arcball.h

基于NEHE第48课的程序,改为MFC下运行.运用轨迹球技术,初学者值得参考

/** KempoApi: The Turloc Toolkit *****************************/
/** *    *                                                  **/
/** **  **  Filename: ArcBall.h                             **/
/**   **    Version:  Common                                **/
/**   **                                                    **/
/**                                                         **/
/**  Arcball class for mouse manipulation.                  **/
/**                                                         **/
/**                                                         **/
/**                                                         **/
/**                                                         **/
/**                              (C) 1999-2003 Tatewake.com **/
/**   History:                                              **/
/**   08/17/2003 - (TJG) - Creation                         **/
/**   09/23/2003 - (TJG) - Bug fix and optimization         **/
/**   09/25/2003 - (TJG) - Version for NeHe Basecode users  **/
/**                                                         **/
/*************************************************************/

#ifndef _ArcBall_h
#define _ArcBall_h

// 8<--Snip here if you have your own math types/funcs-->8 

//Only support assertions in debug builds
#ifdef _DEBUG
# include "assert.h"
#else
# define assert(x) { }
#endif

#include <cmath>




//Math types derived from the KempoApi tMath library
    typedef union Tuple2f_t
    {
        struct
        {
            GLfloat X, Y;
        } s;

        GLfloat T[2];
    } Tuple2fT;      //A generic 2-element tuple that is represented by single-precision floating point x,y coordinates. 

    typedef union Tuple3f_t
    {
        struct
        {
            GLfloat X, Y, Z;
        } s;

        GLfloat T[3];
    } Tuple3fT;      //A generic 3-element tuple that is represented by single precision-floating point x,y,z coordinates. 

    typedef union Tuple4f_t
    {
        struct
        {
            GLfloat X, Y, Z, W;
        } s;

        GLfloat T[4];
    } Tuple4fT;      //A 4-element tuple represented by single-precision floating point x,y,z,w coordinates. 

    typedef union Matrix3f_t
    {
            struct
            {
                //column major
                union { GLfloat M00; GLfloat XX; GLfloat SX; };  //XAxis.X and Scale X
                union { GLfloat M10; GLfloat XY;             };  //XAxis.Y
                union { GLfloat M20; GLfloat XZ;             };  //XAxis.Z
                union { GLfloat M01; GLfloat YX;             };  //YAxis.X
                union { GLfloat M11; GLfloat YY; GLfloat SY; };  //YAxis.Y and Scale Y
                union { GLfloat M21; GLfloat YZ;             };  //YAxis.Z
                union { GLfloat M02; GLfloat ZX;             };  //ZAxis.X
                union { GLfloat M12; GLfloat ZY;             };  //ZAxis.Y
                union { GLfloat M22; GLfloat ZZ; GLfloat SZ; };  //ZAxis.Z and Scale Z
            } s;
            GLfloat M[9];
    } Matrix3fT;     //A single precision floating point 3 by 3 matrix. 

    typedef union Matrix4f_t
    {
            struct
            {
                //column major
                union { GLfloat M00; GLfloat XX; GLfloat SX; };  //XAxis.X and Scale X
                union { GLfloat M10; GLfloat XY;             };  //XAxis.Y
                union { GLfloat M20; GLfloat XZ;             };  //XAxis.Z
                union { GLfloat M30; GLfloat XW;             };  //XAxis.W
                union { GLfloat M01; GLfloat YX;             };  //YAxis.X
                union { GLfloat M11; GLfloat YY; GLfloat SY; };  //YAxis.Y and Scale Y
                union { GLfloat M21; GLfloat YZ;             };  //YAxis.Z
                union { GLfloat M31; GLfloat YW;             };  //YAxis.W
                union { GLfloat M02; GLfloat ZX;             };  //ZAxis.X
                union { GLfloat M12; GLfloat ZY;             };  //ZAxis.Y
                union { GLfloat M22; GLfloat ZZ; GLfloat SZ; };  //ZAxis.Z and Scale Z
                union { GLfloat M32; GLfloat ZW;             };  //ZAxis.W
                union { GLfloat M03; GLfloat TX;             };  //Trans.X
                union { GLfloat M13; GLfloat TY;             };  //Trans.Y
                union { GLfloat M23; GLfloat TZ;             };  //Trans.Z
                union { GLfloat M33; GLfloat TW; GLfloat SW; };  //Trans.W and Scale W
            } s;
            GLfloat M[16];
    } Matrix4fT;     //A single precision floating point 4 by 4 matrix. 


//"Inherited" types
#define Point2fT    Tuple2fT   //A 2 element point that is represented by single precision floating point x,y coordinates. 

#define Quat4fT     Tuple4fT   //A 4 element unit quaternion represented by single precision floating point x,y,z,w coordinates. 

#define Vector2fT   Tuple2fT   //A 2-element vector that is represented by single-precision floating point x,y coordinates. 
#define Vector3fT   Tuple3fT   //A 3-element vector that is represented by single-precision floating point x,y,z coordinates. 

//Custom math, or speed overrides
#define FuncSqrt    sqrtf

//utility macros
//assuming IEEE-754(GLfloat), which i believe has max precision of 7 bits
# define Epsilon 1.0e-5

//Math functions

    /**
     * Sets the value of this tuple to the vector sum of itself and tuple t1.
     * @param t1  the other tuple
     */
    inline
    static void Point2fAdd(Point2fT* NewObj, const Tuple2fT* t1)
    {
        assert(NewObj && t1);

        NewObj->s.X += t1->s.X;
        NewObj->s.Y += t1->s.Y;
    }

    /**
      * Sets the value of this tuple to the vector difference of itself and tuple t1 (this = this - t1).
      * @param t1 the other tuple
      */
    inline
    static void Point2fSub(Point2fT* NewObj, const Tuple2fT* t1)
    {
        assert(NewObj && t1);

        NewObj->s.X -= t1->s.X;
        NewObj->s.Y -= t1->s.Y;
    }

    /**
      * Sets this vector to be the vector cross product of vectors v1 and v2.
      * @param v1 the first vector
      * @param v2 the second vector
      */
    inline
    static void Vector3fCross(Vector3fT* NewObj, const Vector3fT* v1, const Vector3fT* v2)
    {
        Vector3fT Result; //safe not to initialize

        assert(NewObj && v1 && v2);

        // store on stack once for aliasing-safty
        // i.e. safe when a.cross(a, b)

        Result.s.X = (v1->s.Y * v2->s.Z) - (v1->s.Z * v2->s.Y);
        Result.s.Y = (v1->s.Z * v2->s.X) - (v1->s.X * v2->s.Z);
        Result.s.Z = (v1->s.X * v2->s.Y) - (v1->s.Y * v2->s.X);

        //copy result back
        *NewObj = Result;
    }

    /**
      * Computes the dot product of the this vector and vector v1.
      * @param  v1 the other vector
      */
    inline
    static GLfloat Vector3fDot(const Vector3fT* NewObj, const Vector3fT* v1)
    {
        assert(NewObj && v1);

        return  (NewObj->s.X * v1->s.X) +
                (NewObj->s.Y * v1->s.Y) +
                (NewObj->s.Z * v1->s.Z);
    }

    /**
      * Returns the squared length of this vector.
      * @return the squared length of this vector
      */
    inline
    static GLfloat Vector3fLengthSquared(const Vector3fT* NewObj)
    {
        assert(NewObj);

        return  (NewObj->s.X * NewObj->s.X) +
                (NewObj->s.Y * NewObj->s.Y) +
                (NewObj->s.Z * NewObj->s.Z);
    }

    /**
      * Returns the length of this vector.
      * @return the length of this vector
      */
    inline
    static GLfloat Vector3fLength(const Vector3fT* NewObj)
    {
        assert(NewObj);

        return FuncSqrt(Vector3fLengthSquared(NewObj));
    }

    inline
    static void Matrix3fSetZero(Matrix3fT* NewObj)
    {
        NewObj->s.M00 = NewObj->s.M01 = NewObj->s.M02 = 
        NewObj->s.M10 = NewObj->s.M11 = NewObj->s.M12 = 
        NewObj->s.M20 = NewObj->s.M21 = NewObj->s.M22 = 0.0f;
    }

    /**
     * Sets this Matrix3 to identity.
     */
    inline
    static void Matrix3fSetIdentity(Matrix3fT* NewObj)
    {
        Matrix3fSetZero(NewObj);

        //then set diagonal as 1
        NewObj->s.M00 = 
        NewObj->s.M11 = 
        NewObj->s.M22 = 1.0f;
    }

    /**
      * Sets the value of this matrix to the matrix conversion of the