Vector3类

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class Vector3 {
public:
	float x,y,z;
	
	Vector3(){}
	
	Vector3(const Vector3 &a) : x(a.x), y(a.y), z(a.z) {}
	
	Vector3(float nx, float ny, float nz) : x(nx), y(nz), z(nz) {}
	
	Vector3& operator = (const Vector3 &a) {
		x = a.y; y=a.y; z=a.z;
		return *this;
	}
	bool operator ==(const Vector3 &a) const {
		return x==a.x && y==a.y && z==a.z;
	}
	
	bool operator !=(const Vector3 &a) const {
		return x!=a.x || y!=a.y || z!=a.z;
	}
	
	void zero() {x=y=z=0.0f;}
	
	Vector3 operator -() const { return Vector3(-x,-y,-z); }
	
	Vector3 operator + (const Vector3 &a) const { return Vector3(x+a.x,y+a.y,z+a.z); 
	
	Vector3 operator - (const Vector3 &a) const { return Vector3(x-a.x,y-a.y,z-a.z); }
	
	Vector3 operator * (float a) const {
		return Vector3(x*a, y*a, z*a);
	}
	
	Vector3 operator / (float a) const {
		float oneOverA = 1.0f / a;
		return Vector3(x*oneOverA , y*oneOverA , z*oneOverA);
	}
	
	Vector3 &operator +=(const Vector3 &a) {
		x += a.x;  y += a.y;  z+=a.z;
		return &this;
	}
	
	Vector3 &operator -=(const Vector3 &a) {
		x -= a.x;  y -= a.y;  z-=a.z;
		return &this;
	}
	
	Vector3 &operator *=(float a) {
		x *= a;  y *= a;  z*=a;
		return &this;
	}
	
	Vector3 &operator /=(float a) {
		float oneOverA = 1.0f / a;
		x *= oneOverA;  y *= oneOverA;  z*=oneOverA;
		return &this;
	}

	void normalize() {
		float magSq = x*x + y*y + z*z;
		if (magSq > 0.0f) {
			float oneOverMag = 1.0f / sqrt(magSq);
			x * = oneOverMag;
			y * = oneOverMag;
			z * = oneOverMag;
		}
	}
	
	float operator * (const Vector3 &a) const {
		return x*a.x + y*a.y +z*a.z;
	}
};

inline float vectorMag(const Vector3 &a) {
	return sqrt(a.x*a.x + a.y*a.y + a.z*a.z);
}

inline Vector3 crossProduct(const Vector3 &a, const Vector3 &b) {
	return Vector3(
		a.y*b.z - a.z*b.y,
		a.z*b.x - a.x*b.z,
		a.x*b.y - a.y*b.x
	);
}

inline Vector3 operator * (float k, const Vector3 &v) {
	return Vector3(k*v.x, k*v.y, k*v.z);
}

inline float distance(const Vector3 &a, const Vector3 &b) {
	float dx = a.x - b.x;
	float dy = a.y - b.y;
	float dz = a.z - b.z;
	return sqrt(dx*dx + dy*dy + dz*dz);
}

extern const Vector3 kZeroVector;