//---------------------------------------------------------------------------

//

//  File: OpenGLRotation.m

//

//  Abstract: OpenGL class for managing a 3D objects rotation.

//           

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//

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#import "OpenGLRotation.h"

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Constants

//---------------------------------------------------------------------------

static const GLdouble kRotationFrequency = 30.0;

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Data Structures

//---------------------------------------------------------------------------

struct OpenGLRotationData

{

    GLfloat   roll;

    GLfloat   pitch;

    GLdouble  time;

    GLdouble  frequency;

};

typedef struct OpenGLRotationData  OpenGLRotationData;

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Constructor

//---------------------------------------------------------------------------

static OpenGLRotationDataRef OpenGLRotationCreate(const GLdouble frequency)

{

    OpenGLRotationDataRef pRotation = (OpenGLRotationDataRef)calloc(1, sizeof(OpenGLRotationData));

    if( pRotation != NULL )

    {

        pRotation->time  = -1.0f;

        pRotation->roll  =  0.0f;

        pRotation->pitch =  0.0f;

        pRotation->frequency = frequency;

    } // if

    else

    {

        NSLog( @">> ERROR: OpenGL Rotation - Allocating Memory For OpenGL Rotation Data Failed!" );

    } // else

    return( pRotation );

} // init

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Destructor

//---------------------------------------------------------------------------

static void OpenGLRotationDelete(OpenGLRotationDataRef pRotation) 

{

    if( pRotation != NULL )

    {

        free( pRotation );

        pRotation = NULL;

    } // if

} // OpenGLRotationDelete

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Utilties

//---------------------------------------------------------------------------

static GLdouble OpenGLRotationUpdateTime(OpenGLRotationDataRef pRotation) 

{

    GLdouble  timeDelta = 0.0;

    GLdouble  timeNow   = (GLdouble)[NSDate timeIntervalSinceReferenceDate];

    if( pRotation->time < 0 )

    {

        timeDelta = 0;

    } // if

    else

    {

        timeDelta = timeNow - pRotation->time;

    } // else

    pRotation->time = timeNow;

    return( timeDelta );

} // OpenGLRotationUpdateTime

//------------------------------------------------------------------------

static void OpenGLRotationUpdatePitch(OpenGLRotationDataRef pRotation) 

{

    if( pRotation->pitch < -45.0f )

    {

        pRotation->pitch = -45.0f;

    } // if

    else if( pRotation->pitch > 90.0f )

    {

        pRotation->pitch = 90.0f;

    } // else if

    glRotatef( pRotation->pitch, 1.0f, 0.0f, 0.0f );

} // OpenGLRotationUpdatePitch

//------------------------------------------------------------------------

static void OpenGLRotationUpdateRoll(OpenGLRotationDataRef pRotation) 

{

    GLdouble timeDelta = OpenGLRotationUpdateTime(pRotation);

    pRotation->roll += pRotation->frequency * timeDelta;

    if( pRotation->roll >= 360.0f )

    {

        pRotation->roll -= 360.0f;

    } // if

    glRotatef( pRotation->roll, 0.0f, 1.0f, 0.0f );

    // Increment the mpRotation angle

    pRotation->roll += 0.2f;

} // OpenGLRotationUpdateRoll

//------------------------------------------------------------------------

static void OpenGLRotationUpdate(OpenGLRotationDataRef pRotation) 

{

    OpenGLRotationUpdatePitch(pRotation);

    OpenGLRotationUpdateRoll(pRotation);

} // OpenGLRotationUpdate

//------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Private - Accessors

//---------------------------------------------------------------------------

static inline void OpenGLRotationSetFrequency(const GLdouble frequency,

                                              OpenGLRotationDataRef pRotation)

{

    pRotation->frequency = (frequency > 0.0) ? frequency : kRotationFrequency;

} // OpenGLRotationSetFrequency

//------------------------------------------------------------------------

static inline void OpenGLRotationSetRotation(const NSPoint *pEndPoint,

                                             const NSPoint *pStartPoint,

                                             OpenGLRotationDataRef pRotation)                                            

{

    if( (pEndPoint != NULL) && (pStartPoint != NULL) )

    {

        pRotation->roll  -= pEndPoint->x - pStartPoint->x;

        pRotation->pitch += pEndPoint->y - pStartPoint->y;

    } // if

} // OpenGLRotationSetRotation

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

//---------------------------------------------------------------------------

@implementation OpenGLRotation

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Public - Designated Initializer

//---------------------------------------------------------------------------

- (id) init

{

    self = [super init];

    if( self )

    {

        mpRotation = OpenGLRotationCreate(kRotationFrequency);

    } // if

    return( self );

} // init

//---------------------------------------------------------------------------

- (id) initRotationWithFrequency:(const GLdouble)theFrequency

{

    self = [super init];

    if( self )

    {

        mpRotation = OpenGLRotationCreate(theFrequency);

    } // if

    return( self );

} // initRotationWithFrequency

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#pragma mark -

#pragma mark Public - Destructor

//---------------------------------------------------------------------------

- (void) dealloc 

{

    OpenGLRotationDelete(mpRotation);

    [super dealloc];

} // dealloc

//------------------------------------------------------------------------

//------------------------------------------------------------------------

#pragma mark -

#pragma mark Public - Utilities

//------------------------------------------------------------------------

- (void) update

{

    OpenGLRotationUpdate(mpRotation);

} // update

//------------------------------------------------------------------------

//------------------------------------------------------------------------

#pragma mark -

#pragma mark Public - Accessors

//------------------------------------------------------------------------

- (void) setFrequency:(const GLdouble)theFrequency

{

    OpenGLRotationSetFrequency(theFrequency, mpRotation);

} // setFrequency

//------------------------------------------------------------------------

- (void) setRotation:(const NSPoint *)theEndPoint

               start:(const NSPoint *)theStartPoint

{

    OpenGLRotationSetRotation(theEndPoint, theStartPoint, mpRotation);

} // setPitch

//---------------------------------------------------------------------------

@end

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------