In which you learn how to grow and shrink an object through vector multiplication.

To scale an object, you multiply its position by scale factors. A factor greater than 1 will grow the object. A factor less than 1 but greater than 0 will shrink an object. A factor of 0 will collapse an object into a black hole. A negative factor will flip an object.

Scaling is sometimes expressed as vector multiplication. Here position \(p\) is multiplied by \(\textrm{factors}\):

$$ \begin{bmatrix}p_x \\ p_y \\ p_z \end{bmatrix} \times \begin{bmatrix} \textrm{factors}_x \\ \textrm{factors}_y \\ \textrm{factors}_z \end{bmatrix} = \begin{bmatrix}p_x \times \textrm{factors}_x \\ p_y \times \textrm{factors}_y \\ p_z \times \textrm{factors}_z\end{bmatrix} $$

In GLSL, the factors are declared as a uniform and applied using the * operator:

uniform vec3 factors;
in vec3 position;

void main() {
  vec3 scaledPosition = position * factors;
  gl_Position = vec4(scaledPosition, 1.0);

Try adding scaling to one of your renderers.