# 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**.

```ini
# 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

```bash
# 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.