The Ray Tracer Challenge

Multiplying Matrices

Multiplication is the tool you’ll use to perform transformations like scaling, rotation, and translation. It’s certainly possible to apply them one at a time, sequentially, but in practice you’ll often want to apply several transformations at once. Multiplying them together is how you make that happen, as you’ll see when you get to Chapter 4, ​Matrix Transformations​.

So let’s talk about matrix multiplication. It takes two matrices and produces another matrix by multiplying their component elements together in a specific way. You’ll see how that works shortly, but start first by writing a test that describes what you expect to happen when you multiply two 4x4 matrices together. Don’t worry about 2x2 or 3x3 matrices here; ...