vec4 operator-(vec4 left, const vec4& right) { return left.subtract(right); }
vec4 operator-(vec4 vector, const vec4& other_vector) { return vector.subtract(other_vector); }
vec4 operator-(vec4 left, const vec4& right) { return left.subtract(right); }
vec4 operator-(vec4 vector, const vec4& other_vector) { return vector.subtract(other_vector); }