Extract extended data from samples and events

Functions
INT32	eyelink_initialize_mapping (float left, float top, float right, float bottom)
INT32	eyelink_href_to_gaze (float *xp, float *yp, FSAMPLE *sample)
INT32	eyelink_gaze_to_href (float *xp, float *yp, FSAMPLE *sample)
float	eyelink_href_angle (float x1, float y1, float x2, float y2)
void	eyelink_href_resolution (float x, float y, float *xres, float *yres)

Detailed Description

Function Documentation

INT32 eyelink_gaze_to_href	(	float *	xp,
		float *	yp,
		FSAMPLE *	sample
	)

Apply gaze->href to point (xp, yp). This function requires HREFPT data in FSAMPLE. The function eyelink_initialize_mapping() should be called before calling this function.

Parameters

xp	X point to apply gaze->href.
yp	Y point to apply gaze->href.
sample	Sample.

Returns

0 if OK, -1 if there is a math error, -2 if the tracker does not support this operation.

float eyelink_href_angle	(	float	x1,
		float	y1,
		float	x2,
		float	y2
	)

Convenient function to calculate the href angle.

Parameters

x1	Point 1 x.
y1	Point 1 y.
x2	Point 2 x.
y2	Point 2 y.

void eyelink_href_resolution	(	float	x,
		float	y,
		float *	xres,
		float *	yres
	)

Convenient function to calculate the href resolution.

Parameters

x	X value of point.
y	Y value of point.
xres	Pointer to return the x resolution.
yres	Pointer to return the y resolution.

INT32 eyelink_href_to_gaze	(	float *	xp,
		float *	yp,
		FSAMPLE *	sample
	)

Apply href->gaze to point (xp, yp). This function requires HREFPT data in FSAMPLE. The function eyelink_initialize_mapping() should be called before calling this function.

Parameters

xp	X point to apply href->gaze.
yp	Y point to apply href->gaze.
sample	Sample.

Returns

0 if OK, -1 if there is a math error, -2 if the tracker does not support this operation.

INT32 eyelink_initialize_mapping	(	float	left,
		float	top,
		float	right,
		float	bottom
	)

Function to initialize the gaze to href and href to gaze mapping. This function should be called before calling eyelink_href_to_gaze() or eyelink_gaze_to_href().

Parameters

left	Left pixel value (normally 0).
top	Top pixel value (normally 0).
right	Right pixel value (width of the display).
bottom	Bottom pixel value (height of the display).

Returns

-1 if the tracker does not support the commands, href_point_eye set_href_point