Creating a matrix

In this section, you will create a new 4 x 4 matrix. This matrix will be stored as a 16-element array of floats. A union will be used to allow access to the data in the matrix in an easier-to-use fashion:

Important note

The identity matrix is a special matrix that multiplies anything by the identity matrix results in the original matrix. The identity matrix does no mapping. An identity matrix contains 0 in all elements except the main diagonal, which is made up entirely of 1.

1. Create a new file, mat4.h. This file is needed to declare the mat4 struct.
2. Add the following structure declaration to mat4.h, which starts a union by declaring a flat array of 16 elements as the first member of the union:

   struct mat4 {
       union {
           float v[16];

3. The next member of the union is a structure of vec4 variables. Each of the vec4 variables represents one column of the matrix; they are named after...