File indexing completed on 2024-05-12 04:05:52

 /** KempoApi: The Turloc Toolkit *****************************/
 /** *    *                                                  **/
 /** **  **  Filename: ArcBall.cpp                           **/
 /**   **    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  **/
 /**                                                         **/
 /*************************************************************/
 
 #include "ArcBall.h"                                            // ArcBall header
 
 #include <cstdio>
 
 //Arcball sphere constants:
 //Diameter is       2.0f
 //Radius is         1.0f
 //Radius squared is 1.0f
 
 void ArcBall_t::_mapToSphere(const Point2fT* NewPt, Vector3fT* NewVec) const
 {
     Point2fT TempPt;
     GLfloat length;
 
     //Copy parameter into temp point
     TempPt = *NewPt;
 
     //Adjust point coords and scale down to range of [-1 ... 1]
     TempPt.s.X  =        (TempPt.s.X * this->AdjustWidth)  - 1.0f;
     TempPt.s.Y  = 1.0f - (TempPt.s.Y * this->AdjustHeight);
 
     //Compute the square of the length of the vector to the point from the center
     length      = (TempPt.s.X * TempPt.s.X) + (TempPt.s.Y * TempPt.s.Y);
 
     //If the point is mapped outside of the sphere... (length > radius squared)
     if (length > 1.0f)
     {
         GLfloat norm;
 
         //Compute a normalizing factor (radius / sqrt(length))
         norm    = 1.0f / FuncSqrt(length);
 
         //Return the "normalized" vector, a point on the sphere
         NewVec->s.X = TempPt.s.X * norm;
         NewVec->s.Y = TempPt.s.Y * norm;
         NewVec->s.Z = 0.0f;
     }
     else    //Else it's on the inside
     {
         //Return a vector to a point mapped inside the sphere sqrt(radius squared - length)
         NewVec->s.X = TempPt.s.X;
         NewVec->s.Y = TempPt.s.Y;
         NewVec->s.Z = FuncSqrt(1.0f - length);
     }
 }
 
 //Create/Destroy
 ArcBall_t::ArcBall_t(GLfloat NewWidth, GLfloat NewHeight)
 {
     //Clear initial values
     this->StVec.s.X     =
     this->StVec.s.Y     = 
     this->StVec.s.Z     = 
 
     this->EnVec.s.X     =
     this->EnVec.s.Y     = 
     this->EnVec.s.Z     = 0.0f;
 
     //Set initial bounds
     this->setBounds(NewWidth, NewHeight);
 }
 
 //Mouse down
 void    ArcBall_t::click(const Point2fT* NewPt)
 {
     //Map the point to the sphere
     this->_mapToSphere(NewPt, &this->StVec);
 }
 
 //Mouse drag, calculate rotation
 void    ArcBall_t::drag(const Point2fT* NewPt, Quat4fT* NewRot)
 {
     //Map the point to the sphere
     this->_mapToSphere(NewPt, &this->EnVec);
 
     //Return the quaternion equivalent to the rotation
     if (NewRot)
     {
         Vector3fT  Perp;
 
         //Compute the vector perpendicular to the begin and end vectors
         Vector3fCross(&Perp, &this->StVec, &this->EnVec);
 
         //Compute the length of the perpendicular vector
         if (Vector3fLength(&Perp) > Epsilon)    //if its non-zero
         {
             //We're ok, so return the perpendicular vector as the transform after all
             NewRot->s.X = Perp.s.X;
             NewRot->s.Y = Perp.s.Y;
             NewRot->s.Z = Perp.s.Z;
             //In the quaternion values, w is cosine (theta / 2), where theta is rotation angle
             NewRot->s.W= Vector3fDot(&this->StVec, &this->EnVec);
         }
         else                                    //if its zero
         {
             //The begin and end vectors coincide, so return an identity transform
             NewRot->s.X = 
             NewRot->s.Y = 
             NewRot->s.Z = 
             NewRot->s.W = 0.0f;
         }
     }
 }