C++ Physically Based Ray-Tracing Engine

Overview

This project is a high-performance C++ ray-tracing engine designed to render complex 3D scenes with high fidelity. The engine utilizes OpenGL for the display pipeline and features a physically based rendering model that supports realistic lighting, hard and soft shadows, recursive reflections, and diverse material properties. It is optimized to handle scenes with significant geometric complexity through a hierarchical transformation stack.

Render Gallery

Below are examples of the engine's rendering capabilities, demonstrating the ability to handle high object counts and isolate specific lighting components.

Complex Scene Rendering

A "Thousand Spheres" stress test demonstrating depth, occlusion, and shadows across many instances.

Lighting Component Breakdown

The engine allows for the isolation of specific lighting contributions through its input configuration.

Component	Render	Description
Diffuse		Represents the matte surface color reflecting light based on the angle of incidence.
Specular		Isolates the shiny, reflective highlights determined by surface shininess.
Emission		Shows self-illuminating objects that glow independently of external light sources.
Ambient		Displays the constant base color applied to objects, simulating indirect lighting.

---

Features

• Physically Based Lighting: Calculates light interaction using Diffuse, Specular, Ambient, and Emission terms .
• Shadows & Reflections: Supports recursive ray tracing for accurate reflections (controlled by maxdepth) and shadow generation .
• Hierarchical Transformations: Implements a stack-based matrix system (pushTransform/popTransform) to render complex objects composed of multiple primitives .
• Custom Scene Description Language: Parses text-based input files to configure scene geometry, lights, and camera settings .

---

Scene Description Format (Input Guide)

The engine is driven by .txt input files. Below is a guide to the commands available for defining scene properties, derived from the project's test files.

1. Global Settings & Camera

Command	Arguments	Description
size	width height	Sets the output image resolution (e.g., 640 480) .
output	filename.png	Specifies the name of the file to save .
camera	ex ey ez lx ly lz ux uy uz fov	Defines the camera: Eye position, Look-at point, Up vector, and Field of View .
maxdepth	int	Sets the maximum recursion depth for rays (e.g., 5) .

2. Lighting & Materials

The engine uses a state-machine approach for materials; setting a property applies to all subsequent geometry until changed.

• Lights:

  • point x y z r g b: Defines a point light source at a specific position with a color intensity .
  • directional x y z r g b: Defines a directional light (like the sun) with a direction vector and color intensity .

• Material Properties:

  • ambient r g b: Sets the constant background illumination color .
  • diffuse r g b: Sets the matte surface color .
  • specular r g b: Sets the reflective highlight color .
  • shininess s: Sets the exponent for the specular highlight (higher = smaller, sharper highlight) .
  • emission r g b: Sets the self-glow color .

3. Geometry & Transforms

Objects are defined within a transformation stack to allow for relative positioning.

• Transforms:

  • translate x y z: Moves the current coordinate system .
  • rotate x y z degrees: Rotates the coordinate system .
  • scale x y z: Scales the coordinate system .
  • pushTransform: Saves the current transformation matrix to the stack .
  • popTransform: Restores the previous transformation matrix .

• Primitives:

  • sphere x y z radius: Renders a sphere at the given coordinates .
  • vertex x y z: Defines a vertex for a polygon .
  • tri v1 v2 v3: Creates a triangle using indices of previously defined vertices .

Example Scene Configuration

The following snippet demonstrates how a scene is constructed using the input format:

# Camera and Output setup
size 640 480 
output scene4-specular.png
camera 0 -4 4 0 -1 0 0 1 1 45

# Lighting setup
point 1 1 3 1 1 1

# Material setup (Specular Example)
ambient 0 0 0
diffuse 0 0 0
specular .6 .6 .5
shininess 20

# Geometry definition with Transforms
pushTransform
  scale 2 1 .25
  # (Triangle definitions omitted for brevity)
popTransform