xrt: Devices get a timekeeping object, must return a timestamp.

Updates drivers to match.

src/xrt/drivers/hdk/hdk_device.cpp

@@ -28,6 +28,7 @@
 #include "util/u_debug.h"
 #include "util/u_misc.h"
 #include "util/u_device.h"
+#include "util/u_time.h"
 
 #include "hdk_device.h"
 
@@ -99,11 +100,14 @@ hdk_device_destroy(struct xrt_device *xdev)
 
 static void
 hdk_device_get_tracked_pose(struct xrt_device *xdev,
+                            struct time_state *timekeeping,
+                            int64_t *out_timestamp,
                             struct xrt_space_relation *out_relation)
 {
 	struct hdk_device *hd = hdk_device(xdev);
 
 	uint8_t buffer[32];
+	int64_t now = time_state_get_now(timekeeping);
 	auto bytesRead = hid_read(hd->dev, &(buffer[0]), sizeof(buffer));
 	if (bytesRead == -1) {
 		if (!hd->disconnect_notified) {
@@ -121,6 +125,8 @@ hdk_device_get_tracked_pose(struct xrt_device *xdev,
 		out_relation->relation_flags = XRT_SPACE_RELATION_BITMASK_NONE;
 		return;
 	}
+	//! @todo adjust for latency here
+	*out_timestamp = now;
 	uint8_t *buf = &(buffer[0]);
 
 #if 0

src/xrt/drivers/ohmd/oh_device.c

@@ -20,6 +20,7 @@
 #include "util/u_misc.h"
 #include "util/u_debug.h"
 #include "util/u_device.h"
+#include "util/u_time.h"
 
 #include "oh_device.h"
 
@@ -41,11 +42,16 @@ oh_device_destroy(struct xrt_device *xdev)
 
 static void
 oh_device_get_tracked_pose(struct xrt_device *xdev,
+                           struct time_state *timekeeping,
+                           int64_t *out_timestamp,
                            struct xrt_space_relation *out_relation)
 {
 	struct oh_device *ohd = oh_device(xdev);
 	struct xrt_quat quat = {0.f, 0.f, 0.f, 1.f};
 	ohmd_ctx_update(ohd->ctx);
+	int64_t now = time_state_get_now(timekeeping);
+	//! @todo adjust for latency here
+	*out_timestamp = now;
 	ohmd_device_getf(ohd->dev, OHMD_ROTATION_QUAT, &quat.x);
 	out_relation->pose.orientation = quat;
 	//! @todo assuming that orientation is actually currently tracked.

src/xrt/include/xrt/xrt_device.h

@@ -15,6 +15,7 @@
 extern "C" {
 #endif
 
+struct time_state;
 
 /*!
  * A per-lens view information.
@@ -153,6 +154,8 @@ struct xrt_device
 	 * This is very very WIP and will need to be made a lot more advanced.
 	 */
 	void (*get_tracked_pose)(struct xrt_device *xdev,
+	                         struct time_state *timekeeping,
+	                         int64_t *out_timestamp,
 	                         struct xrt_space_relation *out_relation);
 
 	/*!

src/xrt/state_trackers/oxr/oxr_session.c

@@ -135,7 +135,9 @@ oxr_session_get_view_pose_at(struct oxr_logger *log,
 
 	struct xrt_device *xdev = sess->sys->device;
 	struct xrt_space_relation relation;
-	xdev->get_tracked_pose(xdev, &relation);
+	int64_t timestamp;
+	xdev->get_tracked_pose(xdev, sess->sys->inst->timekeeping, &timestamp,
+	                       &relation);
 	if ((relation.relation_flags &
 	     XRT_SPACE_RELATION_ORIENTATION_VALID_BIT) != 0) {
 		pose->orientation = relation.pose.orientation;