Constantly read parameters from an external file to manipulate functions in Stellarium using its script engine.

[FogoVoar]

I have a project in mind that involves manipulating the yaw and pitch of the Stellarium camera using values ​​from another program (which can be saved in a file using any format).

I realized that for security reasons Stellarium's script engine doesn't allow manipulating files, but it does allow including them, so this was my attempt:

With my external program I create the following input.inc where the values ​​change every second:

var pitch = 45;
var yaw = 90;

In the Stellarium console I try to repeatedly include the file:

function refresh() {
	include("input.inc");
	core.moveToAltAzi(pitch, yaw, 0);
	core.wait(5);
	refresh();
}
refresh()

all I get is:

script error: 'Reference'  @ line 2: ReferenceError: include is not defined

which is weird because include works (once) if placed outside the function scope.
Does anyone have any idea of ​​a better approach?

[gzotti]

Obvious solution: place include outside the function scope. Maybe rewrite as refresh(pitch, yaw);

[FogoVoar]

include("input.inc");
function refresh() {
	core.moveToAltAzi(pitch, yaw, 0);
	core.wait(2);
	refresh();
}
refresh()

in this case include will only be included once and successive changes to input.inc will have no effect.
Rewriting it as refresh(pitch, yaw); would put it in a locked loop where the pitch and yaw value would never change.

[gzotti]

I did not see the application context of the whole thing. include is a non-standard preprocessing command executed before actually starting the script, so it cannot be used to read dynamically changing files.

[10110111]

You could just generate the whole function body instead of just the declarations of variables.

[gzotti]

OK, if there is a general way of reading just any input files from anywhere, I am unaware of it. This example may be much simpler by just calling, from the external program, the RemoteControl API with curl (or of course directly).

[10110111]

Apparently, the typical way to read files from JS is by using XMLHttpRequest. But it's not available in QtScript. So it's impossible not for security reasons, but simply due to a lack of implementation.

[FogoVoar]

OK, if there is a general way of reading just any input files from anywhere, I am unaware of it. This example may be much simpler by just calling, from the external program, the RemoteControl API with curl (or of course directly).

I wasn't aware of the RemoteControl API, I enabled the plugin and started the server on port 20180, with the curl command it seems to be able to access the API, but I have not yet had success in manipulating stellarium or obtaining data.

this is the command I'm trying:
curl --data 'j2000=[0.5,0.3,0.2]' http://192.168.0.104:20180/api/main/view --output log.txt
it returns curl: (1) Received HTTP/0.9 when not allowed

by appending --http0.9 like:
curl --http0.9 --data 'j2000=[0.5,0.3,0.2]' http://192.168.0.104:20180/api/main/view --output log.txt
the log.txt returns:

� 5StellariumSyncPluginProtocol�   � �� È�°ª
#Gm˜ê廕p‡l  �   �invalid message type 80

(it also only appears to work if I specify my machine address directly, not with localhost).

[gzotti]

I don't understand why there is a complaint about HTTP/0.9, never seen that. I can call
curl --data 'j2000=[0.5,0.3,0.2]' http://192.168.xxx.xxx:8090/api/main/view
from my WSL console (Ubuntu 22.04.04, curl 7.81.0) and it just works. --http0.9 or --http1.0 also work, --http2.0 does not work.

[FogoVoar]

Hm, weird, I'm running WSL with Ubuntu 22.04.3 and curl 7.81.0 (and Stellarium 24.1).
Thanks anyway! for now I'm going to shelve the idea, hopefully someone in the future can revive this thread with some workaround.

[FogoVoar]

As @gzotti suggested, it is possible to achieve this by using the RemoteControl plugin to start a server with an API for Stellarium functions.
Press F2 > Plugins > Remote Control > Load at startup > configure > [x] Server enabled
If the configure button is unavailable, simply restart Stellarium.

To send the commands you will need to send HTTP requests using something like fetch or axios (both comes by default in nodejs), or curl.

In the RemoteControl documentation you can find the "view" field which has 3 functions to rotate the camera:

    "j2000" : "[x,y,z]",
    "jNow"  : "[x,y,z]",
    "altAz" : "[x,y,z]"

To call the function with parameters you must follow this format:
j2000=[0.5,0.3,0.2]

Example with curl:
curl --data 'j2000=[0.5,0.3,0.2]' http://192.168.xxx.xxx:8090/api/main/view In the IP field you will define the IP of the machine that is running the Stellarium server (in this case it is our local IP, you can use ipconfig to find it).

Example with nodejs fetch:

const url = 'http://192.168.xxx.xxx:20180/api/main/view?j2000=[0.5,0.3,0.2]';
fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    }
  })
  .then(response => {
    response.text().then(text => console.log('Raw response:', text));
    return response.json();
  })

That's all you need.

Regarding the issue with "Received HTTP/0.9 when not allowed" or "invalid message type", it was resolved here.

[gzotti]

Thanks for the Node.js sample. Can I add that into the User Guide?

[FogoVoar]

Thanks for the Node.js sample. Can I add that into the User Guide?

Sure!