Macros
#define	OHMD_APIENTRY

#define	OHMD_STR_SIZE 256

Typedefs
typedef struct ohmd_context	ohmd_context

typedef struct ohmd_device	ohmd_device

Enumerations
enum	ohmd_string_value { OHMD_VENDOR = 0, OHMD_PRODUCT = 1, OHMD_PATH = 2 }

enum	ohmd_float_value { OHMD_ROTATION_QUAT = 1, OHMD_LEFT_EYE_GL_MODELVIEW_MATRIX = 2, OHMD_RIGHT_EYE_GL_MODELVIEW_MATRIX = 3, OHMD_LEFT_EYE_GL_PROJECTION_MATRIX = 4, OHMD_RIGHT_EYE_GL_PROJECTION_MATRIX = 5, OHMD_POSITION_VECTOR = 6, OHMD_SCREEN_HORIZONTAL_SIZE = 7, OHMD_SCREEN_VERTICAL_SIZE = 8, OHMD_LENS_HORIZONTAL_SEPARATION = 9, OHMD_LENS_VERTICAL_POSITION = 10, OHMD_LEFT_EYE_FOV = 11, OHMD_LEFT_EYE_ASPECT_RATIO = 12, OHMD_RIGHT_EYE_FOV = 13, OHMD_RIGHT_EYE_ASPECT_RATIO = 14, OHMD_EYE_IPD = 15, OHMD_PROJECTION_ZFAR = 16, OHMD_PROJECTION_ZNEAR = 17, OHMD_DISTORTION_K = 18 }

enum	ohmd_int_value { OHMD_SCREEN_HORIZONTAL_RESOLUTION = 0, OHMD_SCREEN_VERTICAL_RESOLUTION = 1 }

Functions
OHMD_APIENTRY ohmd_context *	ohmd_ctx_create ()

OHMD_APIENTRY void	ohmd_ctx_destroy (ohmd_context *ctx)

OHMD_APIENTRY const char *	ohmd_ctx_get_error (ohmd_context *ctx)

OHMD_APIENTRY void	ohmd_ctx_update (ohmd_context *ctx)

OHMD_APIENTRY int	ohmd_ctx_probe (ohmd_context *ctx)

OHMD_APIENTRY const char *	ohmd_list_gets (ohmd_context *ctx, int index, ohmd_string_value type)

OHMD_APIENTRY ohmd_device *	ohmd_list_open_device (ohmd_context *ctx, int index)

OHMD_APIENTRY int	ohmd_device_getf (ohmd_device device, ohmd_float_value type, float out)

OHMD_APIENTRY int	ohmd_device_setf (ohmd_device device, ohmd_float_value type, float in)

OHMD_APIENTRY int	ohmd_device_geti (ohmd_device device, ohmd_int_value type, int out)

Detailed Description

Main header for OpenHMD public API.

Macro Definition Documentation

#define OHMD_STR_SIZE 256

Maximum length of a string, including termination, in OpenHMD.

Typedef Documentation

typedef struct ohmd_context ohmd_context

An opaque pointer to a context structure.

typedef struct ohmd_device ohmd_device

An opaque pointer to a structure representing a device, such as an HMD.

Enumeration Type Documentation

enum ohmd_float_value

A collection of float value information types, used for getting and setting information with ohmd_device_getf() and ohmd_device_setf().

Enumerator
OHMD_ROTATION_QUAT	float[4] (get): Absolute rotation of the device, in space, as a quaternion (x, y, z, w).
OHMD_LEFT_EYE_GL_MODELVIEW_MATRIX	float[16] (get): A "ready to use" OpenGL style 4x4 matrix with a modelview matrix for the left eye of the HMD.
OHMD_RIGHT_EYE_GL_MODELVIEW_MATRIX	float[16] (get): A "ready to use" OpenGL style 4x4 matrix with a modelview matrix for the right eye of the HMD.
OHMD_LEFT_EYE_GL_PROJECTION_MATRIX	float[16] (get): A "ready to use" OpenGL style 4x4 matrix with a projection matrix for the left eye of the HMD.
OHMD_RIGHT_EYE_GL_PROJECTION_MATRIX	float[16] (get): A "ready to use" OpenGL style 4x4 matrix with a projection matrix for the right eye of the HMD.
OHMD_POSITION_VECTOR	float[3] (get): A 3-D vector representing the absolute position of the device, in space.
OHMD_SCREEN_HORIZONTAL_SIZE	float[1] (get): Physical width of the device screen in metres.
OHMD_SCREEN_VERTICAL_SIZE	float[1] (get): Physical height of the device screen in metres.
OHMD_LENS_HORIZONTAL_SEPARATION	float[1] (get): Physical separation of the device lenses in metres.
OHMD_LENS_VERTICAL_POSITION	float[1] (get): Physical vertical position of the lenses in metres.
OHMD_LEFT_EYE_FOV	float[1] (get): Physical field of view for the left eye in degrees.
OHMD_LEFT_EYE_ASPECT_RATIO	float[1] (get): Physical display aspect ratio for the left eye screen.
OHMD_RIGHT_EYE_FOV	float[1] (get): Physical field of view for the left right in degrees.
OHMD_RIGHT_EYE_ASPECT_RATIO	float[1] (get): Physical display aspect ratio for the right eye screen.
OHMD_EYE_IPD	float[1] (get, set): Physical interpupillary distance of the user in metres.
OHMD_PROJECTION_ZFAR	float[1] (get, set): Z-far value for the projection matrix calculations (i.e. drawing distance).
OHMD_PROJECTION_ZNEAR	float[1] (get, set): Z-near value for the projection matrix calculations (i.e. close clipping distance).
OHMD_DISTORTION_K	float[6] (get): Device specific distortion value.

enum ohmd_int_value

A collection of int value information types used for getting information with ohmd_device_geti().

Enumerator
OHMD_SCREEN_HORIZONTAL_RESOLUTION	int[1] (get): Physical horizontal resolution of the device screen.
OHMD_SCREEN_VERTICAL_RESOLUTION	int[1] (get): Physical vertical resolution of the device screen.

enum ohmd_string_value

A collection of string value information types, used for getting information with ohmd_list_gets().

Function Documentation

OHMD_APIENTRY ohmd_context* ohmd_ctx_create ( )

Create an OpenHMD context.

Returns: a pointer to an allocated ohmd_context on success or NULL if it fails.

OHMD_APIENTRY void ohmd_ctx_destroy ( ohmd_context * ctx )

Destroy an OpenHMD context.

ohmd_ctx_destroy de-initializes and de-allocates an OpenHMD context allocated with ohmd_ctx_create.

Parameters

ctx	The context to destroy.

OHMD_APIENTRY const char* ohmd_ctx_get_error ( ohmd_context * ctx )

Get the last error as a human readable string.

If a function taking a context as an argument (ohmd_context "methods") returns non-successfully, a human readable error message describing what went wrong can be retrieved with this function.

Parameters

ctx	The context to retrieve the error message from.

Returns: a pointer to the error message.

OHMD_APIENTRY int ohmd_ctx_probe ( ohmd_context * ctx )

Probe for devices.

Probes for and enumerates supported devices attached to the system.

Parameters

ctx	A context with no currently open devices.

Returns: the number of devices found on the system.

OHMD_APIENTRY void ohmd_ctx_update ( ohmd_context * ctx )

Update a context.

Performs tasks like pumping events from the device. The exact details are up to the driver but try to call it quite frequently. Once per frame in a "game loop" should be sufficient. If OpenHMD is handled in a background thread, calling ohmd_ctx_update and then sleeping for 10-20 ms is recommended.

Parameters

ctx	The context that needs updating.

OHMD_APIENTRY int ohmd_device_getf	(	ohmd_device *	device,
		ohmd_float_value	type,
		float *	out
	)

Get a floating point value from a device.

Parameters

	device	An open device to retrieve the value from.
	type	What type of value to retrieve, see ohmd_float_value section for more information.
[out]	out	A pointer to a float, or float array where the retrieved value should be written.

Returns: 0 on success, <0 on failure.

OHMD_APIENTRY int ohmd_device_geti	(	ohmd_device *	device,
		ohmd_int_value	type,
		int *	out
	)

Get an integer value from a device.

Parameters

	device	An open device to retrieve the value from.
	type	What type of value to retrieve, ohmd_int_value section for more information.
[out]	out	A pointer to an integer, or integer array where the retrieved value should be written.

Returns: 0 on success, <0 on failure.

OHMD_APIENTRY int ohmd_device_setf	(	ohmd_device *	device,
		ohmd_float_value	type,
		float *	in
	)

Set a floating point value for a device.

Parameters

device	An open device to set the value in.
type	What type of value to set, see ohmd_float_value section for more information.
in	A pointer to a float, or float array where the new value is stored.

Returns: 0 on success, <0 on failure.

OHMD_APIENTRY const char* ohmd_list_gets	(	ohmd_context *	ctx,
		int	index,
		ohmd_string_value	type
	)

Get device description from enumeration list index.

Gets a human readable device description string from a zero indexed enumeration index between 0 and (max - 1), where max is the number ohmd_ctx_probe returned (i.e. if ohmd_ctx_probe returns 3, valid indices are 0, 1 and 2). The function can return three types of data. The vendor name, the product name and a driver specific path where the device is attached.

ohmd_ctx_probe must be called before calling ohmd_list_gets.

Parameters

ctx	A (probed) context.
index	An index, between 0 and the value returned from ohmd_ctx_probe.
type	The type of data to fetch. One of OHMD_VENDOR, OHMD_PRODUCT and OHMD_PATH.

Returns: a string with a human readable device name.

OHMD_APIENTRY ohmd_device* ohmd_list_open_device	(	ohmd_context *	ctx,
		int	index
	)

Open a device.

Opens a device from a zero indexed enumeration index between 0 and (max - 1) where max is the number ohmd_ctx_probe returned (i.e. if ohmd_ctx_probe returns 3, valid indices are 0, 1 and 2).

ohmd_ctx_probe must be called before calling ohmd_list_open_device.

Parameters

ctx	A (probed) context.
index	An index, between 0 and the value returned from ohmd_ctx_probe.

Returns: a pointer to an ohmd_device, which represents a hardware device, such as an HMD.

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation