XPLMCamera

To use:

import xp

Theory Of Operation

The XPLMCamera APIs allow plug-ins to control the camera angle in X-Plane. This has a number of applications, including but not limited to:

  • Creating new views (including dynamic/user-controllable views) for the user.

  • Creating applications that use X-Plane as a renderer of scenery, aircrafts, or both.

The camera is controlled via six parameters: a location in OpenGL coordinates (i.e., x, y and z) pitch, roll and yaw, similar to an airplane’s position. OpenGL coordinate info is described in detail in the XPLMGraphics documentation; generally you should use the XPLMGraphics routines to convert from world to local coordinates. The camera’s orientation starts facing level with the ground directly up the negative-Z axis (approximately north) with the horizon horizontal. It is then rotated clockwise for yaw, pitched up for positive pitch, and rolled clockwise around the vector it is looking along for roll.

You control the camera either either until the user selects a new view or permanently (the later being similar to how UDP camera control works). You control the camera by registering a callback per frame from which you calculate the new camera positions. This guarantees smooth camera motion.

Use the XPLMDataAccess APIs to get information like the position of the aircraft, etc. for complex camera positioning.

Note

if your goal is to move the virtual pilot in the cockpit, this API is not needed; simply update the datarefs for the pilot’s head position.

For custom exterior cameras, set the camera’s mode to an external view first to get correct sound and 2-d panel behavior.

Functions

controlCamera(howLong=ControlCameraUntilViewChanges, controlFunc=None, refCon=None)

Repositions the camera on the next drawing cycle.

howLong is either ControlCameraUntilViewChanges which controls until the view is set by some other means, or ControlCameraForever which controls until the plugin exits, releases control (dontControlCamera()) or control is forcibly taken by another plugin.

controlFunc is your callback, called during draw cycle. It will be called with three parameters:
  • position: list of seven floats

    • x, y, z (OpenGL position)

    • pitch

    • heading

    • roll

    • zoom

    Update one or more values in the list to change position, and return 1. Zero return indicates you do not want to change position, and you relinquish control.

    Note

    Laminar says position list values are undefined on input, so you should call readCameraPosition() and update the position accordingly. (In practice, it appears position is initialized with the correct information, but this is not guaranteed.)

    Do not create a new position list, you need to update the container provided, so the calling function has the same pointer to the data structure:

    # THIS WILL FAIL -- the value for 'position' is changed
def myControlFunc(position, isLosingControl, refCon):
    position = xp.readCameraPosition()
    position[4] = position[4] + 0.5
    ...

# THIS WORKS -- the value is unchanged, the contents are changed
def myControlFunc(position, isLosingControl, refCon):
    position.clear()
    position.extend(xp.readCameraPosition())
    position[4] = position[4] + 0.5
    ...
  • isLosingControl:

    • 1 if you are losing control, 0 otherwise

  • refCon:

    • reference constant you provided with call to controlCamera()

The final refCon is a reference constant passed to your controlFunc(). Only controlFunc parameter is required.

>>> def myControlFunc(position, isLosingControl, refCon):
...     if isLosingControl:
...         xp.dontControlCamera()
...     else:
...         currentPosition = xp.readCameraPosition()
...     position.clear()  # (it's an undefined list on entry)
...     position.extend(currentPosition)
...     position[4] = currentPosition[4] + 0.5  # i.e., 'heading'.. spin camera .5 degrees @ frame
...
...     if position[4] > 270.0:
...         xp.dontControlCamera()  # and stop spin and release camera once we're facing West
...         return 0
...     return 1
...
>>> xp.controlCamera(controlFunc=myControlFunc)

Official SDK: XPLMControlCamera

dontControlCamera()

Releases control of camera. (See controlCamera()). You should not use this routine unless you have possession of the camera. (See isCameraBeingControlled()).

(If you call this, X-Plane will not call your camera control function with isLosingControl=1: it will never call your control function again.)

Official SDK: XPLMDontControlCamera

isCameraBeingControlled()

Returns a two element tuple (isBeingControlled, howLong)

isBeingControlled is 1 if the camera is being controlled (by anyone), 0 otherwise. If first element is non-zero, second element matches howLong value provided to controlCamera().

>>> xp.controlCamera(howLong=2, controlFunc=myControlFunc)
>>> xp.isCameraBeingControlled()
(1, 2)
>>> xp.controlCamera(howLong=1, controlFunc=myControlFunc)
>>> xp.isCameraBeingControlled()
(1, 1)
>>> xp.dontControlCamera()
>>> xp.isCameraBeingControlled()
(0, 32644)

Official SDK: XPLMIsCameraBeingControlled

readCameraPosition()

Returns current camera position, a list of seven floats:

Index

Value

Meaning

0,1,2

x, y, z

camera’s position in OpenGL coordinates

3

pitch

In degrees, 0.0 is flat, positive for nose up.

4

heading

In degrees, 0.0 is true north

5

roll

In degrees, 0.0 is flat, positive for roll right

6

zoom

1.0 is normal, 2.0 is 2x zoom (objects appear larger), etc.

You do not need to control the camera in order to read its position:

>>> xp.readCameraPosition()
[-22567.63552, 94.40988, 4305.8530, 2.407667, 180.40255, -0.86660, 1.0]

Official SDK: XPLMReadCameraPosition

Constants

Control Camera Duration

Enumeration states how long you want to retain control of the camera. You can retain it indefinitely or until the user selects a new view. Used by controlCamera() and isCameraBeingControlled(). You can relinquish control by calling dontControlCamera() or returning zero from you controlCamera() callback function.

ControlCameraUntilViewChanges = 1

Camera is controlled until the view is changes (e.g., user requests “External View” from X-Plane menu.)

Official SDK: xplm_ControlCameraUntilViewChanges

ControlCameraForever = 2

Camera is controlled forever.

Official SDK: xplm_ControlCameraForever

Example

See also PI_Camera1.py demo.