vector.h

一本关于OPenGL的很好的电子书

#ifndef __VECTOR_H
#define __VECTOR_H

#include <math.h>

/*
     VECTOR.H

     scalar_t
     CVector class

     OpenGL Game Programming
     by Kevin Hawkins and Dave Astle

     Some operators of the CVector class based on
     operators of the CVector class by Bas Kuenen.
     Copyright (c) 2000 Bas Kuenen. All Rights Reserved.
     homepage: baskuenen.cfxweb.net
*/

typedef float scalar_t;

class CVector
{
public:
     scalar_t x;
     scalar_t y;
     scalar_t z;    // x,y,z coordinates

public:
     CVector(scalar_t a = 0, scalar_t b = 0, scalar_t c = 0) : x(a), y(b), z(c) {}
     CVector(const CVector &vec) : x(vec.x), y(vec.y), z(vec.z) {}

     // vector assignment
     const CVector &operator=(const CVector &vec)
     {
          x = vec.x;
          y = vec.y;
          z = vec.z;

          return *this;
     }

     // vecector equality
     const bool operator==(const CVector &vec) const
     {
          return ((x == vec.x) && (y == vec.y) && (z == vec.z));
     }

     // vecector inequality
     const bool operator!=(const CVector &vec) const
     {
          return !(*this == vec);
     }

     // vector add
     const CVector operator+(const CVector &vec) const
     {
          return CVector(x + vec.x, y + vec.y, z + vec.z);
     }

     // vector add (opposite of negation)
     const CVector operator+() const
     {    
          return CVector(*this);
     }

     // vector increment
     const CVector& operator+=(const CVector& vec)
     {    x += vec.x;
          y += vec.y;
          z += vec.z;
          return *this;
     }

     // vector subtraction
     const CVector operator-(const CVector& vec) const
     {    
          return CVector(x - vec.x, y - vec.y, z - vec.z);
     }
     
     // vector negation
     const CVector operator-() const
     {    
          return CVector(-x, -y, -z);
     }

     // vector decrement
     const CVector &operator-=(const CVector& vec)
     {
          x -= vec.x;
          y -= vec.y;
          z -= vec.z;

          return *this;
     }

     // scalar self-multiply
     const CVector &operator*=(const scalar_t &s)
     {
          x *= s;
          y *= s;
          z *= s;
          
          return *this;
     }

     // scalar self-divecide
     const CVector &operator/=(const scalar_t &s)
     {
          const float recip = 1/s; // for speed, one divecision

          x *= recip;
          y *= recip;
          z *= recip;

          return *this;
     }

     // post multiply by scalar
     const CVector operator*(const scalar_t &s) const
     {
          return CVector(x*s, y*s, z*s);
     }

     // pre multiply by scalar
     friend inline const CVector operator*(const scalar_t &s, const CVector &vec)
     {
          return vec*s;
     }

/*   friend inline const CVector operator*(const CVector &vec, const scalar_t &s)
     {
          return CVector(vec.x*s, vec.y*s, vec.z*s);
     }

*/   // divecide by scalar
     const CVector operator/(scalar_t s) const
     {
          s = 1/s;

          return CVector(s*x, s*y, s*z);
     }

     // cross product
     const CVector CrossProduct(const CVector &vec) const
     {
          return CVector(y*vec.z - z*vec.y, z*vec.x - x*vec.z, x*vec.y - y*vec.x);
     }

     // cross product
     const CVector operator^(const CVector &vec) const
     {
          return CVector(y*vec.z - z*vec.y, z*vec.x - x*vec.z, x*vec.y - y*vec.x);
     }

     // dot product
     const scalar_t DotProduct(const CVector &vec) const
     {
          return x*vec.x + y*vec.x + z*vec.z;
     }

     // dot product
     const scalar_t operator%(const CVector &vec) const
     {
          return x*vec.x + y*vec.x + z*vec.z;
     }


     // length of vector
     const scalar_t Length() const
     {
          return (scalar_t)sqrt((double)(x*x + y*y + z*z));
     }

     // return the unit vector
     const CVector UnitVector() const
     {
          return (*this) / Length();
     }

     // normalize this vector
     void Normalize()
     {
          (*this) /= Length();
     }

     const scalar_t operator!() const
     {
          return sqrtf(x*x + y*y + z*z);
     }

     // return vector with specified length
     const CVector operator | (const scalar_t length) const
     {
          return *this * (length / !(*this));
     }

     // set length of vector equal to length
     const CVector& operator |= (const float length)
     {
          return *this = *this | length;
     }

     // return angle between two vectors
     const float inline Angle(const CVector& normal) const
     {
          return acosf(*this % normal);
     }

     // reflect this vector off surface with normal vector
     const CVector inline Reflection(const CVector& normal) const
     {    
          const CVector vec(*this | 1);     // normalize this vector
          return (vec - normal * 2.0 * (vec % normal)) * !*this;
     }

};

#endif