xrt_device.h

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// Copyright 2019-2024, Collabora, Ltd.
// Copyright 2024-2026, NVIDIA CORPORATION.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Header defining an xrt display or controller device.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @author Moshi Turner <moshiturner@protonmail.com>
 * @author Korcan Hussein <korcan.hussein@collabora.com>
 * @ingroup xrt_iface
 */
 
#pragma once
 
#include "xrt/xrt_defines.h"
#include "xrt/xrt_plane_detector.h"
#include "xrt/xrt_visibility_mask.h"
#include "xrt/xrt_limits.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
struct xrt_tracking;
 
#define XRT_DEVICE_NAME_LEN 256
 
 
/*!
 * A unique identifier for an @ref xrt_device instance.
 *
 * Each device is assigned a 64-bit ID when it is created in the Monado service
 * process, or in the application process for in-process setups. For
 * out-of-process clients the ID is synchronized over the IPC layer, so every
 * client connected to the same service refers to a given device by the same
 * value.
 *
 * The ID is intended for hash maps, caches, and similar lookups. Unlike a
 * memory pointer it is never reused after the device is destroyed.
 *
 * A value of zero is invalid and means the device ID has not been assigned,
 * matching the zero-initialized state of the struct.
 *
 * @ingroup xrt_iface
 */
struct xrt_device_id
{
        uint64_t val;
};
 
/*!
 * A per-lens/display view information.
 *
 * @ingroup xrt_iface
 */
struct xrt_view
{
        /*!
         * @brief Viewport position on the screen.
         *
         * In absolute screen coordinates on an unrotated display, like the
         * HMD presents it to the OS.
         *
         * This field is only used by @ref comp to setup the device rendering.
         *
         * If the view is being rotated by xrt_view.rot 90° right in the
         * distortion shader then `display.w_pixels == viewport.h_pixels` and
         * `display.h_pixels == viewport.w_pixels`.
         */
        struct
        {
                uint32_t x_pixels;
                uint32_t y_pixels;
                uint32_t w_pixels;
                uint32_t h_pixels;
        } viewport;
 
        /*!
         * @brief Physical properties of this display (or the part of a display
         * that covers this view).
         *
         * Not in absolute screen coordinates but like the clients see them i.e.
         * after rotation is applied by xrt_view::rot.
         * This field is only used for the clients' swapchain setup.
         *
         * The xrt_view::display::w_pixels and xrt_view::display::h_pixels
         * become the recommended image size for this view, after being scaled
         * by the debug environment variable `XRT_COMPOSITOR_SCALE_PERCENTAGE`.
         */
        struct
        {
                uint32_t w_pixels;
                uint32_t h_pixels;
        } display;
 
        /*!
         * @brief Rotation 2d matrix used to rotate the position of the output
         * of the distortion shaders onto the screen.
         *
         * If the distortion shader is based on a mesh, then this matrix rotates
         * the vertex positions.
         */
        struct xrt_matrix_2x2 rot;
};
 
/*!
 * @brief Compositor information for a device.
 */
struct xrt_device_compositor_info
{
        //! The direction scanout on the display occurs.
        enum xrt_scanout_direction scanout_direction;
        /*!
         * The amount of time it takes to scanout the display in nanoseconds, from the start of the scanout, to the end
         * of the scanout.
         *
         * @note alignas for 32 bit client support, see @ref ipc-design
         */
        XRT_ALIGNAS(8) int64_t scanout_time_ns;
};
 
/*!
 * @brief Compositor mode information for a device.
 */
struct xrt_device_compositor_mode
{
        //! The amount of nanoseconds between frames.
        int64_t frame_interval_ns;
};
 
/*!
 * All of the device components that deals with interfacing to a users head.
 *
 * HMD is probably a bad name for the future but for now will have to do.
 *
 * @ingroup xrt_iface
 */
struct xrt_hmd_parts
{
        /*!
         * @brief The hmd screen as an unrotated display, like the HMD presents
         * it to the OS.
         *
         * This field is used by @ref comp to setup the extended mode window.
         */
        struct
        {
                int w_pixels;
                int h_pixels;
                //! Nominal frame interval
                uint64_t nominal_frame_interval_ns;
        } screens[1];
 
        /*!
         * Display information.
         *
         * For now hardcoded display to two.
         */
        struct xrt_view views[XRT_MAX_VIEWS];
 
        size_t view_count;
        /*!
         * Array of supported blend modes.
         */
        enum xrt_blend_mode blend_modes[XRT_MAX_DEVICE_BLEND_MODES];
        size_t blend_mode_count;
 
        /*!
         * Distortion information.
         */
        struct
        {
                //! Supported distortion models, a bitfield.
                enum xrt_distortion_model models;
                //! Preferred disortion model, single value.
                enum xrt_distortion_model preferred;
 
                struct
                {
                        //! Data.
                        float *vertices;
                        //! Number of vertices.
                        uint32_t vertex_count;
                        //! Stride of vertices
                        uint32_t stride;
                        //! 1 or 3 for (chromatic aberration).
                        uint32_t uv_channels_count;
 
                        //! Indices, for triangle strip.
                        int *indices;
                        //! Number of indices for the triangle strips (one per view).
                        uint32_t index_counts[XRT_MAX_VIEWS];
                        //! Offsets for the indices (one offset per view).
                        uint32_t index_offsets[XRT_MAX_VIEWS];
                        //! Total number of elements in mesh::indices array.
                        uint32_t index_count_total;
                } mesh;
 
                //! distortion is subject to the field of view
                struct xrt_fov fov[XRT_MAX_VIEWS];
        } distortion;
};
 
/*!
 * A single named input, that sits on a @ref xrt_device.
 *
 * @ingroup xrt_iface
 */
struct xrt_input
{
        //! Is this input active.
        bool active;
 
        //! alignas for 32 bit client support, see @ref ipc-design
        XRT_ALIGNAS(8) int64_t timestamp;
 
        enum xrt_input_name name;
 
        union xrt_input_value value;
};
 
/*!
 * A single named output, that sits on a @ref xrt_device.
 *
 * @ingroup xrt_iface
 */
struct xrt_output
{
        enum xrt_output_name name;
};
 
 
/*!
 * A binding pair, going @p from a binding point to a @p device input.
 *
 * @ingroup xrt_iface
 */
struct xrt_binding_input_pair
{
        enum xrt_input_name from;   //!< From which name.
        enum xrt_input_name device; //!< To input on the device.
};
 
/*!
 * A binding pair, going @p from a binding point to a @p device output.
 *
 * @ingroup xrt_iface
 */
struct xrt_binding_output_pair
{
        enum xrt_output_name from;   //!< From which name.
        enum xrt_output_name device; //!< To output on the device.
};
 
/*!
 * A binding profile, has lists of binding pairs to goes from device in @p name
 * to the device it hangs off on.
 *
 * @ingroup xrt_iface
 */
struct xrt_binding_profile
{
        //! Device this binding emulates.
        enum xrt_device_name name;
 
        struct xrt_binding_input_pair *inputs;
        size_t input_count;
        struct xrt_binding_output_pair *outputs;
        size_t output_count;
};
 
/*!
 * Higher level features for devices.
 */
enum xrt_device_feature_type
{
        XRT_DEVICE_FEATURE_HAND_TRACKING_LEFT = 0,
        XRT_DEVICE_FEATURE_HAND_TRACKING_RIGHT,
        XRT_DEVICE_FEATURE_EYE_TRACKING,
        XRT_DEVICE_FEATURE_FACE_TRACKING,
        XRT_DEVICE_FEATURE_MAX_ENUM,
};
 
/*!
 * Output limits of a particular device
 */
struct xrt_output_limits
{
        //! The sample rate of the device's haptic PCM support, 0 if haptic PCM is not supported.
        float haptic_pcm_sample_rate;
};
 
/*!
 * Static data of supported features of the @ref xrt_device this struct sits on.
 *
 * This struct needs to always be a piece of data as it sits inside of the
 * shared memory area in the IPC layer, so no pointers please.
 *
 * @ingroup xrt_iface
 */
struct xrt_device_supported
{
        bool orientation_tracking;
        bool position_tracking;
        bool hand_tracking;
        bool eye_gaze;
        bool presence;
        bool force_feedback;
        bool ref_space_usage;
        bool form_factor_check;
        bool stage;
        bool face_tracking;
        bool face_tracking_calibration_state;
        bool body_tracking;
        bool body_tracking_calibration;
        bool body_tracking_fidelity;
        bool battery_status;
        bool brightness_control;
        bool compositor_info;
 
        bool planes;
        enum xrt_plane_detection_capability_flags_ext plane_capability_flags;
 
        /*!
         * The device itself only has 2 views but is aware of quad views, has
         * better knowledge of which fovs to use for quad views to stereo views
         * emulation. So it supports retrieving quad views from get_views.
         */
        bool get_views_quad;
};
 
/*!
 * @interface xrt_device
 *
 * A single HMD or input device.
 *
 * @ingroup xrt_iface
 */
struct xrt_device
{
        //! Instance identifier, see @ref xrt_device_id.
        struct xrt_device_id id;
 
        //! Enum identifier of the device.
        enum xrt_device_name name;
        enum xrt_device_type device_type;
 
        //! A string describing the device.
        char str[XRT_DEVICE_NAME_LEN];
 
        //! A unique identifier. Persistent across configurations, if possible.
        char serial[XRT_DEVICE_NAME_LEN];
 
        //! Null if this device does not interface with the users head.
        struct xrt_hmd_parts *hmd;
 
        //! Always set, pointing to the tracking system for this device.
        struct xrt_tracking_origin *tracking_origin;
 
        //! Number of bindings in xrt_device::binding_profiles
        size_t binding_profile_count;
        // Array of alternative binding profiles.
        struct xrt_binding_profile *binding_profiles;
 
        //! Number of inputs.
        size_t input_count;
        //! Array of input structs.
        struct xrt_input *inputs;
 
        //! Number of outputs.
        size_t output_count;
        //! Array of output structs.
        struct xrt_output *outputs;
 
        //! What features/functions/things does this device supports?
        struct xrt_device_supported supported;
 
 
        /*
         *
         * Functions.
         *
         */
 
        /*!
         * Update any attached inputs.
         *
         * @param[in] xdev        The device.
         */
        xrt_result_t (*update_inputs)(struct xrt_device *xdev);
 
        /*!
         * @brief Get relationship of a tracked device to the tracking origin
         * space as the base space.
         *
         * It is the responsibility of the device driver to do any prediction,
         * there are helper functions available for this.
         *
         * The timestamps are system monotonic timestamps, such as returned by
         * os_monotonic_get_ns().
         *
         * @param[in] xdev           The device.
         * @param[in] name           Some devices may have multiple poses on
         *                           them, select the one using this field. For
         *                           HMDs use @p XRT_INPUT_GENERIC_HEAD_POSE.
         *                           For Unbounded Reference Space you can use
         *                           @p XRT_INPUT_GENERIC_UNBOUNDED_SPACE_POSE
         *                           to get the origin of that space.
         * @param[in] at_timestamp_ns If the device can predict or has a history
         *                            of positions, this is when the caller
         *                            wants the pose to be from.
         * @param[out] out_relation The relation read from the device.
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_tracked_pose)(struct xrt_device *xdev,
                                         enum xrt_input_name name,
                                         int64_t at_timestamp_ns,
                                         struct xrt_space_relation *out_relation);
 
        /*!
         * @brief Get relationship of hand joints to the tracking origin space as
         * the base space.
         *
         * It is the responsibility of the device driver to either do prediction
         * or return joints from a previous time and write that time out to
         * @p out_timestamp_ns.
         *
         * The timestamps are system monotonic timestamps, such as returned by
         * os_monotonic_get_ns().
         *
         * @param[in] xdev                 The device.
         * @param[in] name                 Some devices may have multiple poses on
         *                                 them, select the one using this field. For
         *                                 hand tracking use @p XRT_INPUT_GENERIC_HAND_TRACKING_DEFAULT_SET.
         * @param[in] desired_timestamp_ns If the device can predict or has a history
         *                                 of positions, this is when the caller
         *                                 wants the pose to be from.
         * @param[out] out_value           The hand joint data read from the device.
         * @param[out] out_timestamp_ns    The timestamp of the data being returned.
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_hand_tracking)(struct xrt_device *xdev,
                                          enum xrt_input_name name,
                                          int64_t desired_timestamp_ns,
                                          struct xrt_hand_joint_set *out_value,
                                          int64_t *out_timestamp_ns);
 
        /*!
         * @brief Get the requested blend shape properties & weights for a face tracker
         *
         * @param[in] xdev                    The device.
         * @param[in] facial_expression_type  The facial expression data type (XR_FB_face_tracking,
         * XR_HTC_facial_tracking, etc).
         * @param[in] at_timestamp_ns         Timestamp to be optionally used for prediction/history. For OXR extensions
         * that do not pass a timestamp, the current timestamp is used.
         * @param[in] out_value               Set of requested expression weights & blend shape properties.
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_face_tracking)(struct xrt_device *xdev,
                                          enum xrt_input_name facial_expression_type,
                                          int64_t at_timestamp_ns,
                                          struct xrt_facial_expression_set *out_value);
 
        /*!
         * @brief Gets the face tracking calibration state
         *
         * @param[in] xdev                    The device.
         * @param[in] out_face_is_calibrated  Is face tracking calibrated?
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_face_calibration_state_android)(struct xrt_device *xdev, bool *out_face_is_calibrated);
 
        /*!
         * @brief Get the body skeleton in T-pose, used to query the skeleton hierarchy, scale, proportions etc
         *
         * @param[in] xdev                    The device.
         * @param[in] body_tracking_type      The body joint set type (XR_FB_body_tracking,
         * XR_META_body_tracking_full_body, etc).
         * @param[in] out_value               The body skeleton hierarchy/properties.
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_body_skeleton)(struct xrt_device *xdev,
                                          enum xrt_input_name body_tracking_type,
                                          struct xrt_body_skeleton *out_value);
 
        /*!
         * @brief Get the joint locations for a body tracker
         *
         * @param[in] xdev                    The device.
         * @param[in] body_tracking_type      The body joint set type (XR_FB_body_tracking,
         * XR_META_body_tracking_full_body, etc).
         * @param[in] desired_timestamp_ns    If the device can predict or has a history
         *                                    of locations, this is when the caller
         * @param[in] out_value               Set of body joint locations & properties.
         *
         * @see xrt_input_name
         */
        xrt_result_t (*get_body_joints)(struct xrt_device *xdev,
                                        enum xrt_input_name body_tracking_type,
                                        int64_t desired_timestamp_ns,
                                        struct xrt_body_joint_set *out_value);
 
        /*!
         * @brief XR_META_body_tracking_calibration - body tracking extension to reset the body tracking calibration
         *
         * @param[in] xdev              The body tracking device.
         */
        xrt_result_t (*reset_body_tracking_calibration_meta)(struct xrt_device *xdev);
 
        /*!
         * @brief XR_META_body_tracking_calibration - body tracking extension to suggest a body tracking calibration
         * override
         *
         * @param[in] xdev              The body tracking device.
         * @param[in] new_body_height   The suggested new body height to override.
         */
        xrt_result_t (*set_body_tracking_calibration_override_meta)(struct xrt_device *xdev, float new_body_height);
 
        /*!
         * @brief XR_META_body_tracking_fidelity - body tracking extension for request changing the tracking fidelity
         *
         * @param[in] xdev              The body tracking device.
         * @param[in] new_fidelity      The new tracking fidelity mode.
         *
         * @see xrt_body_tracking_fidelity_meta
         */
        xrt_result_t (*set_body_tracking_fidelity_meta)(struct xrt_device *xdev,
                                                        enum xrt_body_tracking_fidelity_meta new_fidelity);
 
        /*!
         * Set a output value.
         *
         * @param[in] xdev           The device.
         * @param[in] name           The output component name to set.
         * @param[in] value          The value to set the output to.
         * @see xrt_output_name
         */
        xrt_result_t (*set_output)(struct xrt_device *xdev,
                                   enum xrt_output_name name,
                                   const struct xrt_output_value *value);
 
        /*!
         * Gets limits of this devices outputs.
         *
         * @param[in] xdev           The device.
         * @param[out] limits        The returned limits.
         */
        xrt_result_t (*get_output_limits)(struct xrt_device *xdev, struct xrt_output_limits *limits);
 
        /*!
         * Begin a plane detection request
         *
         * @param[in] xdev               The device.
         * @param[in] begin_info         The query specifying what type of planes are requested.
         * @param[in] plane_detection_id  The id for a previous plane detection request to be replaced or 0.
         * @param[out] out_plane_detection_id  The id of the new plane detection request generated by the xdev.
         * @return generally XRT_SUCCESS, except for internal runtime failures.
         */
        xrt_result_t (*begin_plane_detection_ext)(struct xrt_device *xdev,
                                                  const struct xrt_plane_detector_begin_info_ext *begin_info,
                                                  uint64_t plane_detection_id,
                                                  uint64_t *out_plane_detection_id);
 
        /*!
         * Destroy internal resources associated with plane_detector_id.
         *
         * @param[in] xdev               The device.
         * @param[in] plane_detection_id  An id generated by the xdev.
         * @return generally XRT_SUCCESS, except for internal runtime failures.
         */
        xrt_result_t (*destroy_plane_detection_ext)(struct xrt_device *xdev, uint64_t plane_detection_id);
 
        /*!
         * Get the state of a plane detection request.
         *
         * @param[in] xdev               The device.
         * @param[in] plane_detector_id  An id generated by the xdev.
         * @param[out] out_state         The state of the plane detection.
         * @return generally XRT_SUCCESS, except for internal runtime failures.
         */
        xrt_result_t (*get_plane_detection_state_ext)(struct xrt_device *xdev,
                                                      uint64_t plane_detection_id,
                                                      enum xrt_plane_detector_state_ext *out_state);
 
        /*!
         * Get results of a plane detection request.
         *
         * @param[in] xdev               The device.
         * @param[in] plane_detector_id  An id generated by the xdev.
         * @param[out] detections        The detected planes, if any.
         * @return generally XRT_SUCCESS, except for internal runtime failures.
         */
        xrt_result_t (*get_plane_detections_ext)(struct xrt_device *xdev,
                                                 uint64_t plane_detection_id,
                                                 struct xrt_plane_detections_ext *out_detections);
 
        /*!
         * @brief Get the per-view pose in relation to the view space.
         *
         * On most devices with coplanar displays and no built-in eye tracking
         * or IPD sensing, this just calls a helper to process the provided
         * eye relation, but this may also handle canted displays as well as
         * eye tracking.
         *
         * Incorporates a call to xrt_device::get_tracked_pose or a wrapper for it
         *
         * @param[in] xdev         The device.
         * @param[in] default_eye_relation
         *                         The interpupillary relation as a 3D position.
         *                         Most simple stereo devices would just want to
         *                         set `out_pose->position.[x|y|z] = ipd.[x|y|z]
         *                         / 2.0f` and adjust for left vs right view.
         *                         Not to be confused with IPD that is absolute
         *                         distance, this is a full 3D translation
         *                         If a device has a more accurate/dynamic way of
         *                         knowing the eye relation, it may ignore this
         *                         input.
         * @param[in] at_timestamp_ns This is when the caller wants the poses and FOVs to be from.
         * @param[in] view_count   Number of views.
         * @param[in] view_type    Type of view configuration (mono or stereo).
         * @param[out] out_head_relation
         *                         The head pose in the device tracking space.
         *                         Combine with @p out_poses to get the views in
         *                         device tracking space.
         * @param[out] out_fovs    An array (of size @p view_count ) to populate
         *                         with the device-suggested fields of view.
         * @param[out] out_poses   An array (of size @p view_count ) to populate
         *                         with view output poses in head space. When
         *                         implementing, be sure to also set orientation:
         *                         most likely identity orientation unless you
         *                         have canted screens.
         *                         (Caution: Even if you have eye tracking, you
         *                         won't use eye orientation here!)
         */
        xrt_result_t (*get_view_poses)(struct xrt_device *xdev,
                                       const struct xrt_vec3 *default_eye_relation,
                                       int64_t at_timestamp_ns,
                                       enum xrt_view_type view_type,
                                       uint32_t view_count,
                                       struct xrt_space_relation *out_head_relation,
                                       struct xrt_fov *out_fovs,
                                       struct xrt_pose *out_poses);
 
        /**
         * Compute the distortion at a single point.
         *
         * The input is @p u @p v in screen/output space (that is, predistorted), you are to compute and return the u,v
         * coordinates to sample the render texture. The compositor will step through a range of u,v parameters to build
         * the lookup (vertex attribute or distortion texture) used to pre-distort the image as required by the device's
         * optics.
         *
         * @param xdev            the device
         * @param view            the view index
         * @param u               horizontal texture coordinate
         * @param v               vertical texture coordinate
         * @param[out] out_result corresponding u,v pairs for all three color channels.
         */
        xrt_result_t (*compute_distortion)(
            struct xrt_device *xdev, uint32_t view, float u, float v, struct xrt_uv_triplet *out_result);
 
        /*!
         * Get the visibility mask for this device.
         *
         * @param[in] xdev       The device.
         * @param[in] type       The type of visibility mask.
         * @param[in] view_index The index of the view to get the mask for.
         * @param[out] out_mask  Output mask, caller must free.
         */
        xrt_result_t (*get_visibility_mask)(struct xrt_device *xdev,
                                            enum xrt_visibility_mask_type type,
                                            uint32_t view_index,
                                            struct xrt_visibility_mask **out_mask);
 
        /*!
         * Called by the @ref xrt_space_overseer when a reference space that is
         * implemented by this device is first used, or when the last usage of
         * the reference space stops.
         *
         * What is provided is both the @ref xrt_reference_space_type that
         * triggered the usage change and the @ref xrt_input_name (if any) that
         * is used to drive the space.
         *
         * @see xrt_space_overseer_ref_space_inc
         * @see xrt_space_overseer_ref_space_dec
         * @see xrt_input_name
         * @see xrt_reference_space_type
         */
        xrt_result_t (*ref_space_usage)(struct xrt_device *xdev,
                                        enum xrt_reference_space_type type,
                                        enum xrt_input_name name,
                                        bool used);
 
        /*!
         * @brief Check if given form factor is available or not.
         *
         * This should only be used in HMD device, if the device driver supports form factor check.
         *
         * @param[in] xdev The device.
         * @param[in] form_factor Form factor to check.
         * @param[out] out_available true if given form factor is available; otherwise false.
         */
        xrt_result_t (*is_form_factor_available)(struct xrt_device *xdev,
                                                 enum xrt_form_factor form_factor,
                                                 bool *out_available);
 
        /*!
         * @brief Get battery status information.
         *
         * @param[in] xdev          The device.
         * @param[out] out_present  Whether battery status information exist for this device.
         * @param[out] out_charging Whether the device's battery is being charged.
         * @param[out] out_charge   Battery charge as a value between 0 and 1.
         */
        xrt_result_t (*get_battery_status)(struct xrt_device *xdev,
                                           bool *out_present,
                                           bool *out_charging,
                                           float *out_charge);
 
        /*!
         * @brief Get the current display brightness.
         *
         * @param[in] xdev             The device.
         * @param[out] out_brightness  Current display brightness. Usually between 0 and 1. Some devices may
         *                             exceed 1 if the supported range exceeds 100%
         */
        xrt_result_t (*get_brightness)(struct xrt_device *xdev, float *out_brightness);
 
        /*!
         * @brief Set the display brightness.
         *
         * @param[in] xdev            The device.
         * @param[in] brightness      Desired display brightness. Usually between 0 and 1. Some devices may
         *                            allow exceeding 1 if the supported range exceeds 100%, but it will be clamped to
         *                            the supported range.
         * @param[in] relative        Whether to add \a brightness to the current brightness, instead of overwriting
         *                            the current brightness.
         */
        xrt_result_t (*set_brightness)(struct xrt_device *xdev, float brightness, bool relative);
 
        /*!
         * @brief Gets the compositor info for a device for the given mode.
         *
         * This function should never block, and never wait on congested locks.
         *
         * @param[in] xdev            The device.
         * @param[in] mode            The mode to query with.
         * @param[out] out_info       Populated with the output data.
         */
        xrt_result_t (*get_compositor_info)(struct xrt_device *xdev,
                                            const struct xrt_device_compositor_mode *mode,
                                            struct xrt_device_compositor_info *out_info);
 
        /*!
         * Enable the feature for this device.
         *
         * @param[in] xdev        The device.
         * @param[in] type        The type of device feature.
         */
        xrt_result_t (*begin_feature)(struct xrt_device *xdev, enum xrt_device_feature_type type);
 
        /*!
         * Disable the feature for this device.
         *
         * @param[in] xdev        The device.
         * @param[in] type        The type of device feature.
         */
        xrt_result_t (*end_feature)(struct xrt_device *xdev, enum xrt_device_feature_type type);
 
        /*!
         * Destroy device.
         */
        void (*destroy)(struct xrt_device *xdev);
 
        // Add new functions above destroy.
};
 
/*!
 * Helper function for @ref xrt_device::update_inputs.
 *
 * @copydoc xrt_device::update_inputs
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_update_inputs(struct xrt_device *xdev)
{
        return xdev->update_inputs(xdev);
}
 
/*!
 * Helper function for @ref xrt_device::get_tracked_pose.
 *
 * @copydoc xrt_device::get_tracked_pose
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_tracked_pose(struct xrt_device *xdev,
                            enum xrt_input_name name,
                            int64_t at_timestamp_ns,
                            struct xrt_space_relation *out_relation)
{
        return xdev->get_tracked_pose(xdev, name, at_timestamp_ns, out_relation);
}
 
/*!
 * Helper function for @ref xrt_device::get_hand_tracking.
 *
 * @copydoc xrt_device::get_hand_tracking
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_hand_tracking(struct xrt_device *xdev,
                             enum xrt_input_name name,
                             int64_t desired_timestamp_ns,
                             struct xrt_hand_joint_set *out_value,
                             int64_t *out_timestamp_ns)
{
        return xdev->get_hand_tracking(xdev, name, desired_timestamp_ns, out_value, out_timestamp_ns);
}
 
/*!
 * Helper function for @ref xrt_device::get_face_tracking.
 *
 * @copydoc xrt_device::get_face_tracking
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_face_tracking(struct xrt_device *xdev,
                             enum xrt_input_name facial_expression_type,
                             int64_t at_timestamp_ns,
                             struct xrt_facial_expression_set *out_value)
{
        return xdev->get_face_tracking(xdev, facial_expression_type, at_timestamp_ns, out_value);
}
 
/*!
 * Helper function for @ref xrt_device::get_face_calibration_state_android.
 *
 * @copydoc xrt_device::get_face_calibration_state_android
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_face_calibration_state_android(struct xrt_device *xdev, bool *out_face_is_calibrated)
{
        return xdev->get_face_calibration_state_android(xdev, out_face_is_calibrated);
}
 
/*!
 * Helper function for @ref xrt_device::get_body_skeleton.
 *
 * @copydoc xrt_device::get_body_skeleton
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_body_skeleton(struct xrt_device *xdev,
                             enum xrt_input_name body_tracking_type,
                             struct xrt_body_skeleton *out_value)
{
        return xdev->get_body_skeleton(xdev, body_tracking_type, out_value);
}
 
/*!
 * Helper function for @ref xrt_device::get_body_joints.
 *
 * @copydoc xrt_device::get_body_joints
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_body_joints(struct xrt_device *xdev,
                           enum xrt_input_name body_tracking_type,
                           int64_t desired_timestamp_ns,
                           struct xrt_body_joint_set *out_value)
{
        return xdev->get_body_joints(xdev, body_tracking_type, desired_timestamp_ns, out_value);
}
 
/*!
 * Helper function for @ref xrt_device::reset_body_tracking_calibration_meta.
 *
 * @copydoc xrt_device::reset_body_tracking_calibration_meta
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_reset_body_tracking_calibration_meta(struct xrt_device *xdev)
{
        if (xdev->reset_body_tracking_calibration_meta == NULL) {
                return XRT_ERROR_NOT_IMPLEMENTED;
        }
        return xdev->reset_body_tracking_calibration_meta(xdev);
}
 
/*!
 * Helper function for @ref xrt_device::set_body_tracking_calibration_override_meta.
 *
 * @copydoc xrt_device::set_body_tracking_calibration_override_meta
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_set_body_tracking_calibration_override_meta(struct xrt_device *xdev, float new_body_height)
{
        if (xdev->set_body_tracking_calibration_override_meta == NULL) {
                return XRT_ERROR_NOT_IMPLEMENTED;
        }
        return xdev->set_body_tracking_calibration_override_meta(xdev, new_body_height);
}
 
/*!
 * Helper function for @ref xrt_device::set_body_tracking_fidelity_meta.
 *
 * @copydoc xrt_device::set_body_tracking_fidelity_meta
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_set_body_tracking_fidelity_meta(struct xrt_device *xdev, enum xrt_body_tracking_fidelity_meta new_fidelity)
{
        if (xdev->set_body_tracking_fidelity_meta == NULL) {
                return XRT_ERROR_NOT_IMPLEMENTED;
        }
        return xdev->set_body_tracking_fidelity_meta(xdev, new_fidelity);
}
 
/*!
 * Helper function for @ref xrt_device::set_output.
 *
 * @copydoc xrt_device::set_output
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_set_output(struct xrt_device *xdev, enum xrt_output_name name, const struct xrt_output_value *value)
{
        xdev->set_output(xdev, name, value);
        return XRT_SUCCESS;
}
 
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_output_limits(struct xrt_device *xdev, struct xrt_output_limits *limits)
{
        if (xdev->get_output_limits) {
                return xdev->get_output_limits(xdev, limits);
        } else {
                return XRT_ERROR_NOT_IMPLEMENTED;
        }
}
 
/*!
 * Helper function for @ref xrt_device::begin_plane_detection_ext.
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_begin_plane_detection_ext(struct xrt_device *xdev,
                                     const struct xrt_plane_detector_begin_info_ext *begin_info,
                                     uint64_t plane_detection_id,
                                     uint64_t *out_plane_detection_id)
{
        return xdev->begin_plane_detection_ext(xdev, begin_info, plane_detection_id, out_plane_detection_id);
}
 
/*!
 * Helper function for @ref xrt_device::destroy_plane_detection_ext.
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_destroy_plane_detection_ext(struct xrt_device *xdev, uint64_t plane_detection_id)
{
        return xdev->destroy_plane_detection_ext(xdev, plane_detection_id);
}
 
/*!
 * Helper function for @ref xrt_device::get_plane_detections_ext.
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_plane_detection_state_ext(struct xrt_device *xdev,
                                         uint64_t plane_detection_id,
                                         enum xrt_plane_detector_state_ext *out_state)
{
        return xdev->get_plane_detection_state_ext(xdev, plane_detection_id, out_state);
}
 
/*!
 * Helper function for @ref xrt_device::get_plane_detections_ext.
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_plane_detections_ext(struct xrt_device *xdev,
                                    uint64_t plane_detection_id,
                                    struct xrt_plane_detections_ext *out_detections)
{
        return xdev->get_plane_detections_ext(xdev, plane_detection_id, out_detections);
}
 
/*!
 * Helper function for @ref xrt_device::get_view_poses.
 *
 * @copydoc xrt_device::get_view_poses
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_view_poses(struct xrt_device *xdev,
                          const struct xrt_vec3 *default_eye_relation,
                          int64_t at_timestamp_ns,
                          enum xrt_view_type view_type,
                          uint32_t view_count,
                          struct xrt_space_relation *out_head_relation,
                          struct xrt_fov *out_fovs,
                          struct xrt_pose *out_poses)
{
        return xdev->get_view_poses( //
            xdev,                    //
            default_eye_relation,    //
            at_timestamp_ns,         //
            view_type,               //
            view_count,              //
            out_head_relation,       //
            out_fovs,                //
            out_poses);              //
}
 
/*!
 * Helper function for @ref xrt_device::compute_distortion.
 *
 * @copydoc xrt_device::compute_distortion
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_compute_distortion(
    struct xrt_device *xdev, uint32_t view, float u, float v, struct xrt_uv_triplet *out_result)
{
        return xdev->compute_distortion(xdev, view, u, v, out_result);
}
 
/*!
 * Helper function for @ref xrt_device::get_visibility_mask.
 *
 * @copydoc xrt_device::get_visibility_mask
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_visibility_mask(struct xrt_device *xdev,
                               enum xrt_visibility_mask_type type,
                               uint32_t view_index,
                               struct xrt_visibility_mask **out_mask)
{
        return xdev->get_visibility_mask(xdev, type, view_index, out_mask);
}
 
/*!
 * Helper function for @ref xrt_device::ref_space_usage.
 *
 * @copydoc xrt_device::ref_space_usage
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_ref_space_usage(struct xrt_device *xdev,
                           enum xrt_reference_space_type type,
                           enum xrt_input_name name,
                           bool used)
{
        return xdev->ref_space_usage(xdev, type, name, used);
}
 
/*!
 * Helper function for @ref xrt_device::is_form_factor_available.
 *
 * @copydoc xrt_device::is_form_factor_available
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_is_form_factor_available(struct xrt_device *xdev, enum xrt_form_factor form_factor, bool *out_available)
{
        return xdev->is_form_factor_available(xdev, form_factor, out_available);
}
 
/*!
 * Helper function for @ref xrt_device::get_battery_status.
 *
 * @copydoc xrt_device::get_battery_status
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_battery_status(struct xrt_device *xdev, bool *out_present, bool *out_charging, float *out_charge)
{
        return xdev->get_battery_status(xdev, out_present, out_charging, out_charge);
}
 
/*!
 * Helper function for @ref xrt_device::get_brightness.
 *
 * @copydoc xrt_device::get_brightness
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_brightness(struct xrt_device *xdev, float *out_brightness)
{
        return xdev->get_brightness(xdev, out_brightness);
}
 
/*!
 * Helper function for @ref xrt_device::set_brightness.
 *
 * @copydoc xrt_device::set_brightness
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_set_brightness(struct xrt_device *xdev, float brightness, bool relative)
{
        return xdev->set_brightness(xdev, brightness, relative);
}
 
/*!
 * Helper function for @ref xrt_device::get_compositor_info.
 *
 * @copydoc xrt_device::get_compositor_info
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_get_compositor_info(struct xrt_device *xdev,
                               const struct xrt_device_compositor_mode *mode,
                               struct xrt_device_compositor_info *out_info)
{
        return xdev->get_compositor_info(xdev, mode, out_info);
}
 
/*!
 * Helper function for @ref xrt_device::begin_feature.
 *
 * @copydoc xrt_device::begin_feature
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_begin_feature(struct xrt_device *xdev, enum xrt_device_feature_type type)
{
        return xdev->begin_feature(xdev, type);
}
 
/*!
 * Helper function for @ref xrt_device::end_feature.
 *
 * @copydoc xrt_device::end_feature
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline xrt_result_t
xrt_device_end_feature(struct xrt_device *xdev, enum xrt_device_feature_type type)
{
        return xdev->end_feature(xdev, type);
}
 
/*!
 * Helper function for @ref xrt_device::destroy.
 *
 * Handles nulls, sets your pointer to null.
 *
 * @public @memberof xrt_device
 */
XRT_NONNULL_ALL static inline void
xrt_device_destroy(struct xrt_device **xdev_ptr)
{
        struct xrt_device *xdev = *xdev_ptr;
        if (xdev == NULL) {
                return;
        }
 
        xdev->destroy(xdev);
        *xdev_ptr = NULL;
}
 
 
#ifdef __cplusplus
} // extern "C"
#endif