# Source code for napari.components.camera

```
import warnings
from typing import Optional, Tuple
import numpy as np
from pydantic import validator
from scipy.spatial.transform import Rotation as R
from napari.utils.events import EventedModel
from napari.utils.misc import ensure_n_tuple
from napari.utils.translations import trans
[docs]class Camera(EventedModel):
"""Camera object modeling position and view of the camera.
Attributes
----------
center : 3-tuple
Center of rotation for the camera.
In 2D viewing the last two values are used.
zoom : float
Scale from canvas pixels to world pixels.
angles : 3-tuple
Euler angles of camera in 3D viewing (rx, ry, rz), in degrees.
Only used during 3D viewing.
Note that Euler angles's intrinsic degeneracy means different
sets of Euler angles may lead to the same view.
perspective : float
Perspective (aka "field of view" in vispy) of the camera (if 3D).
interactive : bool
If the camera mouse pan/zoom is enabled or not.
This attribute is deprecated since 0.5.0 and should not be used.
Use the mouse_pan and mouse_zoom attributes instead.
mouse_pan : bool
If the camera interactive panning with the mouse is enabled or not.
mouse_zoom : bool
If the camera interactive zooming with the mouse is enabled or not.
"""
# fields
center: Tuple[float, float, float] = (0.0, 0.0, 0.0)
zoom: float = 1.0
angles: Tuple[float, float, float] = (0.0, 0.0, 90.0)
perspective: float = 0
mouse_pan: bool = True
mouse_zoom: bool = True
# validators
@validator('center', 'angles', pre=True)
def _ensure_3_tuple(v):
return ensure_n_tuple(v, n=3)
@property
def view_direction(self) -> Tuple[float, float, float]:
"""3D view direction vector of the camera.
View direction is calculated from the Euler angles and returned as a
3-tuple. This direction is in 3D scene coordinates, the world coordinate
system for three currently displayed dimensions.
"""
ang = np.deg2rad(self.angles)
view_direction = (
np.sin(ang[2]) * np.cos(ang[1]),
np.cos(ang[2]) * np.cos(ang[1]),
-np.sin(ang[1]),
)
return view_direction
@property
def up_direction(self) -> Tuple[float, float, float]:
"""3D direction vector pointing up on the canvas.
Up direction is calculated from the Euler angles and returned as a
3-tuple. This direction is in 3D scene coordinates, the world coordinate
system for three currently displayed dimensions.
"""
rotation_matrix = R.from_euler(
seq='yzx', angles=self.angles, degrees=True
).as_matrix()
return tuple(rotation_matrix[:, 2][::-1])
[docs] def set_view_direction(
self,
view_direction: Tuple[float, float, float],
up_direction: Tuple[float, float, float] = (0, -1, 0),
):
"""Set camera angles from direction vectors.
Both the view direction and the up direction are specified in 3D scene
coordinates, the world coordinate system for three currently displayed
dimensions.
The provided up direction must not be parallel to the provided
view direction. The provided up direction does not need to be orthogonal
to the view direction. The final up direction will be a vector orthogonal
to the view direction, aligned with the provided up direction.
Parameters
----------
view_direction : 3-tuple of float
The desired view direction vector in 3D scene coordinates, the world
coordinate system for three currently displayed dimensions.
up_direction : 3-tuple of float
A direction vector which will point upwards on the canvas. Defaults
to (0, -1, 0) unless the view direction is parallel to the y-axis,
in which case will default to (-1, 0, 0).
"""
# default behaviour of up direction
view_direction_along_y_axis = (
view_direction[0],
view_direction[2],
) == (0, 0)
up_direction_along_y_axis = (up_direction[0], up_direction[2]) == (
0,
0,
)
if view_direction_along_y_axis and up_direction_along_y_axis:
up_direction = (-1, 0, 0) # align up direction along z axis
# xyz ordering for vispy, normalise vectors for rotation matrix
view_direction = np.asarray(view_direction, dtype=float)[::-1]
view_direction /= np.linalg.norm(view_direction)
up_direction = np.asarray(up_direction, dtype=float)[::-1]
up_direction = np.cross(view_direction, up_direction)
up_direction /= np.linalg.norm(up_direction)
# explicit check for parallel view direction and up direction
if np.allclose(np.cross(view_direction, up_direction), 0):
raise ValueError(
trans._(
"view direction and up direction are parallel",
deferred=True,
)
)
x_direction = np.cross(up_direction, view_direction)
x_direction /= np.linalg.norm(x_direction)
# construct rotation matrix, convert to euler angles
rotation_matrix = np.column_stack(
(up_direction, view_direction, x_direction)
)
euler_angles = R.from_matrix(rotation_matrix).as_euler(
seq='yzx', degrees=True
)
self.angles = euler_angles
[docs] def calculate_nd_view_direction(
self, ndim: int, dims_displayed: Tuple[int]
) -> np.ndarray:
"""Calculate the nD view direction vector of the camera.
Parameters
----------
ndim : int
Number of dimensions in which to embed the 3D view vector.
dims_displayed : Tuple[int]
Dimensions in which to embed the 3D view vector.
Returns
-------
view_direction_nd : np.ndarray
nD view direction vector as an (ndim, ) ndarray
"""
if len(dims_displayed) != 3:
return None
view_direction_nd = np.zeros(ndim)
view_direction_nd[list(dims_displayed)] = self.view_direction
return view_direction_nd
[docs] def calculate_nd_up_direction(
self, ndim: int, dims_displayed: Tuple[int]
) -> Optional[np.ndarray]:
"""Calculate the nD up direction vector of the camera.
Parameters
----------
ndim : int
Number of dimensions in which to embed the 3D view vector.
dims_displayed : Tuple[int]
Dimensions in which to embed the 3D view vector.
Returns
-------
up_direction_nd : np.ndarray
nD view direction vector as an (ndim, ) ndarray
"""
if len(dims_displayed) != 3:
return None
up_direction_nd = np.zeros(ndim)
up_direction_nd[list(dims_displayed)] = self.up_direction
return up_direction_nd
@property
def interactive(self) -> bool:
warnings.warn(
'`Camera.interactive` is deprecated since 0.5.0 and will be removed in 0.6.0.',
category=DeprecationWarning,
)
return self.mouse_pan or self.mouse_zoom
@interactive.setter
def interactive(self, interactive: bool):
warnings.warn(
'`Camera.interactive` is deprecated since 0.5.0 and will be removed in 0.6.0.',
category=DeprecationWarning,
)
self.mouse_pan = interactive
self.mouse_zoom = interactive
```