OpenCPN PlugIn Development

[onecue]

Hi developers.

I want to test a function connecting to serial port in my plugin.

I know there are functions to connect to serial port in opencpn. How can I use the function? or I need to incorporate some serial communication codes?

The message looks like "$AIBIM,x-accel,y-accel,z-accel,inclination,[0|1],[0|1],*Checksum\r\n" from a device.

[nohal]

onecue...
Why would you do that? The message looks like normal NMEA, so if you need to receive it from a sensor:
- set WANTS_NMEA_SENTENCES flag in the return value of yourplugin_pi::Init
- Implement SetNMEASentence method

If you want to send it out, just call PushNMEABuffer

For reference look at https://github.com/SethDart/vdr_pi/b...src/vdr_pi.cpp

Pavel

[wushinwei]

Hello,
I am a new user of OpenCPN and love it already.
I have followed the windows compilation guidelines and successfully compiled OpenCPN.
Then I want to develop a pluing.
I have spent few days to find info about how can I get star,but nothing use that I find.
Any guide?

Thanks

wushinwei

[nohal]

Wushinwei...
Take any existing plugin and learn from it. Ask if something is not clear. But please try to ask questions that are a bit more atomic than "how do I write a plugin?"

Pavel


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[stn92]

Hi. Could you help me? I very new to plugin development. I trying to develop advanced scaled ship icon(vector, with realistic contour shape). I drew an scaled icon, but it static. It is located a specific screen position and not depends of real ship position and rotation. How can I get the location and rotation data from openCPN and bind the icon to the position of the ship?(Sorry for my English)

[seandepagnier]

You can get the boat position from the SetPositionFixEx callback activated from WANTS_NMEA_EVENTS.

You can find the location to render by passing the location to GetCanvasPixLL


To get magnetic course you would have to decode nmea sentences.

[stn92]

Originally Posted by boat_alexandra

You can get the boat position from the SetPositionFixEx callback activated from WANTS_NMEA_EVENTS.

You can find the location to render by passing the location to GetCanvasPixLL


To get magnetic course you would have to decode nmea sentences.

Thanks, everythink works fine except course. Looks like Plugin ViewPort rotated 90 degrees(Sounds funny, but it` really looks like). I can equalize the difference using a coefficient, but when the ship starts moving (I use the MNEA server emulator), the icon starts acting up. I can`t figure out on which the icon course depends. All variables involved in the process of computing the rotation are equal(i mean variables of openCPN and Plugin).
Code of my Icon Render Method - paste.org.ru

[stn92]

I found the problem.

if (g_pfFix.Sog < 0.2) icon_rad = ((g_pfFix.Hdt + 90.) * PI / 180) + rotate;

- Condition not met because of g_pfFix.Sog gives me -1.#INF instead of 0 for some reason. I simply launch the openCPN with no MNEA server running. Sog Fix shold be 0.

[nohal]

stn92...
Shouldn't you be using pSog in that condition? It seems so looking at

float pSog = g_pfFix.Sog;
if (wxIsNaN(pSog))
    pSog = 0.0;

a couple of lines above...
It would also probably be good to actually feed it with some data if you want to test if it works with data...

Pavel

[stn92]

Originally Posted by nohal

stn92...
Shouldn't you be using pSog in that condition? It seems so looking at

float pSog = g_pfFix.Sog;
if (wxIsNaN(pSog))
    pSog = 0.0;

a couple of lines above...
It would also probably be good to actually feed it with some data if you want to test if it works with data...

Pavel

Yes i should. But i forget to replace g_pfFix.Sog with pSog. Thanks.
I fed the test data, and it works fine.
And, is it posible to overlay plugin icon with original? I mean, i need to plugin layer to be above layer with openCPN icon.

[stn92]

There is another problem. My ship turns into ugly train when starts to move.
Seems like RenderOverlay method is called only when Plugin ViewPort position changes.Or may be not. I'm just guessing.

I created the ShipUpdate method and call it each time the boat position changes.

void UpdateShips(){
	
	
	g_pDC = new ODDC(); //need to pass wxDC &dc into it
	RenderShip(*g_pDC);
}

But it no use without wxDC &dc. And i don`t know where to get it.
Am I on the right way to fix an icon? Or is the problem in something else?

[xentia]

Hi all forum members,

I'm new in openCPN world and i found that great software is very useful. After a few weeks I decide to make my own simple plugin. I have some experience with Visual C++. So - i follow strictly instructions from here:

https://opencpn.org/wiki/dokuwiki/do...ugins_to_debug

I use Visual Studio 2017 community, CMake 3.9.0 GUI
Everything was fine - solution generation was successful, i open it in Visual studio, then build for Win32. But unfortunately - when I copy ready dll plugin file to OpenCPN directory for plugins, he did not recognize it. Mean - "projections" is not in list so I cant enable it. I try to figure it out where is my mistake but...

Kindly thanks to all that will try to help me.

[bdbcat]

xentia...

Have a look at the OpenCPN logfile. This will tell you why the Plugin did not load. Post a copy here if necessary.

Good Luck
Dave

[xentia]

Thank you bdbcat,
I also try this one too:
https://opencpn.org/wiki/dokuwiki/do..._build_windows

also with no problem with cmake and build and same result - open CPN do not recognize DLL. I suppose that i miss something here... but just can't figure it out. So i follow your advice and look in log file. Here is suspected lines:

7:19:17 PM: PlugInManager searching for PlugIns in location C:\Program Files (x86)\OpenCPN\plugins
7:19:17 PM: PlugInManager: Loading PlugIn: C:\Program Files (x86)\OpenCPN\plugins\DR_pi.dll
7:19:17 PM: Error: Failed to load shared library 'C:\Program Files (x86)\OpenCPN\plugins\DR_pi.dll' (error 126: the specified module could not be found.)
7:19:17 PM: PlugInManager: Cannot load library: C:\Program Files (x86)\OpenCPN\plugins\DR_pi.dll

Thank you in advance

[xentia]

And here is my try with another one. I've decided to try this:

https://opencpn.org/wiki/dokuwiki/do...ugins_to_debug

with newest openCPN - 4.6.2 - beta

same result

7:30:18 PM: PlugInManager: Loading PlugIn: C:\Program Files (x86)\OpenCPN 4.6.2\plugins\projections_pi.dll
7:30:18 PM: Error: Failed to load shared library 'C:\Program Files (x86)\OpenCPN 4.6.2\plugins\projections_pi.dll' (error 126: the specified module could not be found.)
7:30:18 PM: PlugInManager: Cannot load library: C:\Program Files (x86)\OpenCPN 4.6.2\plugins\projections_pi.dll