class SetCameraPoseBufferCmd
Defined at line 1509 of file fidling/gen/sdk/fidl/fuchsia.ui.gfx/fuchsia.ui.gfx/cpp/fidl/fuchsia.ui.gfx/cpp/natural_types.h
Sets the "pose buffer" for the camera identified by `camera_id`.
This operation can be applied to both Cameras and StereoCameras.
This will override any position and rotation set for the camera and will
make it take its position and rotation from the pose buffer each frame
based on the presentation time for that frame.
A pose buffer represents a ring buffer of poses for a fixed number of time
points in the future. Each entry in the buffer identified by `buffer_id` is
a quaternion and a position layed out as follows:
struct Pose {
// Quaternion
float32 a;
float32 b;
float32 c;
float32 d;
// Position
float32 x;
float32 y;
float32 z;
// Reserved/Padding
byte[4] reserved;
}
The buffer can be thought of as a packed array of `num_entries` Pose structs
and is required to be at least num_entries * sizeof(Pose) bytes.
The quaternions and positions are specified in the space of the camera's
parent node.
`base_time` is a base time point expressed in nanoseconds in the
`CLOCK_MONOTONIC` timebase and `time_interval` is the time in nanoseconds
between entries in the buffer. `base_time` must be in the past.
For a given point in time `t` expressed in nanoseconds in the
`CLOCK_MONOTONIC` timebase the index of the corresponding pose in
the pose buffer can be computed as follows:
index(t) = ((t - base_time) / time_interval) % num_entries
poses[index(t)] is valid for t over the time interval (t - time_interval, t]
and should be expected to updated continuously without synchronization
for the duration of that interval. If a single pose value is needed for
multiple non-atomic operations a value should be latched and stored outside
the pose buffer.
Because the poses are not protected by any synchronization primitives it is
possible that when a pose is latched it will be only partially updated, and
the pose being read will contain some components from the pose before it is
updated and some components from the updated pose. The safety of using these
"torn" poses relies on two things:
1) Sequential poses written to poses[index(t)] are very similar to each
other numerically, so that if some components are taken from the first and
some are taken from another the result is numerically similar to both
2) The space of positions and quaternions is locally flat at the scale of
changes between sequential updates, which guarantees that two poses which
are numerically similar also represent semantically similar poses (i.e.
there are no discontinuities which will cause a small numerical change in
the position or quaterninon to cause a large change in the encoded pose)
For positions this is guaranteed because Scenic uses a Euclidean 3-space
which is globally flat and for quaternions this is guaranteed because
quaternions encode rotation as points on a unit 4-sphere, and spheres are
locally flat. For more details on the encoding of rotations in quaterions
see https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation
This commanderation is intended for late latching camera pose to support
low-latency motion-tracked rendering.
Public Methods
void SetCameraPoseBufferCmd (uint32_t camera_id, uint32_t buffer_id, uint32_t num_entries, int64_t base_time, uint64_t time_interval)void SetCameraPoseBufferCmd ()Default constructs a |SetCameraPoseBufferCmd| only if all of its members are default constructible.
Defined at line 1519 of file fidling/gen/sdk/fidl/fuchsia.ui.gfx/fuchsia.ui.gfx/cpp/fidl/fuchsia.ui.gfx/cpp/natural_types.h
void SetCameraPoseBufferCmd (SetCameraPoseBufferCmd && )Defined at line 1522 of file fidling/gen/sdk/fidl/fuchsia.ui.gfx/fuchsia.ui.gfx/cpp/fidl/fuchsia.ui.gfx/cpp/natural_types.h
void SetCameraPoseBufferCmd (Storage_ storage)void SetCameraPoseBufferCmd (const SetCameraPoseBufferCmd & other)SetCameraPoseBufferCmd & operator= (const SetCameraPoseBufferCmd & other)bool operator== (const SetCameraPoseBufferCmd & other)bool operator!= (const SetCameraPoseBufferCmd & other)uint32_t camera_id ()uint32_t & camera_id ()SetCameraPoseBufferCmd & camera_id (uint32_t value)Setter for camera_id.
uint32_t buffer_id ()uint32_t & buffer_id ()SetCameraPoseBufferCmd & buffer_id (uint32_t value)Setter for buffer_id.
uint32_t num_entries ()uint32_t & num_entries ()SetCameraPoseBufferCmd & num_entries (uint32_t value)Setter for num_entries.
int64_t base_time ()int64_t & base_time ()SetCameraPoseBufferCmd & base_time (int64_t value)Setter for base_time.
SetCameraPoseBufferCmd & operator= (SetCameraPoseBufferCmd && )Defined at line 1523 of file fidling/gen/sdk/fidl/fuchsia.ui.gfx/fuchsia.ui.gfx/cpp/fidl/fuchsia.ui.gfx/cpp/natural_types.h
uint64_t time_interval ()uint64_t & time_interval ()SetCameraPoseBufferCmd & time_interval (uint64_t value)Setter for time_interval.
void SetCameraPoseBufferCmd (::fidl::internal::DefaultConstructPossiblyInvalidObjectTag )Friends
class MemberVisitorclass NaturalStructCodingTraits