Lab 4: Implementing Diffuse Shading Solution

Introduction




The purpose of this lab is to continue building our ray tracer by adding diffuse

shading and directional lighting as discussed in the lectures. We will also

discuss the way the code will be designed, as well as setup the basic interfaces

that future classes will be based on. Note that the lab uses random and regular

sampling, which may not be ideal for this type of rendering.




Ray Tracer Design




This lab uses most of the infrastructure code from Lab 3, with the exception of

the cameras. In this lab you'll be responsible for implementing the following

classes:




1. The `BRDF` class,

2. the `Material` class,

3. the `Light` class.




The three classes above are provided as interfaces in the `lab.hpp` file. Along

with implementing the non-virtual member functions of the three interfaces, you

must implement concrete classes of the interfaces: `Lambertian`, `Matte`,

`Directional`, and `Ambient`. No new C++ content is covered in this lab.




Implementation




A number of the functions in the interfaces have parameters which are not required

for all implementations of the functions. For example, the `Lambertian::f` will

not require the `ShadeRec` or `Vector` parameters. Visual Studio's compiler by default

will treat unused parameters as errors, to avoid this in the implementation of the

function add the compiler pragma `[[maybe_unused]]` in front of each unused parameter.




The `shade` function of the `Material` is where the `BRDF` and `Light` functions come

together to create the shaded color of the surface. In the Lab 3 the average pixel

color was taken directly from the `ShadeRec`. When taking into account directional

lighting and material the sampling step should instead pass the `ShadeRec` to the

`shade` function of the hit material to determine the color to be added to the accumulator.




With the ray tracer created in this lab, you will be able to render scenes with

simple lighting like the render below: