Data Structures
struct	GAZE_MOTION
	Gaze motion attributes velocity, acceleration for gaze, eye-in-head, head-in-space. Contains data specific to the EyeLink 3 that defaults to MISSING with preceding camera models. More...

Macros
#define	FIVE_SAMPLE_MODEL 1

#define	NINE_SAMPLE_MODEL 2

#define	SEVENTEEN_SAMPLE_MODEL 3

#define	EL1000_TRACKER_MODEL 4

Functions
int	eyelink_calculate_velocity_x_y (int slen, float xvel[2], float yvel[2], FSAMPLE *vel_sample)

int	eyelink_calculate_velocity (int slen, float vel[2], FSAMPLE *vel_sample)

int	eyelink_calculate_overallvelocity_and_acceleration (int slen, float vel[2], float acc[2], FSAMPLE *vel_sample)

int	eyelink_calculate_overallvelocity_and_acceleration2 (int slen, GAZE_MOTION gazeMotion, FSAMPLE2 vel_sample)

Detailed Description

Macro Definition Documentation

#define EL1000_TRACKER_MODEL 4

Compute velocity and acceleration from recent samples using the EyeLink 1000 model. Pass this to the slen parameter of eyelink_calculate_overallvelocity_and_acceleration2( ).

#define FIVE_SAMPLE_MODEL 1

Compute velocity and acceleration from the latest five contiguous samples. Pass this to the slen parameter of eyelink_calculate_overallvelocity_and_acceleration2( ).

#define NINE_SAMPLE_MODEL 2

Compute velocity and acceleration from the latest nine contiguous samples. Pass this to the slen parameter of eyelink_calculate_overallvelocity_and_acceleration2( ).

#define SEVENTEEN_SAMPLE_MODEL 3

Compute velocity and acceleration from the latest seventeen contiguous samples. Pass this to the slen parameter of eyelink_calculate_overallvelocity_and_acceleration2( ).

Function Documentation

int eyelink_calculate_overallvelocity_and_acceleration	(	int	slen,
		float	vel[2],
		float	acc[2],
		FSAMPLE *	vel_sample
	)

Calculates overall velocity and acceleration for left and right eyes separately.

Parameters

[in]	slen	Sample model to use for velocity calculation. Acceptable models are `FIVE_SAMPLE_MODEL`, `NINE_SAMPLE_MODEL`, `SEVENTEEN_SAMPLE_MODEL` and `EL1000_TRACKER_MODEL`.
[out]	vel	A float array of 2 to fill in the calculated velocity results. Upon return of this function, vel[0] will contain overall velocity for left eye and vel[1] will contain overall velocity for right eye. If velocity cannot be calculated for any reason(eg. insufficient samples, no data) MISSING_DATA is filled for the given velocity.
[out]	acc	A float array of 2 to fill in the calculated acceleration results. Upon return of this function, acc[0] will contain overall acceleration for left eye and acc[1] will contain overall acceleration for right eye. If acceleration cannot be calculated for any reason(eg. insufficient samples, no data) MISSING_DATA is filled for the given acceleration.
[out]	vel_sample	Velocity for sample. Expects a FSAMPLE structure to fill in the sample, the velocity is calculated for.

int eyelink_calculate_overallvelocity_and_acceleration2	(	int	slen,
		GAZE_MOTION *	gazeMotion,
		FSAMPLE2 *	vel_sample
	)

Calculates overall velocity and acceleration2 for left and right eyes separately.

Parameters

[in]	slen	Sample model to use for velocity calculation. Acceptable models are `FIVE_SAMPLE_MODEL`, `NINE_SAMPLE_MODEL`, `SEVENTEEN_SAMPLE_MODEL` and `EL1000_TRACKER_MODEL`.
[out]	gazeMotion	GAZE_MOTION structure that has x,y of gaze, head-in-space and eye-in-head velocity and acceleration
[out]	vel_sample	Velocity for sample. Expects a FSAMPLE2 structure to fill in the sample, the velocity is calculated for.

Remarks: GAZE_MOTION and FSAMPLE2 both contain extra data for the EyeLink 3 that defaults to 0 or MISSING for preceding camera models.

int eyelink_calculate_velocity	(	int	slen,
		float	vel[2],
		FSAMPLE *	vel_sample
	)

Calculates overall velocity for left and right eyes separately.

Parameters

[in]	slen	Sample model to use for velocity calculation. Acceptable models are `FIVE_SAMPLE_MODEL`, `NINE_SAMPLE_MODEL`, `SEVENTEEN_SAMPLE_MODEL` and `EL1000_TRACKER_MODEL`.
[out]	vel	A float array of 2 to fill in the calculated results. Upon return of this function, vel[0] will contain overall velocity for left eye and vel[1] will contain overall velocity for right eye. If velocity cannot be calculated for any reason(eg. insufficient samples, no data) MISSING_DATA is filled for the given velocity.
[out]	vel_sample	Velocity for sample. Expects a FSAMPLE structure to fill in the sample, the velocity is calculated for.

int eyelink_calculate_velocity_x_y	(	int	slen,
		float	xvel[2],
		float	yvel[2],
		FSAMPLE *	vel_sample
	)

Calculates left x velocity, left y velocity, right x velocity and right y velocity from queue of samples.

Parameters

[in]	slen	Sample model to use for velocity calculation. Acceptable models are `FIVE_SAMPLE_MODEL`, `NINE_SAMPLE_MODEL`, `SEVENTEEN_SAMPLE_MODEL` and `EL1000_TRACKER_MODEL`.
[out]	xvel	Left and right x velocity. Expects an array of 2 elements of floats. The array is filled with left and right velocity values. Upon return of this function xvel[0] contains the left x velocity data and xvel[1] contains right x velocity data. If velocity cannot be calculated for any reason(eg. insufficient samples, no data) MISSING_DATA is filled for the given velocity.
[out]	yvel	Left and right y velocity. Expects an array of 2 elements of floats. The array is filled with left and right velocity values. Upon return of this function yvel[0] contains the left y velocity data and xvel[1] contains right y velocity data. If velocity cannot be calculated for any reason(eg. insufficient samples, no data) MISSING_DATA is filled for the given velocity.
[out]	vel_sample	Velocity for sample. Expects a FSAMPLE structure to fill in the sample, the velocity is calculated for.

\b Example:

 #include <stdio.h>
 #include <core_expt.h>
 
 int main(int argc, char ** argv)
 {
     if(open_eyelink_connection(0)) // connect to tracker
     {
             return -1;
     }
 
     eyecmd_printf("link_sample_data  = LEFT,RIGHT,GAZE,GAZERES,AREA,STATUS"); // tell the tracker to stuff the sample with
     if(start_recording(0,0,1,0)) // start recording failed.
     {
             close_eyelink_connection();
             return -1;
     }
 
     if(!eyelink_wait_for_block_start(100, 1, 0)) // wait for block start
     {
             stop_recording();
             close_eyelink_connection();
             return -1;
     }
     else
     {
             UINT32 st = current_time();
             while(current_time()-st<10000) // record for 10 seconds
             {
                     FSAMPLE fs;
                     float xvel[2];
                     float yvel[2];
                     if(check_recording()!=0)
                     {
                             close_eyelink_connection();
                             return -4; // recording aborted.
                     }
                     eyelink_calculate_velocity_x_y(FIVE_SAMPLE_MODEL,xvel,yvel,&fs);
                     printf("%lu %f %f %f %f\n",fs.time,xvel[0],yvel[0], xvel[1], yvel[1]);
                     pump_delay(100); // we check the velocity every 100 ms.
             }
             stop_recording();
             close_eyelink_connection();
             return 0;
     }
 }

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation