OpenGL Camera by Ozwald

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class glCamera {     public:     GLfloat    m_MaxPitchRate, m_MaxHeadingRate,             m_HeadingDegrees, m_PitchDegrees,             m_MaxForwardVelocity, m_ForwardVelocity;                  glQuaternion m_qHeading, m_qPitch;     glPoint m_Position;     fvector3 m_DirectionVector;     fvector3 target;          void ChangeVelocity( GLfloat vel );     void ChangeHeading( GLfloat degrees );     void ChangePitch( GLfloat degrees );     void Shuffle( GLfloat speed );     glCamera();     virtual ~glCamera(); }; // --------- glCamera::glCamera() {     m_MaxPitchRate            = 1.0f;     m_MaxHeadingRate        = 1.0f;     m_HeadingDegrees        = 0.0f;     m_PitchDegrees            = 0.0f;     m_MaxForwardVelocity    = 0.1f;     m_ForwardVelocity        = 0.0f;          m_Position.y = 1.0f; } glCamera::~glCamera() {    } void glCamera::SetPerspective() {     GLfloat Matrix[16];     glQuaternion q;          m_qPitch.CreateFromAxisAngle    ( 1.0f, 0.0f, 0.0f, m_PitchDegrees );     //m_qPitch.CreateFromAxisAngle    ( 1.0f, 0.0f, 0.0f, 0.0f );     m_qHeading.CreateFromAxisAngle    ( 0.0f, 1.0f, 0.0f, m_HeadingDegrees );          q = m_qPitch * m_qHeading;     q.CreateMatrix( Matrix );          glMultMatrixf( Matrix );          m_qPitch.CreateMatrix( Matrix );     m_DirectionVector.y = Matrix[9];          q = m_qHeading * m_qPitch;     q.CreateMatrix( Matrix );     m_DirectionVector.x = Matrix[8];     m_DirectionVector.z = Matrix[10];          m_DirectionVector = m_DirectionVector * m_ForwardVelocity;          m_Position.x += m_DirectionVector.x;     //m_Position.y += m_DirectionVector.y;    // this is what makes us fly around up&down     m_Position.z += m_DirectionVector.z;          gluLookat( -m_Position.x, -m_Position.y, -m_Position.z, target.x, target.y, target.z, m_PitchDegrees, m_HeadingDegrees, 0.0f ); } void glCamera::ChangePitch( GLfloat degrees ) {     if( fabs(degrees) < fabs(m_MaxPitchRate) ) {         m_PitchDegrees += degrees;     } else {         if( degrees < 0 ) {             m_PitchDegrees -= m_MaxPitchRate;         } else {             m_PitchDegrees += m_MaxPitchRate;         }     }          if( m_PitchDegrees > 360.0f ) {         m_PitchDegrees -= 360.0f;     } else if(m_PitchDegrees < -360.0f ) {         m_PitchDegrees += 360.0f;     } } void glCamera::ChangeHeading( GLfloat degrees ) {     if( fabs(degrees) < fabs(m_MaxHeadingRate) ) {         if( m_PitchDegrees > 90 && m_PitchDegrees < 270 || (m_PitchDegrees < -90 && m_PitchDegrees > -270) ) {             m_HeadingDegrees -= degrees;         } else {             m_HeadingDegrees += degrees;         }     } else {         if( degrees < 0 ) {             if( m_PitchDegrees > 90 && m_PitchDegrees < 270 || (m_PitchDegrees < -90 && m_PitchDegrees > -270) ) {                 m_HeadingDegrees += m_MaxHeadingRate;             } else {                 m_HeadingDegrees -= m_MaxHeadingRate;             }         } else {             if( m_PitchDegrees > 90 && m_PitchDegrees < 270 || (m_PitchDegrees < -90 && m_PitchDegrees > -270) ) {                 m_HeadingDegrees -= m_MaxHeadingRate;             } else {                 m_HeadingDegrees += m_MaxHeadingRate;             }         }     }          if( m_HeadingDegrees > 360.0f ) {         m_HeadingDegrees -= 360.0f;     } else if( m_HeadingDegrees < -360.0f ) {         m_HeadingDegrees += 360.0f;     } } void glCamera::ChangeVelocity( GLfloat vel ) {     if( fabs(vel) < fabs(m_MaxForwardVelocity) ) {         m_ForwardVelocity += vel;     } else {         if( vel < 0 ) {             m_ForwardVelocity -= -m_MaxForwardVelocity;         } else {             m_ForwardVelocity += m_MaxForwardVelocity;         }     } } void glCamera::Shuffle( GLfloat speed ) {     GLfloat Matrix[16];     glQuaternion q;          m_qPitch.CreateFromAxisAngle    ( 1.0f, 0.0f, 0.0f, m_PitchDegrees );     //m_qPitch.CreateFromAxisAngle    ( 1.0f, 0.0f, 0.0f, 0.0f );     m_qHeading.CreateFromAxisAngle    ( 0.0f, 1.0f, 0.0f, m_HeadingDegrees + 90.0f );          q = m_qPitch * m_qHeading;     q.CreateMatrix( Matrix );          glMultMatrixf( Matrix );          m_qPitch.CreateMatrix( Matrix );     m_DirectionVector.y = Matrix[9];          q = m_qHeading * m_qPitch;     q.CreateMatrix( Matrix );     m_DirectionVector.x = Matrix[8];     m_DirectionVector.z = Matrix[10];          m_DirectionVector = m_DirectionVector * speed;          m_Position.x += m_DirectionVector.x;     //m_Position.y += m_DirectionVector.y;    // this is what makes us fly around up&down     m_Position.z += m_DirectionVector.z; }