Spectral Terminal Emulator

A next-generation terminal emulator written in Rust, designed to be faster than Ghostty while solving its biggest user frustration: font rendering that looks too thin.

What Makes Spectral Different

1. Cross-Platform Font Thickening (Finally!)

Ghostty's #1 user complaint is that fonts look thinner than other terminals — and on Linux there's no fix. Spectral solves this with a shader-based thickening system that works identically on macOS, Linux, and Windows.

# Spectral config (works on ALL platforms)
font-thicken = true
font-thicken-strength = 0.5    # 0.0 = thin, 1.0 = bold

The MSDF (Multi-Channel Signed Distance Field) renderer allows per-pixel threshold adjustment in the GPU fragment shader. No platform-specific hacks — just one clean cross-platform solution.

2. True Cross-Platform Native GPU Backend

Platform	Graphics API	Why
macOS	Metal (via wgpu)	Unified memory, triple buffering
Linux	Vulkan (via wgpu)	Low overhead, explicit control
Windows	DirectX 12 (via wgpu)	Native Windows compositor

One wgpu codebase renders everywhere. No separate Metal/OpenGL backends like Ghostty.

3. SIMD-Optimized ANSI Parser

The VT100/ANSI parser uses memchr for bulk ESC byte scanning — a SIMD-accelerated search that skips large text runs without per-byte dispatch.

4. GPU-First Architecture

Component	Traditional Terminal	Spectral
Font rasterization	CPU (FreeType)	CPU initial cache, GPU rendering
Text rendering	Per-glyph draw calls	Single instanced draw (6 vertices × N cells)
Background	CPU compositing	GPU instanced colored quads
Frame pacing	VSync blocked	PresentMode::AutoNoVsync, 1-frame latency

5. Zero System Dependencies for Font Discovery

Unlike Ghostty/Alacritty which require fontconfig/pkg-config on Linux, Spectral uses fontdue (pure Rust) + manual font file scanning. No apt install fontconfig-dev needed.

Architecture

spectral/
├── spectral-core/          # Terminal grid, ANSI parser, damage tracking
├── spectral-font/          # Font loading, MSDF atlas, metrics
├── spectral-render/        # wgpu GPU renderer
├── spectral-pty/           # PTY abstraction
└── src/main.rs             # winit window + event loop

Build

# Requires: Rust 1.75+, a Vulkan/Metal/DX12 capable GPU
cargo build --release

Performance Targets

Benchmark	Kitty	Ghostty	Alacritty	Spectral Target
cat /dev/urandom	121 MB/s	~90 MB/s	43 MB/s	>150 MB/s
Key-to-screen latency	~8ms	~8ms	~10ms	<8ms
Startup time	~200ms	~150ms	~120ms	<100ms

License

MIT/Apache-2.0 dual license.