &xoff, &yoff)
defer tt.free_msdf(msdf)

// Variable font at weight=700
coords: tt.Var_Coords
tags := [?]string{"wght"}
vals := [?]f32{700}
tt.set_variation(&font, &coords, tags[:], vals[:])
bitmap_bold := tt.get_glyph_bitmap_var(&font, scale, scale, glyph, &coords, &w, &h, &xoff, &yoff)

API Overview

Core — Font Loading

Procedure	Purpose
init_font(info, data, offset)	Initialize a font from raw bytes
scale_for_pixel_height(info, px)	Get scale factor for a target pixel height
find_glyph_index(info, codepoint)	Map Unicode codepoint → glyph index

Rendering — Bitmaps

Procedure	Purpose
get_codepoint_bitmap(info, sx, sy, cp, ...)	Render a glyph to a new grayscale bitmap
make_codepoint_bitmap(info, buf, w, h, stride, sx, sy, cp)	Render into an existing buffer
get_glyph_bitmap_hinted(info, sx, sy, gi, mode, ...)	Render with autohinting
get_glyph_bitmap_var(info, sx, sy, gi, coords, ...)	Render at specific variation coordinates
free_bitmap(bmp)	Free a rendered bitmap

Rendering — Distance Fields

Procedure	Purpose
get_codepoint_sdf(info, scale, cp, pad, ...)	Single-channel signed distance field
get_codepoint_msdf(info, scale, cp, pad, ...)	Multi-channel SDF (3 channels, sharp corners)
get_codepoint_mtsdf(info, scale, cp, pad, ...)	Multi-channel + true distance (4 channels)

Text — Layout & Shaping

Procedure	Purpose
layout_text(info, text, settings)	Position glyphs with wrapping, alignment, kerning
apply_gsub_default(info, glyphs)	Apply default GSUB substitutions
apply_gsub_feature(info, tag, glyphs)	Apply a specific feature (e.g. "liga")
get_codepoint_kern_advance(info, cp1, cp2)	Get kerning between two codepoints

Metrics

Procedure	Purpose
get_font_vmetrics(info, &asc, &desc, &gap)	Ascent, descent, line gap
get_codepoint_hmetrics(info, cp, &adv, &lsb)	Advance width, left side bearing
get_codepoint_box(info, cp, &x0, &y0, &x1, &y1)	Glyph bounding box
get_os2_metrics(info, &os2)	Weight, width, x-height, cap-height
get_glyph_name(info, gi)	PostScript glyph name

Variable Fonts

Procedure	Purpose
is_variable_font(info)	Check if font has variation axes
get_variation_axes(info, axes)	Enumerate axes (weight, width, etc.)
set_variation(info, coords, tags, values)	Set axis values with avar remapping
get_glyph_hmetrics_var(info, gi, coords, &adv, &lsb)	Metrics at specific axes

Atlas Packing

Procedure	Purpose
pack_begin(ctx, pixels, w, h, stride, pad)	Start packing glyphs into atlas
pack_font_ranges(ctx, data, index, ranges, n)	Pack character ranges
pack_end(ctx)	Finish packing
get_packed_quad(chardata, w, h, idx, &x, &y, &q, align)	Get UV coords for rendering

Performance

Benchmarked against stb_truetype (C), fontdue (Rust), and msdfgen (C++) on AdwaitaSans-Regular.ttf:

Operation	stb (C)	Futhark	fontdue (Rust)	msdfgen (C++)
init	46 ns	48 ns	11M ns	—
cmap lookup	10.8 ns	5.5 ns	2.2 ns	—
glyph shape	59 ns	6 ns	—	1,074 ns
bitmap	1,146 ns	2,669 ns	941 ns	—
SDF	76,862 ns	67,684 ns	—	106,242 ns
MSDF	—	242,689 ns	—	803,245 ns
kerning	64 ns	19 ns	4.2 ns	—
var bitmap	—	2,867 ns	—	—

Testing

Tests and benchmarks are on the testing branch:

git checkout testing
./tests/run_tests.sh                    # Oracle comparison vs stb_truetype
./tests/bench/run_bench.sh              # Four-way performance benchmark
./tests/correctness/run_correctness.sh  # Pixel-level comparison vs FreeType

License

Sharkk Minimal License — see license.md