physicsEngine

A minimal educational ray casting / shading sandbox in Rust. Renders a single Phong-lit sphere to both a window (via winit + pixels) and a saved PNG (render.png). Useful as a starter for learning:

• Screen-to-ray generation (pinhole camera)
• Ray vs sphere intersection
• Surface normal computation
• Basic Phong illumination (ambient + diffuse + specular)
• CPU raster loop -> GPU blit (using pixels)
• Saving raw RGBA buffer to disk (using image crate)

Current Features

• Single sphere primitive
• Point light with Phong shading
• Blue material (customizable in camera.rs)
• Specular highlight (adjust shininess for gloss)
• Image export on startup (render.png)
• Continuous or single-frame render structure (currently single-frame)

Render Preview

The image produced on launch (example):

If the highlight looks misplaced, ensure FOV is treated as degrees and converted to radians (already fixed) and that view & light vectors use point->camera / point->light directions.

Coordinate System

• Right-handed
• Camera looks down +Z
• +Y is up (after vertical flip when mapping pixels)
• Normal = (hit_point - sphere_center).normalized()

Project Structure

src/
  main.rs        # App + window lifecycle
  camera.rs      # Ray generation + shading loop
  sphere.rs      # Sphere primitive + intersection
  ray.rs         # Ray struct
  phong.rs       # Phong shading function
  light.rs       # Point light
  color.rs       # Color math & clamping
  vec3.rs        # 3D vector math
render.png       # Output image (overwritten on each run)

Build & Run

Prerequisites: Rust (stable toolchain)

cargo run

This will:

1. Open a 500x500 window displaying the rendered sphere.
2. Write render.png into the project root.

Run tests:

cargo test

Adjusting the Scene

Edit in main.rs:

• Sphere radius / position
• Light position / color
• Camera FOV & resolution

Shading tweaks in camera.rs (material colors, shininess).

Extending Ideas

• Multiple spheres (store a Vec)
• Shadows (shoot shadow ray toward light)
• Reflections (recursive rays)
• Simple BVH for acceleration
• Gamma correction before writing pixels

Known Simplifications

• No anti-aliasing
• No tone mapping / gamma pass
• No acceleration structure
• Single light source

License

Add a license of your choice (e.g. MIT/Apache-2.0) if you plan to publish.

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Minimal, clear, and hackable—ideal as a base for further ray tracing experiments.