pdk addon to display weather data

[MerAB]

Hello,

I attempted to make a small weather add-on which would write the variable values accessible through WeatherSystem interface to a text file. But I could not get it to work - while the addon is added, the text file is not created on load. Could you guide me on what i am missing?
The c++ code looks like this:

#include "stdafx.h"
#include "initpdk.h"
#include "PdkPlugin.h"

#include <WinError.h>

#include <string>
#include<iostream>
using std::cerr;
using std::endl;
#include<fstream>
using std:fstream;
#include<cstdlib>

using namespace P3D;

class SystemReadyCallback : public ICallbackV400
{
public:
SystemReadyCallback() :
m_RefCount(1)
{
}

virtual void Invoke(IParameterListV400* pParams) override;

DEFAULT_REFCOUNT_INLINE_IMPL()
DEFAULT_IUNKNOWN_QI_INLINE_IMPL(ICallbackV400, IID_ICallbackV400)


};

void SystemReadyCallback::Invoke(IParameterListV400* pParams)
{
if (!pParams)
{
return;
}

const static wchar_t* S_NAME = L"Virtual Cockpit - View 00";

// This callback indicate that Prepar3D finish loading
UINT64 messageID = pParams->GetParameter(0).Value;
if (messageID == EVENT_MESSAGE_LOADING_COMPLETE)
{
ofstream outdata;

// Get the window plugin system
//CComPtr<IWindowPluginSystem> spPluginSystem = PdkServices::GetWindowPluginSystem();
CComPtr<IWeatherSystemV430> weatherSystem = PdkServices::GetWeatherSystem();
if (weatherSystem != NULL)
{
outdata.open("weatherdata.txt");
outdata << weatherSystem->GetGlobalBaroPressure() << endl;
outdata.close();
}
}

}

static SystemReadyCallback* s_pSystemReadyCallback = nullptr;

extern "C" __declspec(dllexport) void __stdcall DLLStart(__in __notnull IPdk* pPdk)
{
PdkServices::Init(pPdk);
printf("P3d initialized");


s_pSystemReadyCallback = new SystemReadyCallback();

PdkServices::GetEventService()->RegisterCallback(EVENTID_Message, s_pSystemReadyCallback);


}


extern "C" __declspec(dllexport) void __stdcall DLLStop(void)
{
if (s_pSystemReadyCallback != nullptr)
{
s_pSystemReadyCallback = nullptr;
}

PdkServices::Shutdown();
}

My add-on.xml file:

<?xml version="1.0" encoding="utf-8" ?>


- <SimBase.Document Type="AddOnXml" version="4,3" id="add-on">


<AddOn.Name>MyAddOn</AddOn.Name>


<AddOn.Description>My Add-on developed by My Company.</AddOn.Description>


- <AddOn.Component>


<Category>Weather</Category>


<Path>weather</Path>


</AddOn.Component>


- <AddOn.Component>


<Category>DLL</Category>


<Path>C:\Program Files\Lockheed Martin\Prepar3D v4 SDK 4.3.29.25520\PDK\x64\Debug\weather.dll</Path>


<DLLType>PDK</DLLType>


</AddOn.Component>


</SimBase.Document>

Thank you

 

[WarpD]

What do you mean by "on load"?

 

[MerAB]

When the p3d application starts running

 

[WarpD]

You can not read data without a flight being loaded.

 

[Prepar3DGuy]

EVENT_MESSAGE_LOADING_COMPLETE is emitted once when loading of scenario is completed, i.e. you are in a plane on the runway.
I predict that you will find your weatherdata.txt in Prepar3D working directory. (D:\Program Files\Lockheed Martin\Prepar3D v4). By default ofstream create and open files in the relative path to the working directory of applicatoin. By default that is directory where application exe file is located (Prepar3D.exe), not where you have placed your dll.
To write file to the Add-ons folder I use this part of code

std::string logfile_path = "";
LPTSTR userpath = (LPTSTR)malloc(100 * sizeof(TCHAR));
if (GetEnvironmentVariable("USERPROFILE", userpath, 100) != 0)
    logfile_path = std::string(userpath) + "\\Documents\\Prepar3D v4 Add-ons\\YourMagicAddon\\";

outdata.open(logfile_path + "Log.txt");

Or you can look at the DataHarvester in PDK examples. It will search for directory where dll file is located.

P.S. Please formate code in the future posts.

 

[MerAB]

Thank you so much. I found the file there. I will format the code in future

 

[MerAB]

I am facing another difficulty. I am unable to call and use the IWeatherStation interface through the GetWeatherStation function. My code:

if (weatherSystem != NULL)
        {
            P3D::IWeatherStationV430* weatherStation=nullptr;   
            HRESULT station = weatherSystem->GetWeatherStation("GLOB", weatherStation);
            
           P3D::IWeatherStationV430 *weatherStationPointer = *weatherStation;
            outdata.open("weatherdata.txt");
            outdata << "Global Pressure: "<<weatherSystem->GetGlobalBaroPressure() << " millibars" <<endl;
            outdata <<"Global Temp:"<< weatherSystem->GetGlobalTemp() << " degree Celsius" << endl;
            outdata <<"Global Vis Range: "<< weatherSystem->GetGlobalVisRange() << " meters" << endl;
            outdata << "Global Horizontal Wind Speed:"<<weatherSystem->GetGlobalHorizWindSpeed() * 1.94384 << " knots " << endl;
            outdata << "Global wind direction: "<<weatherSystem->GetGlobalWindDirection() << " degrees" << endl;
            outdata << "Global Dew point: "<<weatherSystem->GetGlobalDewPoint() << endl;
            outdata << "Weather Station: " << station << endl;
            outdata << "Cloud layer count:" << weatherStationPointer->GetCloudLayerCount();
            outdata.close();
        }

causes P3d to shutdown on loading, I think the cause is a null pointer exception. How do I access correctly?

 

[Prepar3DGuy]

I think that you are using pointers wrong. Be caution with them in C. I recommend to use smart pointers in C++ and CComPtr for PDK interface classes that implement COM interfacaces.

        CComPtr<IWeatherSystemV430> weatherSystem = PdkServices::GetWeatherSystem();
        if (weatherSystem != NULL)
        {
            CComPtr<IWeatherStationV430> weatherStation;
            HRESULT station = weatherSystem->GetWeatherStation("EHAM", &weatherStation);

            outdata.open("weatherdata.txt");
            outdata << "Global Pressure: " << weatherSystem->GetGlobalBaroPressure() << " millibars" << endl;
            outdata << "Global Temp:" << weatherSystem->GetGlobalTemp() << " degree Celsius" << endl;
            outdata << "Global Vis Range: " << weatherSystem->GetGlobalVisRange() << " meters" << endl;
            outdata << "Global Horizontal Wind Speed:" << weatherSystem->GetGlobalHorizWindSpeed() * 1.94384 << " knots " << endl;
            outdata << "Global wind direction: " << weatherSystem->GetGlobalWindDirection() << " degrees" << endl;
            outdata << "Global Dew point: " << weatherSystem->GetGlobalDewPoint() << endl;
            outdata << "Weather Station: " << station << endl;
            if (SUCCEEDED(station) && weatherStation->IsValid())
                outdata << "Cloud layer count:" << weatherStation->GetCloudLayerCount();
            outdata.close();
        }

Sorry, but I can't test it now.

 

[Prepar3DGuy]

If you are using Visual Studio try to debug you dll's code.
1. Set your project settings to start Prepar3D.exe and working directory accordingly. (See picture).
2. Set breakpoints in your code.
3. Push F5 to start debug.

P3D_SDK is the user Environment Variable I use to simplify switching for new SDK version.

 

[MerAB]

Yes, this code worked.
Thanks a lot