rayos

Implementation of several raytracing algorithms

Project structure

The project uses the file structure described in the following web page and the Makefile is a standard Unix Makefile: https://hiltmon.com/blog/2015/09/28/the-simple-c-plus-plus-makefile-executable-edition/

Executable

The build process generates an executable called "rayos" in the "bin" folder. This executable is called with the following arguments:

• Tracing Algorithm
  • w: Turner Whitted Raytracer
  • s: Stochastic Raytracer
• Number of sample rays (ignored if Whitted raytracer is used)
• Number of shadow rays (ignored if Whitted raytracer is used)

The program instantiates a Scene and the calls the raytracer trace method passing the scene as the parameter.

The trace method returns a Bitmap object that is then written to a TGA file. Finally the file is opened using the operating system tools.

Raytracing algorithms

The raytracing algorithms WhittedRayTracer and StochasticRayTracer extends the abstract Tracerclass. This class only implement the base constructors and the getHitPoint method.

ToDo: Implement indirect lighting for the StochasticRayTracer

The Tracer class initializes the BRDF object and the random number generator. There are several random number generators in the util folder.

Materials & BRDF

A Material is defined by:

• Color
• Ambient component (ka)
• Diffuse component (kd)
• Specular component (ks)

The BRDF (Bidirectional Reflectance Distribution Functions) calculates the radiance for each pixel in the scene by using the normal to the object in the hitpoint, the vector to the light, the vector to the viewer, and the material properties.

Currently the application supports only the PhongBRDF.

ToDo: Implement Blinn BRDF

Primitives

A Primitive has an objectType and a material. All the primitives extend the abstract Primitive class and need to implement the copy constructor, the destructor and the intersect methods.

Currently the application supports spheres, triangles and quads.

Scenes

An Scene includes the following elements:

• A collection of lights
• A collection of objects: lights and primitives
• A camera

ToDo: Read a scene from a 3D file format

Lights

A Light has a color and an intensity. It can be sampled to get a point using the getSamplePoint method. The application supports two different types of lights, that extend the abstract Light class:

• PointLight. Returns always the same sample point.
• RectLight. Area light.

Camera

A Camera is defined using the following parameters:

• location. Camera location
• view. Look-At Point
• up. Orientation
• distance. Distance to viewplane
• hFov, vFov. Horizontal and Vertical Field of View
• xRes, yRes. Viewplane resolution (image size)
• xCam, yCam, zCam. Camera coordinate system
• oViewport. Viewplane viewport origin
• uViewport, vViewport. Viewplane viewport axes
• pixelWidth, pixelHeight. Pixel dimensions

There is a getEyeRay method for getting an eye ray for non-stochastic algorithms and a getSampleEyeRays method for stochastic algorithms.

ToDo

• Include the light as a visible object (white)
• Improve performance using a space partitioning technique like Bounding Volume Hierarchies
• Read the scene data from glTF format using https://github.com/syoyo/tinygltf
• Read the scene data from PBRT format using https://github.com/ingowald/pbrt-parser
• Implement Blinn BRDF
• Implement indirect lighting for the StochasticRayTracer