reject method
Implementation
Vector3D reject(Vector3D o) {
final v1dv2 = (x*o.x + y*o.y + z*o.z);
final v2dv2 = (o.x*o.x + o.y*o.y + o.z*o.z);
final mag = v1dv2/v2dv2;
return .vec3(
x - (o.x*mag),
y - (o.y*mag),
z - (o.z*mag),
);
}