Vector subtraction

As with adding vectors, subtracting vectors is also a component-wise operation. You can think of subtracting vectors as adding the negative of the second vector to the first vector. When visualized as an arrow, subtraction points from the tip of the second vector to the tip of the first one.

To visually subtract vectors, place both vectors so they share the same origin. Draw a vector from the tip of the second arrow to the tip of the first one. The resulting arrow is the subtraction result vector:

Figure 2.3: Vector subtraction

To implement vector subtraction, subtract like components. Implement the subtraction function by overloading the - operator in vec3.cpp. Don't forget to add the function declaration to vec3.h:

vec3 operator-(const vec3 &l, const vec3 &r) {

    return vec3(l.x - r.x, l.y - r.y, l.z - r.z);

}

The steps and logic are very similar to vector addition. It might help to think of vector subtraction as adding a negative vector.