math for some vector operations

//Author JP.LEE  AUG. 2013

#define  VECTOR3_H

#include <math .h="">

class Vector3
{
public:
 Vector3(float X = 0.0f , float Y = 0.0f , float Z = 0.0f)
 {
  x = X;
  y = Y;
  z = Z;
 }

Vector3 operator+=(const Vector3 &vec)
 {
  return (*this = (*this + vec));
 }

Vector3 operator+(const Vector3 &vec)//백터플러스 오퍼레이터.
 {
  return Vector3(vec.x + x , vec.y + y, vec.z + z);
 }

Vector3 operator-=(const Vector3 &vec)//마이너스 이퀄 오퍼레이터.
 {
  return (*this = (*this - vec));
 }

Vector3 operator-(const Vector3 &vec )
 {
  return Vector3( x - vec.x , y - vec.y,  z - vec.z );
 }

Vector3 operator*=(float num )
 {
  return ( *this = ( *this * num ) );
 }

Vector3 operator * (float num)
 {
  return Vector3( x * num,  y * num,  z * num);
 }

Vector3 operator /=(float num )
 {
  return ( *this = ( *this * num ) );
 }

Vector3 operator / (float num)
 {
  return Vector3( x / num,  y / num,  z / num);
 }
 Vector3 operator -(void)
 {
  return Vector3(x, -y, -z);
 }

float Dot(Vector3 &vec)
 {
  return ( x * vec.x + y * vec.y + z  * vec.z);
 }

Vector3 operator*(const Vector3 &vec)
 {
  return Vector3 ( y * vec.z - z * vec.y,
   z * vec.x - x * vec.z,
   x * vec.y - y * vec.x );
 }

Vector3 Normalize(void)
 {
  float length = Length();
  x /= length;
  y /= length;
  z /= length;

return *this;
 }

float Distance(Vector3 &vec)
 {
  float disX = vec.x - x;
  float disY = vec.y - y;
  float disZ = vec.z - z;

return sqrt(disX*disX + disY*disY + disZ*disZ);
 }

bool operator ==(Vector3 &vec)
 {
  return sqrt(vec.x == x && vec.y ==y  && vec.z==z);
 }

bool operator !=(Vector3 &vec)
 {
  return !(vec == *this);
 }

float Length(void)
 {
  return sqrt(x * x + y * y + z * z);
 }
public:
 float x , y , z;
 
};
  
}

Leegoonz game Developer blog.