MSFS20 Making a (L: local var wrapper

[mariomotta]

#include "ssw_wasm_gauges.h"
#include "simvars.h"
PCSTRINGZ custom_event_name = "custom_event";
PCSTRINGZ dummy_name = "dummy";

struct SSWGaugeCustomVar
{
    ID custom_event;
    ID dummy;
};

SSWGaugeCustomVar m_SSWGaugeCustomVars;
LocalSimVar* custom_event = (LocalSimVar*) NULL;

////////////////////////////////////////////////
extern "C" {
  
    MSFS_CALLBACK bool custom_event_gauge_callback(FsContext ctx, int service_id, void* pData)
    {
        switch (service_id)
        {
        case PANEL_SERVICE_PRE_INSTALL:
        {

            if (custom_event == (LocalSimVar*) NULL )
                custom_event = new LocalSimVar(custom_event_name);
            return true;
        }
        break;
        case PANEL_SERVICE_POST_INSTALL:
.......

Hello,
above code is an attempt to make a wrapper for local vars, however it seems the calling a C++ ctor has problems with linking:

C:\MSFS SDK\WASM\vs\2019\Microsoft.Cpp.MSFS.Common.targets(473, 5) error MSB4181: The "MSFSLinkTask" task returned false but did not log an error.

someone had same issue ?
TIA
mario

 

[Prepar3DGuy]

I have never seen this error.
What do you mean of wrapper for local vars? What does LocalSimVar class do? And where is it implemented?

 

[mariomotta]

Thanks for answer.
btw: using your code exaple above i could find the "rosebud" to make C++ gauges.

I mean a "wrapper" an object that encapsulates some behaviours of sim vars.
LocalSimVar is a class into below header file (own made), a wrapper for named variables in MSFS
/Mario

// simvars.h
#pragma once
#include "ssw_wasm_gauges.h"
/*
Generic simulation var, root class
*/
class SimVar {
protected:
    STRING name[128];
    ENUM var_units;
    ENUM var_enum;
public:
    SimVar(PCSTRINGZ s_name): var_units(0),var_enum(0) { strcpy(name, s_name); }
    ~SimVar() {}
    virtual void Set(FLOAT64 val) {}
    virtual double Get(void) { return 0.0; }
    virtual void operator=(FLOAT64 value) {}
    virtual FLOAT operator*() { return 0.0; }
    virtual bool operator==(FLOAT64 value) { return false; }
};
/*
* Read Only simulation var: A:, P: ...
*/

class ROSimVar : public SimVar {
protected:
    SINT32 index;
public:
    ROSimVar(PCSTRINGZ s_name, char* type, SINT32 index = 0);
    ~ROSimVar() {}
    double Get(void);
};
/*
* Local simulation var : L:
*/

class LocalSimVar : public SimVar {
    ID id;
public:
    LocalSimVar(PCSTRINGZ s_name);
    ~LocalSimVar();
    double Get(void);
    void Set(FLOAT64 val);
};

and the implementation here:

#include "simvars.h"
/*
*/
ROSimVar::ROSimVar(PCSTRINGZ s_name, char* type,SINT32 index):SimVar(name),index(index) {
    var_units = get_aircraft_var_enum(type);
    var_enum = get_aircraft_var_enum(s_name);
}
/*
*/
double ROSimVar::Get(void) {
    return aircraft_varget(var_enum, var_units, index);
}
/*
*/
LocalSimVar::LocalSimVar(PCSTRINGZ s_name) : SimVar(s_name) {
    ID m_id = check_named_variable(s_name);
    if(m_id == -1)
        id = register_named_variable(s_name);
    else
        id = m_id;
}

 

[Prepar3DGuy]

I have reproduced your error.
The problem was that you doesn't implement methods Get and Set of class LocalSimVar.

class LocalSimVar : public SimVar {
    ID id;
public:
    LocalSimVar(PCSTRINGZ s_name);
    ~LocalSimVar() {};
    double Get(void) { return get_named_variable_value(id); };
    void Set(FLOAT64 val) { set_named_variable_value(id, val); };
};

P.S. also show warning on parent constructor call with wrong parameter
ROSimVar::ROSimVar(PCSTRINGZ s_name, char* type, SINT32 index) :SimVar(s_name), index(index) {
P.S.2 you class architecture is not good. Because you inherited from SimVar class that already have Set, operator= and so on methods you confuse the user of ROSimVar class.

 

[mariomotta]

I have reproduced your error.
The problem was that you doesn't implement methods Get and Set of class LocalSimVar.

class LocalSimVar : public SimVar {
    ID id;
public:
    LocalSimVar(PCSTRINGZ s_name);
    ~LocalSimVar() {};
    double Get(void) { return get_named_variable_value(id); };
    void Set(FLOAT64 val) { set_named_variable_value(id, val); };
};

P.S. also show warning on parent constructor call with wrong parameter
ROSimVar::ROSimVar(PCSTRINGZ s_name, char* type, SINT32 index) :SimVar(s_name), index(index) {
P.S.2 you class architecture is not good. Because you inherited from SimVar class that already have Set, operator= and so on methods you confuse the user of ROSimVar class.

Thanks for answer, completely right, forgotten to implement the LocalSimVar method already declared.
However cannot agree completely:
- inheritance assures that the right method will be called on the right object, the ROSimVar::Get() will be called on ROSimVar object while SimVar::Get() method will be called on the SimVar objects., furthermore the virtuality assures that having a generic SimVar* the ambiguity will be resolved and the right method will be called on the right object.
However again thanks, often trivial errors can't be seen.

 

[WarpD]

You didn't use the override moniker on the methods declared in the descendent classes, the only way to truly ensure that the correct method is called.

 

[Firecracker2020]

I have been working with MSFS wasm projects and development. I have not been able to successfully do a set on anything in the sim yet from my cpp wasm module. Have you guys been able to set anything successfully yet through a wasm module? wing lights on/off etc?

I have tried -
lookup_var( &nav_light);
trigger_key_event( KEY_TOGGLE_NAV_LIGHTS, 0 );

i have also tried-
set_named_variable_value - after I got the ID


Are these not wired up to the API yet or is my GaugePlane not "Virtually wired up correctly"?

 

[Prepar3DGuy]

Firecracker2020, try this.
Light from SDK sample GaugePlane responds accordingly.

send_key_event(KEY_TOGGLE_NAV_LIGHTS, 0);

 

[WarpD]

The difference between trigger_key_event and send_key_event is the same as a windows PostMessage versus SendMessage. Other than that, they should work identical.

 

[Prepar3DGuy]

Other than that, they should work identical.

I also expected that. But in my example...

    case PANEL_SERVICE_PRE_UPDATE:
    {
        // Logic to toggle lights
        if ((g_Time - g_prevChangeTime) > 2)
        {
            g_prevChangeTime = g_Time;
            //trigger_key_event(KEY_TOGGLE_NAV_LIGHTS, 0); // doesn't work
            send_key_event(KEY_TOGGLE_NAV_LIGHTS, 0);
        }
        return true;
    }

 

[Firecracker2020]

I also expected that. But in my example...

    case PANEL_SERVICE_PRE_UPDATE:
    {
        // Logic to toggle lights
        if ((g_Time - g_prevChangeTime) > 2)
        {
            g_prevChangeTime = g_Time;
            //trigger_key_event(KEY_TOGGLE_NAV_LIGHTS, 0); // doesn't work
            send_key_event(KEY_TOGGLE_NAV_LIGHTS, 0);
        }
        return true;
    }

 

[Firecracker2020]

OMG It worked!!!!!!!!!!!!, You would not believe how much that helped me. I have tried and tried all ways. Now I am on my way. I owe you my friend.

 

[WarpD]

If trigger_key_event isn't working... it needs to be reported.