Frame

Per-frame state.

Summary

Typedefs
ArFrame	typedef struct ArFrame_ The world state resulting from an update (value type).

Functions
ArFrame_acquireCamera(const ArSession *session, const ArFrame *frame, ArCamera **out_camera)	void Returns the camera object for the session.
ArFrame_acquireImageMetadata(const ArSession *session, const ArFrame *frame, ArImageMetadata **out_metadata)	ArStatus Gets the camera metadata for the current camera image.
ArFrame_acquirePointCloud(const ArSession *session, const ArFrame *frame, ArPointCloud **out_point_cloud)	ArStatus Acquires the current set of estimated 3d points attached to real-world geometry.
ArFrame_create(const ArSession *session, ArFrame **out_frame)	void Allocates a new ArFrame object, storing the pointer into *out_frame.
ArFrame_destroy(ArFrame *frame)	void Releases an ArFrame and any references it holds.
ArFrame_getDisplayGeometryChanged(const ArSession *session, const ArFrame *frame, int32_t *out_geometry_changed)	void Checks if the display rotation or viewport geometry changed since the previous call to ArSession_update().
ArFrame_getLightEstimate(const ArSession *session, const ArFrame *frame, ArLightEstimate *out_light_estimate)	void Gets the current ambient light estimate, if light estimation was enabled.
ArFrame_getTimestamp(const ArSession *session, const ArFrame *frame, int64_t *out_timestamp_ns)	void Returns the timestamp in nanoseconds when this image was captured.
ArFrame_getUpdatedAnchors(const ArSession *session, const ArFrame *frame, ArAnchorList *out_anchor_list)	void Gets the set of anchors that were changed by the ArSession_update() that produced this Frame.
ArFrame_getUpdatedTrackables(const ArSession *session, const ArFrame *frame, ArTrackableType filter_type, ArTrackableList *out_trackable_list)	void Gets the set of trackables of a particular type that were changed by the ArSession_update() call that produced this Frame.
ArFrame_hitTest(const ArSession *session, const ArFrame *frame, float pixel_x, float pixel_y, ArHitResultList *hit_result_list)	void Performs a ray cast from the user's device in the direction of the given location in the camera view.
ArFrame_transformDisplayUvCoords(const ArSession *session, const ArFrame *frame, int32_t num_elements, const float *uvs_in, float *uvs_out)	void Transform the given texture coordinates to correctly show the background image.

Typedefs

ArFrame

struct ArFrame_ ArFrame

The world state resulting from an update (value type).

Allocate with ArFrame_create()
Populate with ArSession_update()
Release with ArFrame_destroy()

Functions

ArFrame_acquireCamera

void ArFrame_acquireCamera(
  const ArSession *session,
  const ArFrame *frame,
  ArCamera **out_camera
)

Returns the camera object for the session.

Note that this Camera instance is long-lived so the same instance is returned regardless of the frame object this method was called on.

ArFrame_acquireImageMetadata

ArStatus ArFrame_acquireImageMetadata(
  const ArSession *session,
  const ArFrame *frame,
  ArImageMetadata **out_metadata
)

Gets the camera metadata for the current camera image.

Details
Returns	AR_SUCCESS or any of: AR_ERROR_DEADLINE_EXCEEDED if frame is not the latest frame from by ArSession_update(). AR_ERROR_RESOURCE_EXHAUSTED if too many metadata objects are currently held. AR_ERROR_NOT_YET_AVAILABLE if the camera failed to produce metadata for the given frame. Note: this will commonly happen for few frames right after ArSession_resume() due to the camera stack bringup.

ArFrame_acquirePointCloud

ArStatus ArFrame_acquirePointCloud(
  const ArSession *session,
  const ArFrame *frame,
  ArPointCloud **out_point_cloud
)

Acquires the current set of estimated 3d points attached to real-world geometry.

A matching call to PointCloud_release() must be made when the application is done accessing the point cloud.

Note: This information is for visualization and debugging purposes only. Its characteristics and format are subject to change in subsequent versions of the API.

Details
Parameters	session The ARCore session. frame The current frame. out_point_cloud Pointer to an ArPointCloud* receive the address of the point cloud.
Returns	AR_SUCCESS or any of: AR_ERROR_DEADLINE_EXCEEDED if frame is not the latest frame from by ArSession_update(). AR_ERROR_RESOURCE_EXHAUSTED if too many point clouds are currently held.

ArFrame_create

void ArFrame_create(
  const ArSession *session,
  ArFrame **out_frame
)

Allocates a new ArFrame object, storing the pointer into *out_frame.

Note: the same ArFrame can be used repeatedly when calling ArSession_update.

ArFrame_destroy

void ArFrame_destroy(
  ArFrame *frame
)

Releases an ArFrame and any references it holds.

ArFrame_getDisplayGeometryChanged

void ArFrame_getDisplayGeometryChanged(
  const ArSession *session,
  const ArFrame *frame,
  int32_t *out_geometry_changed
)

Checks if the display rotation or viewport geometry changed since the previous call to ArSession_update().

The application should re-query ArCamera_getProjectionMatrix() and ArFrame_transformDisplayUvCoords() whenever this emits non-zero.

ArFrame_getLightEstimate

void ArFrame_getLightEstimate(
  const ArSession *session,
  const ArFrame *frame,
  ArLightEstimate *out_light_estimate
)

Gets the current ambient light estimate, if light estimation was enabled.

Details
Parameters	session The ARCore session. frame The current frame. out_light_estimate The light estimate to fill. This object must have been previously created with ArLightEstimate_create().

ArFrame_getTimestamp

void ArFrame_getTimestamp(
  const ArSession *session,
  const ArFrame *frame,
  int64_t *out_timestamp_ns
)

Returns the timestamp in nanoseconds when this image was captured.

This can be used to detect dropped frames or measure the camera frame rate. The time base of this value is specifically not defined, but it is likely similar to clock_gettime(CLOCK_BOOTTIME).

ArFrame_getUpdatedAnchors

void ArFrame_getUpdatedAnchors(
  const ArSession *session,
  const ArFrame *frame,
  ArAnchorList *out_anchor_list
)

Gets the set of anchors that were changed by the ArSession_update() that produced this Frame.

Details
Parameters	session The ARCore session frame The current frame. out_anchor_list The list to fill. This list must have already been allocated with ArAnchorList_create(). If previously used, the list will first be cleared.

ArFrame_getUpdatedTrackables

void ArFrame_getUpdatedTrackables(
  const ArSession *session,
  const ArFrame *frame,
  ArTrackableType filter_type,
  ArTrackableList *out_trackable_list
)

Gets the set of trackables of a particular type that were changed by the ArSession_update() call that produced this Frame.

Details
Parameters	session The ARCore session frame The current frame. filter_type The type(s) of trackables to return. See ArTrackableType for legal values. out_trackable_list The list to fill. This list must have already been allocated with ArTrackableList_create(). If previously used, the list will first be cleared.

ArFrame_hitTest

void ArFrame_hitTest(
  const ArSession *session,
  const ArFrame *frame,
  float pixel_x,
  float pixel_y,
  ArHitResultList *hit_result_list
)

Performs a ray cast from the user's device in the direction of the given location in the camera view.

Intersections with detected scene geometry are returned, sorted by distance from the device; the nearest intersection is returned first.

Note: Significant geometric leeway is given when returning hit results. For example, a plane hit may be generated if the ray came close, but did not actually hit within the plane extents or plane bounds (ArPlane_isPoseInExtents() and ArPlane_isPoseInPolygon() can be used to determine these cases). A point (point cloud) hit is generated when a point is roughly within one finger-width of the provided screen coordinates.

The resulting list is ordered by distance, with the nearest hit first

Note: If not tracking, the hit_result_list will be empty.
Note: If called on an old frame (not the latest produced by ArSession_update() the hit_result_list will be empty).

Details
Parameters	session The ARCore session. frame The current frame. pixel_x Logical X position within the view, as from an Android UI event. pixel_y Logical X position within the view. hit_result_list The list to fill. This list must have been previously allocated using ArHitResultList_create(). If the list has been previously used, it will first be cleared.

ArFrame_transformDisplayUvCoords

void ArFrame_transformDisplayUvCoords(
  const ArSession *session,
  const ArFrame *frame,
  int32_t num_elements,
  const float *uvs_in,
  float *uvs_out
)

Transform the given texture coordinates to correctly show the background image.

This will account for the display rotation, and any additional required adjustment. For performance, this function should be called only if ArFrame_hasDisplayGeometryChanged() emits true.

Details
Parameters	session The ARCore session frame The current frame. num_elements The number of floats to transform. Must be a multiple of 2. uvs_in and uvs_out must point to arrays of at least this many floats. uvs_in Input UV coordinates in normalized screen space. uvs_out Output UV coordinates in texture coordinates.