How to change the Speed on vgNavigator Control Point

#include "vg.h" // Required for the standard Vega classes
#include "vgutil.h"

void

setNavigatorOverallSpeed( const int navIdx,

const float speed ){

// ##################################################

// # Public Function

// #

// # This function shows how to set a constant speed

// # on for the Navigator on all it velocitcy control

// # markers

// #

// ##################################################

char data[256];

unsigned ctrlptIdx = -1;

int eventType = -1;

double value = -1;

unsigned nbytes = 0;

// Sanity check we need the indexed navigator

vgSplineNavigator *navigator = vgGetNavigator( navIdx );

if( navigator == NULL )

return;

// Retrieve the current rendering state

int render = vgProp( navigator, VGSPLINENAV_RENDER );

// Retrieve the current navigator state

int navstate = vgProp( navigator, VGCOMMON_ENABLED );

// First switch the navigator and rendering off

// off because we may need a rebuild and the

// rendering is not multibuffered and can crash

vgProp( navigator, VGSPLINENAV_RENDER, VG_OFF );

vgProp( navigator, VGCOMMON_ENABLED, VG_OFF );

// Force an update of the navigators state

vgUpdate( navigator );

// Retrieve how many markers the navigator has

int numMarkers = vgGetProp( navigator,VGNAV_NUM_MARKERS);

// Unfortunately we have to search through every marker

// that the Navigator has to find the Velocity marker

// for the control point as Vega does not provide a

// a straight forward interface to do this

for( int j = 0; j < numMarkers; j++ ){

vgNavigatorGetMarker( (vgNavigator*)navigator,

&ctrlptIdx,

&eventType,

&value,

(void**)data,

&nbytes );

// If the marker is the type Velocity

if( eventType == VGSPLINENAV_VELOCITY ) {

// Now we can set the Velocity marker to the new speed

vgNavigatorMarker( (vgNavigator*)navigator,

ctrlptIdx,

VGSPLINENAV_VELOCITY,

speed,

NULL, 0 );

}

// We also need to set the default overal speed

vgProp( navigator,VGSPLINENAV_VELOCITY, speed );

// We need to call make after changes to markers

vgMakeSplineNavigator(navigator);

// Set the path render state back to its original state

if( render == VG_ON )

vgProp( navigator, VGSPLINENAV_RENDER, VG_ON );

// Set the path render state back to its original state

if( navstate == VG_ON )

vgProp( navigator, VGCOMMON_ENABLED, VG_ON );

} // setNavigatorOverallSpeed

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