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# GoRayTracer
CPU ray tracer in Go — a port of Peter Shirley's *Ray Tracing in One Weekend*. Renders spheres with material scattering and outputs a PNG.
## What it does
- **Geometry:** `Vec3D`/`Ray`, `Sphere` + `HitableList` (closest-hit search) — `hitable.go:19`, `camera.go:12`
- **Camera:** pinhole with vertical FOV (90° by default) and aspect ratio — `camera.go:12`
- **Materials:** `Lambertian` (diffuse), `Metal` (fuzzed reflection), `Dielectric` (glass, Schlick approximation) — `material.go:13`
- **Rendering:** recursive `RayColor` with `MaxDepth=50`, `RaysPerPixel=10` stochastic anti-aliasing, gamma correction (`sqrt`) — `color.go:34`
- **Output:** `Frame [1000][2000]Pixel` sky gradient background, saved as PNG via `image/png` — `image.go:19`
Default scene (`main.go:35`): two `Lambertian` spheres (blue/red, radius `cos(π/4)`). Two alternative scenes are commented in `main.go:40` (metal/glass + ground sphere, and an animation loop).
Constants in `main.go:11`: `Width=2000`, `Height=1000`, `TMin=0.001`, `TMax=1000`, `RaysPerPixel=10`, `MaxDepth=50`.
## How to run
Prerequisite: [mise](https://mise.jdx.dev/) (installs Go automatically) or Go 1.27+.
```sh
# with mise (recommended)
mise install # installs Go 1.27
mise run run # go run . → writes img.png (~5s, 2000×1000)
mise run build # builds ./goraytracer
./goraytracer # same as above
# with Go directly
go mod tidy
go run . # → img.png
go build -o goraytracer . && ./goraytracer
```
Output is `img.png` (2000×1000 PNG, excluded by `.gitignore`). Check/lint:
```sh
mise run check # go fmt + go fix -diff + go vet + go build
```
## Customizing
Edit `main.go` to swap the `World` definition (uncomment the 4-sphere or animation blocks), or adjust `Width`/`Height`/`RaysPerPixel` for faster previews (e.g. 400×200).
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