Engine Fires and Oil Leakage

Over at the Avsim SimConnect Forum, Endre brought up the question of getting engine fires and oil leaks to occur with SimConnect. He said that neither worked properly, so I set out to put together a program to show how it would indeed work as it should.

Problem is, it didn't.

I haven't tried this solution in C++, so it may just be an issue with the managed wrapper. But I think it's more likely that something doesn't work or we aren't implementing it right.

First off, the variables:

ENG ON FIRE:index

On fire state

GENERAL ENG OIL LEAKED PERCENT:index

Percent of max oil capacity leaked

As you can see, ENG ON FIRE is a simple on/off switch for the failure (so it seems) and our oil var is just a percentage of how much oil has been lost. However, our second variable is read-only.

The ever-brilliant Pete Dowson ( http://www.schiratti.com/dowson.html ) has told us that most of the time in that case, we have to find an event that mirrors the effect. So far, I haven't found an event for either of these. Maybe someone has and can point me in the right direction. Because without an event and with the variable non-settable, we won't be able to do anything with it.

So the code is as follows (just for the engine part of things)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

// Include Simconnect and Interop References
// Remember to reference the SDK .DLL in the project
using Microsoft.FlightSimulator.SimConnect;
using System.Runtime.InteropServices;

namespace Engine_Fire
{
   // Standard Windows Form, see the designer for placement
   public partial class Form1 : Form
   {
       // SimConnect Object
       SimConnect simconnect;

       // User-defined win32 event
       const int WM_USER_SIMCONNECT = 0x0402;

       // Data definitions
       enum DEFINITIONS
       {
           EngineData,
       }

       // Requests
       enum DATA_REQUESTS
       {
           SET_ENGINE_FIRE,
       }

       // Our engine data struct.
       // Standard marshalling message
       [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
       struct EngineData
       {
           public bool engine1fire;
           public bool engine2fire;
       };

       // Our initializer
       // To-do: Initialize Simconnect object,
       // Set up data definitions,
       // Add struct to marshaller
       public Form1()
       {
           InitializeComponent();

           // Initialize SimConnect (this is straight from the SDK, just changed the app name)
           simconnect = null;
           try
           {
               simconnect = new SimConnect("Engine Fire Demo", this.Handle, WM_USER_SIMCONNECT, null, 0);
           }
           catch (COMException ex)
           {
               // A connection to the SimConnect server could not be established
               // Normally you would handle the exception here
           }

           // Set up data definitions
           simconnect.AddToDataDefinition(DEFINITIONS.EngineData, "Eng On Fire:0", "bool", SIMCONNECT_DATATYPE.FLOAT32, 0.0f, SimConnect.SIMCONNECT_UNUSED);
           simconnect.AddToDataDefinition(DEFINITIONS.EngineData, "Eng On Fire:1", "bool", SIMCONNECT_DATATYPE.FLOAT32, 0.0f, SimConnect.SIMCONNECT_UNUSED);

           // Add struct to marshaller
           simconnect.RegisterDataDefineStruct(DEFINITIONS.EngineData);

       }

       // Default System Message Handler
       protected override void DefWndProc(ref Message m)
       {
           if (m.Msg == WM_USER_SIMCONNECT)
           {
               if (simconnect != null)
               {
                   simconnect.ReceiveMessage();
               }
           }
           else
           {
               base.DefWndProc(ref m);
           }
       }

       private void button1_Click(object sender, EventArgs e)
       {
           EngineData sendEngFire = new EngineData();

           sendEngFire.engine1fire = true;
           sendEngFire.engine2fire = true;
           simconnect.SetDataOnSimObject(DEFINITIONS.EngineData, SimConnect.SIMCONNECT_OBJECT_ID_USER, SIMCONNECT_DATA_SET_FLAG.DEFAULT, sendEngFire);
       }
   }
}

The key is the button1_Click function. I slapped a button my form and all it's doing is sending a message to FSX to set the ENG ON FIRE vars for engines 1 and 2 to "True". So I fire up FSX, run the code, press the button,

and nothing. No response. I check the console window, and the data certainly is being sent.

Just to make sure something wasn't backwards, I ran a test to pull the variables instead of setting them, and in normal flight, they are set to false, even after trying to set them to "true" with my program.

Here's a shot "in the thick of it" (click for larger version)



Even after sending the variables, they still come back as false.

My assumption right now is that I'm doing it wrong, and I'm certainly open to suggestions.