SDK Question Displaying the equatorial coordinates on HUD

[fg2000]

Hello everyone! I'm currently working on a slightly customized HUD for a personal 3D model showcasing project, and among other things I'd like to include information such as the equatorial position over a given planet/moon on the HUD, but I haven't managed to do that yet. By digging through the included samples I managed to implement things like altitude and pitch/bank/yaw but whenever I try to use the GetFocusEquPos function in an identical fashion, I end up with an identifier not found error. Can someone provide me with directions or better yet a sample which includes the usage of this function either in HUD or as an annotation, as I am obviously a complete noob in C++ (and programming in general). Thank you!

 

[kuddel]

Could you post the code that isn't working (+- a few code lines above and below, so one can get the context)?

I have never used GetFocusEquPos, but it should behave equal to this code (using a object-handle that is obtained by oapiGetFocusObject in the example below):

OBJHANDLE hObj;
double lng, lat, rad;

hObj = oapiGetFocusObject();
if (oapiGetEquPos(hObj, &lng, &lat, &rad)) {
  // lng, lat and rad should contain valid values...
}

The sample above only uses the OAPI calls. When you work with a VESSEL Object, the parameters are references, not pointers (so no ampersand in from of the parameters), so it looks lore like this:

double lng, lat, rad;
// In case we have a pointer to a VESSEL Object:
if (NULL != pVessel->GetEquPos(lng, lat, rad)) {
  // lng, lat and rad should contain valid values...
}
// In case we have a VESSEL Object (or reference):
if (NULL != pVessel.GetEquPos(lng, lat, rad)) {
  // lng, lat and rad should contain valid values...
}

Anyhow, I think it would be best to show some of your code, so we are on the same page.

 

[fg2000]

Thank you for the response! I'm using the ShuttlePB as a base to develop the HUD since it's a very basic vessel, and in this example I managed to display Pitch information in degrees, but whenever I try to use the same setup to display the coordinates either with oapiGetEquPos or oapiGetFocusEquPos I end up with an error. I included the entire code just in case, but I highligted in red my additions.

// ==============================================================
//                 ORBITER MODULE: ShuttlePB
//                  Part of the ORBITER SDK
//          Copyright (C) 2002-2004 Martin Schweiger
//                   All rights reserved
//
// ShuttlePB.cpp
// Control module for ShuttlePB vessel class
//
// Notes:
// This is an example for a "minimal" vessel implementation which
// only overloads the clbkSetClassCaps method to define vessel
// capabilities and otherwise uses the default VESSEL class
// behaviour.
// ==============================================================

#define STRICT
#define ORBITER_MODULE

#include "orbitersdk.h"

// ==============================================================
// Some vessel parameters
// ==============================================================
const double  PB_SIZE       = 3.5;             // mean radius [m]
const VECTOR3 PB_CS         = {10.5,15.0,5.8}; // x,y,z cross sections [m^2]
const VECTOR3 PB_PMI        = {2.28,2.31,0.79};// principal moments of inertia (mass-normalised) [m^2]
const VECTOR3 PB_RD         = {0.025,0.025,0.02};//{0.05,0.1,0.05};  // rotation drag coefficients
const double  PB_EMPTYMASS  = 500.0;           // empty vessel mass [kg]
const double  PB_FUELMASS   = 750.0;           // max fuel mass [kg]
const double  PB_ISP        = 5e4;             // fuel-specific impulse [m/s]
const VECTOR3 PB_COP        = {0,0,0};//{0,0,-0.1};      // centre of pressure for airfoils [m]
const double  PB_VLIFT_C    = 2.0;             // chord length [m]
const double  PB_VLIFT_S    = 2.0;             // wing area [m^2]
const double  PB_VLIFT_A    = 2.5;             // wing aspect ratio
const double  PB_HLIFT_C    = 2.0;             // chord length [m]
const double  PB_HLIFT_S    = 1.5;             // wing area [m^2]
const double  PB_HLIFT_A    = 2.0;             // wing aspect ratio

const double  PB_MAXMAINTH  = 3e4;             
const double  PB_MAXHOVERTH = 1.5e4;
const double  PB_MAXRCSTH   = 2e2;

const VECTOR3 PB_DOCK_POS   = {0,1.3,-1};      // docking port location [m]
const VECTOR3 PB_DOCK_DIR   = {0,1,0};         // docking port approach direction
const VECTOR3 PB_DOCK_ROT   = {0,0,-1};        // docking port alignment direction

[COLOR="Red"]double Pitch;[/COLOR]

// Define impact convex hull
static const DWORD ntdvtx = 12;
static TOUCHDOWNVTX tdvtx[ntdvtx] = {
	{_V( 0,  -1.5, 2  ), 2e4, 1e3, 1.6, 1},
	{_V(-1,  -1.5,-1.5), 2e4, 1e3, 3.0, 1},
	{_V( 1,  -1.5,-1.5), 2e4, 1e3, 3.0, 1},
	{_V(-0.5,-0.75,3  ), 2e4, 1e3, 3.0},
	{_V( 0.5,-0.75,3  ), 2e4, 1e3, 3.0},
	{_V(-2.6,-1.1,-1.9), 2e4, 1e3, 3.0},
	{_V( 2.6,-1.1,-1.9), 2e4, 1e3, 3.0},
	{_V(-1,   1.3, 0  ), 2e4, 1e3, 3.0},
	{_V( 1,   1.3, 0  ), 2e4, 1e3, 3.0},
	{_V(-1,   1.3,-2  ), 2e4, 1e3, 3.0},
	{_V( 1,   1.3,-2  ), 2e4, 1e3, 3.0},
	{_V( 0,   0.3,-3.8), 2e4, 1e3, 3.0}
};

[COLOR="Red"]oapi::Font *m_pHudNormalFont;
int fontSize = 20;[/COLOR]

// Calculate lift coefficient [Cl] as a function of aoa (angle of attack) over -Pi ... Pi
// Implemented here as a piecewise linear function
double LiftCoeff (double aoa)
{
	int i;
	const int nlift = 9;
	static const double AOA[nlift] = {-180*RAD,-60*RAD,-30*RAD,-1*RAD,15*RAD,20*RAD,25*RAD,60*RAD,180*RAD};
	static const double CL[nlift]  = {       0,      0,   -0.1,     0,   0.2,  0.25,   0.2,     0,      0};
	static const double SCL[nlift] = {(CL[1]-CL[0])/(AOA[1]-AOA[0]), (CL[2]-CL[1])/(AOA[2]-AOA[1]),
		                              (CL[3]-CL[2])/(AOA[3]-AOA[2]), (CL[4]-CL[3])/(AOA[4]-AOA[3]),
									  (CL[5]-CL[4])/(AOA[5]-AOA[4]), (CL[6]-CL[5])/(AOA[6]-AOA[5]),
									  (CL[7]-CL[6])/(AOA[7]-AOA[6]), (CL[8]-CL[7])/(AOA[8]-AOA[7])};
	for (i = 0; i < nlift-1 && AOA[i+1] < aoa; i++);
	return CL[i] + (aoa-AOA[i])*SCL[i];
}

// ==============================================================
// Shuttle-PB class interface
// ==============================================================

class ShuttlePB: public VESSEL3 {
public:
	ShuttlePB (OBJHANDLE hVessel, int flightmodel);
	~ShuttlePB ();
	void clbkSetClassCaps (FILEHANDLE cfg);
	[COLOR="Red"]void clbkPreStep (double simt, double simdt, double mjd);
	bool clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, oapi::Sketchpad *skp);[/COLOR]

private:
	static void vlift (VESSEL *v, double aoa, double M, double Re,
		void *context, double *cl, double *cm, double *cd);
	static void hlift (VESSEL *v, double aoa, double M, double Re,
		void *context, double *cl, double *cm, double *cd);

	// transformations for control surface animations
	static MGROUP_ROTATE trans_Laileron, trans_Raileron;
	static MGROUP_ROTATE trans_Lelevator, trans_Relevator;
};

ShuttlePB::ShuttlePB (OBJHANDLE hVessel, int flightmodel)
: VESSEL3 (hVessel, flightmodel)
{
}

ShuttlePB::~ShuttlePB ()
{
}

// animation transformation definitions
static UINT GRP_LWING = 2;
static UINT GRP_RWING = 3;
static VECTOR3 LWING_REF  = {-1.3,-0.725,-1.5};
static VECTOR3 LWING_AXIS = {-0.9619,-0.2735,0};
static VECTOR3 RWING_REF  = {1.3,-0.725,-1.5};
static VECTOR3 RWING_AXIS = {0.9619,-0.2735,0};
static float AILERON_RANGE = (float)(20.0*RAD);
static float ELEVATOR_RANGE = (float)(30.0*RAD);
MGROUP_ROTATE ShuttlePB::trans_Laileron (0, &GRP_LWING, 1, LWING_REF, LWING_AXIS, AILERON_RANGE);
MGROUP_ROTATE ShuttlePB::trans_Raileron (0, &GRP_RWING, 1, RWING_REF, RWING_AXIS, AILERON_RANGE);
MGROUP_ROTATE ShuttlePB::trans_Lelevator (0, &GRP_LWING, 1, LWING_REF, LWING_AXIS, -ELEVATOR_RANGE);
MGROUP_ROTATE ShuttlePB::trans_Relevator (0, &GRP_RWING, 1, RWING_REF, RWING_AXIS, ELEVATOR_RANGE);


// ==============================================================
// Overloaded callback functions
// ==============================================================

// --------------------------------------------------------------
// Set the capabilities of the vessel class
// --------------------------------------------------------------
void ShuttlePB::clbkSetClassCaps (FILEHANDLE cfg)
{
	THRUSTER_HANDLE th_main, th_hover, th_rcs[14], th_group[4];

	// physical vessel parameters
	SetSize (PB_SIZE);
	SetEmptyMass (PB_EMPTYMASS);
	SetPMI (PB_PMI);
	SetCrossSections (PB_CS);
	SetRotDrag (PB_RD);
	SetTouchdownPoints (tdvtx, ntdvtx);

	// docking port definitions
	SetDockParams (PB_DOCK_POS, PB_DOCK_DIR, PB_DOCK_ROT);

	// airfoil definitions
	CreateAirfoil3 (LIFT_VERTICAL,   PB_COP, vlift, NULL, PB_VLIFT_C, PB_VLIFT_S, PB_VLIFT_A);
	CreateAirfoil3 (LIFT_HORIZONTAL, PB_COP, hlift, NULL, PB_HLIFT_C, PB_HLIFT_S, PB_HLIFT_A);

	// control surface animations
	UINT anim_Laileron = CreateAnimation (0.5);
	UINT anim_Raileron = CreateAnimation (0.5);
	UINT anim_elevator = CreateAnimation (0.5);
	AddAnimationComponent (anim_Laileron, 0, 1, &trans_Laileron);
	AddAnimationComponent (anim_Raileron, 0, 1, &trans_Raileron);
	AddAnimationComponent (anim_elevator, 0, 1, &trans_Lelevator);
	AddAnimationComponent (anim_elevator, 0, 1, &trans_Relevator);

	// aerodynamic control surface defintions
	CreateControlSurface (AIRCTRL_ELEVATOR, 1.5, 0.7, _V( 0,0,-2.5), AIRCTRL_AXIS_XPOS, anim_elevator);
	CreateControlSurface (AIRCTRL_AILERON, 1.5, 0.25, _V( 1,0,-2.5), AIRCTRL_AXIS_XPOS, anim_Laileron);
	CreateControlSurface (AIRCTRL_AILERON, 1.5, 0.25, _V(-1,0,-2.5), AIRCTRL_AXIS_XNEG, anim_Raileron);

	// propellant resources
	PROPELLANT_HANDLE hpr = CreatePropellantResource (PB_FUELMASS);

	// main engine
	th_main = CreateThruster (_V(0,0,-4.35), _V(0,0,1), PB_MAXMAINTH, hpr, PB_ISP);
	CreateThrusterGroup (&th_main, 1, THGROUP_MAIN);
	AddExhaust (th_main, 8, 1, _V(0,0.3,-4.35), _V(0,0,-1));

	PARTICLESTREAMSPEC contrail_main = {
		0, 5.0, 16, 200, 0.15, 1.0, 5, 3.0, PARTICLESTREAMSPEC::DIFFUSE,
		PARTICLESTREAMSPEC::LVL_PSQRT, 0, 2,
		PARTICLESTREAMSPEC::ATM_PLOG, 1e-4, 1
	};
	PARTICLESTREAMSPEC exhaust_main = {
		0, 2.0, 20, 200, 0.05, 0.1, 8, 1.0, PARTICLESTREAMSPEC::EMISSIVE,
		PARTICLESTREAMSPEC::LVL_SQRT, 0, 1,
		PARTICLESTREAMSPEC::ATM_PLOG, 1e-5, 0.1
	};
	AddExhaustStream (th_main, _V(0,0.3,-10), &contrail_main);
	AddExhaustStream (th_main, _V(0,0.3,-5), &exhaust_main);

	// hover engine
	th_hover = CreateThruster (_V(0,-1.5,0), _V(0,1,0), PB_MAXHOVERTH, hpr, PB_ISP);
	CreateThrusterGroup (&th_hover, 1, THGROUP_HOVER);
	AddExhaust (th_hover, 8, 1, _V(0,-1.5,1), _V(0,-1,0));
	AddExhaust (th_hover, 8, 1, _V(0,-1.5,-1), _V(0,-1,0));

	PARTICLESTREAMSPEC contrail_hover = {
		0, 5.0, 8, 200, 0.15, 1.0, 5, 3.0, PARTICLESTREAMSPEC::DIFFUSE,
		PARTICLESTREAMSPEC::LVL_PSQRT, 0, 2,
		PARTICLESTREAMSPEC::ATM_PLOG, 1e-4, 1
	};
	PARTICLESTREAMSPEC exhaust_hover = {
		0, 2.0, 10, 200, 0.05, 0.05, 8, 1.0, PARTICLESTREAMSPEC::EMISSIVE,
		PARTICLESTREAMSPEC::LVL_SQRT, 0, 1,
		PARTICLESTREAMSPEC::ATM_PLOG, 1e-5, 0.1
	};

	AddExhaustStream (th_hover, _V(0,-3, 1), &contrail_hover);
	AddExhaustStream (th_hover, _V(0,-3,-1), &contrail_hover);
	AddExhaustStream (th_hover, _V(0,-2, 1), &exhaust_hover);
	AddExhaustStream (th_hover, _V(0,-2,-1), &exhaust_hover);

	// RCS engines
	th_rcs[ 0] = CreateThruster (_V( 1,0, 3), _V(0, 1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 1] = CreateThruster (_V( 1,0, 3), _V(0,-1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 2] = CreateThruster (_V(-1,0, 3), _V(0, 1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 3] = CreateThruster (_V(-1,0, 3), _V(0,-1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 4] = CreateThruster (_V( 1,0,-3), _V(0, 1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 5] = CreateThruster (_V( 1,0,-3), _V(0,-1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 6] = CreateThruster (_V(-1,0,-3), _V(0, 1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 7] = CreateThruster (_V(-1,0,-3), _V(0,-1,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 8] = CreateThruster (_V( 1,0, 3), _V(-1,0,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[ 9] = CreateThruster (_V(-1,0, 3), _V( 1,0,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[10] = CreateThruster (_V( 1,0,-3), _V(-1,0,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[11] = CreateThruster (_V(-1,0,-3), _V( 1,0,0), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[12] = CreateThruster (_V( 0,0,-3), _V(0,0, 1), PB_MAXRCSTH, hpr, PB_ISP);
	th_rcs[13] = CreateThruster (_V( 0,0, 3), _V(0,0,-1), PB_MAXRCSTH, hpr, PB_ISP);

	th_group[0] = th_rcs[0];
	th_group[1] = th_rcs[2];
	th_group[2] = th_rcs[5];
	th_group[3] = th_rcs[7];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_PITCHUP);

	th_group[0] = th_rcs[1];
	th_group[1] = th_rcs[3];
	th_group[2] = th_rcs[4];
	th_group[3] = th_rcs[6];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_PITCHDOWN);

	th_group[0] = th_rcs[0];
	th_group[1] = th_rcs[4];
	th_group[2] = th_rcs[3];
	th_group[3] = th_rcs[7];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_BANKLEFT);

	th_group[0] = th_rcs[1];
	th_group[1] = th_rcs[5];
	th_group[2] = th_rcs[2];
	th_group[3] = th_rcs[6];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_BANKRIGHT);

	th_group[0] = th_rcs[0];
	th_group[1] = th_rcs[4];
	th_group[2] = th_rcs[2];
	th_group[3] = th_rcs[6];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_UP);

	th_group[0] = th_rcs[1];
	th_group[1] = th_rcs[5];
	th_group[2] = th_rcs[3];
	th_group[3] = th_rcs[7];
	CreateThrusterGroup (th_group, 4, THGROUP_ATT_DOWN);

	th_group[0] = th_rcs[8];
	th_group[1] = th_rcs[11];
	CreateThrusterGroup (th_group, 2, THGROUP_ATT_YAWLEFT);

	th_group[0] = th_rcs[9];
	th_group[1] = th_rcs[10];
	CreateThrusterGroup (th_group, 2, THGROUP_ATT_YAWRIGHT);

	th_group[0] = th_rcs[8];
	th_group[1] = th_rcs[10];
	CreateThrusterGroup (th_group, 2, THGROUP_ATT_LEFT);

	th_group[0] = th_rcs[9];
	th_group[1] = th_rcs[11];
	CreateThrusterGroup (th_group, 2, THGROUP_ATT_RIGHT);

	CreateThrusterGroup (th_rcs+12, 1, THGROUP_ATT_FORWARD);
	CreateThrusterGroup (th_rcs+13, 1, THGROUP_ATT_BACK);

	// camera parameters
	SetCameraOffset (_V(0,0.8,0));

	// associate a mesh for the visual
	AddMesh ("ShuttlePB");
}

// ==============================================================
// Airfoil lift/drag functions
// ==============================================================

void ShuttlePB::vlift (VESSEL *v, double aoa, double M, double Re,
	void *context, double *cl, double *cm, double *cd)
{
	static const double clp[] = {  // lift coefficient from -pi to pi in 10deg steps
		-0.1,-0.5,-0.4,-0.1,0,0,0,0,0,0,0,0,0,0,-0.2,-0.6,-0.6,-0.4,0.2,0.5,0.9,0.8,0.2,0,0,0,0,0,0,0,0,0,0.1,0.4,0.5,0.3,-0.1,-0.5
	};
	static const double aoa_step = 10.0*RAD;
	double a, fidx, saoa = sin(aoa);
	a = modf((aoa+PI)/aoa_step, &fidx);
	int idx = (int)(fidx+0.5);
	*cl = clp[idx]*(1.0-a) + clp[idx+1]*a;     // linear interpolation
	*cm = 0.0; //-0.03*sin(aoa-0.1);
	*cd = 0.03 + 0.4*saoa*saoa;                // profile drag
	*cd += oapiGetInducedDrag (*cl, 1.0, 0.5); // induced drag
	*cd += oapiGetWaveDrag (M, 0.75, 1.0, 1.1, 0.04);  // wave drag
}

void ShuttlePB::hlift (VESSEL *v, double aoa, double M, double Re,
	void *context, double *cl, double *cm, double *cd)
{
	static const double clp[] = {  // lift coefficient from -pi to pi in 45deg steps
		0,0.4,0,-0.4,0,0.4,0,-0.4,0,0.4
	};
	static const double aoa_step = 45.0*RAD;
	double a, fidx;
	a = modf((aoa+PI)/aoa_step, &fidx);
	int idx = (int)(fidx+0.5);
	*cl = clp[idx]*(1.0-a) + clp[idx+1]*a;     // linear interpolation
	*cm = 0.0;
	*cd = 0.03;
	*cd += oapiGetInducedDrag (*cl, 1.5, 0.6); // induced drag
	*cd += oapiGetWaveDrag (M, 0.75, 1.0, 1.1, 0.04);  // wave drag
}

[COLOR="Red"]// ==============================================================
// Custom HUD test - reference : https://www.orbiter-forum.com/showthread.php?t=39533
// ==============================================================
void ShuttlePB::clbkPreStep (double simt, double simdt, double mjd)
{
	Pitch = GetPitch() * 57.2958;
}

bool ShuttlePB::clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, oapi::Sketchpad *skp)
{
	oapi::Font *pOrgHUDFont = skp->SetFont(m_pHudNormalFont);

	VESSEL3::clbkDrawHUD(mode, hps, skp);

	DWORD x_coord = 480;
	DWORD y_coord = 540;

	{
		skp->SetTextColor(0x00FFFFFF);
		char abuf[256];
		sprintf(abuf, "Pitch %0.0f", Pitch);
		skp->Text(x_coord, y_coord + 0, abuf, strlen(abuf));
	}

	skp->SetFont(pOrgHUDFont);

	return true;
}
[/COLOR]
// --------------------------------------------------------------
// Vessel initialisation
// --------------------------------------------------------------
DLLCLBK VESSEL *ovcInit (OBJHANDLE hvessel, int flightmodel)
{
	return new ShuttlePB (hvessel, flightmodel);
}

// --------------------------------------------------------------
// Vessel cleanup
// --------------------------------------------------------------
DLLCLBK void ovcExit (VESSEL *vessel)
{
	if (vessel) delete (ShuttlePB*)vessel;
}

 

[kuddel]

Thanks for the code.
I haven't looked very deep into it, but are you sure you need to get the values at the PreStep callback? I would rather take the PostStep callback, but that might not be a problem here (as I have not yet looked very deep into it).
But what I can imagine is, that some data is not (yet fully) available at the very first PreStep callback, so you might try to ignore/skip erroneous GetEquPos() nd see if they return O.K. some (Sim-)timesteps later.

I'll take a closer look at your approach when I find some time.
Please be patient (and try out more)

---------- Post added at 23:46 ---------- Previous post was at 22:41 ----------

Hi I got the code working.
What I had to change was basically:

• Removed the font-backup and -restore things.
• Set the text-color to a fitting BBGGRR format.

That's basically it. The calls to GetEquPos() worked fine out of the box. (I just added some debugging helping members, ass I expected some failures )

Ah and by the way I was using Orbiter BETA (r90). I didn't check if it works with Orbiter 2016, though.

class ShuttlePB: public VESSEL3 {
	// ...
	int    m_Err;   // Error count
	bool   m_Valid; // Just a debug flag, indicating Lat, Lon & Rad are valid
	double m_Lat;
	double m_Lon;
	double m_Rad;
};

ShuttlePB::ShuttlePB (OBJHANDLE hVessel, int flightmodel)
: VESSEL3 (hVessel, flightmodel)
	, m_Err()
	, m_Lat()
	, m_Lon()
	, m_Rad()
	, m_Valid(false)
{
}

// [...]

// ==============================================================
// Custom HUD test
// ==============================================================

void ShuttlePB::ShuttlePB::clbkPreStep(double simt, double simdt, double mjd)
{
	auto result = GetEquPos(m_Lon, m_Lat, m_Rad);
	if (result == NULL) {
		m_Valid = true;
		m_Err++;
	}
	else {
		m_Valid = true;
	}
}

bool ShuttlePB::clbkDrawHUD(int mode, const HUDPAINTSPEC *hps, oapi::Sketchpad *skp)
{
	VESSEL3::clbkDrawHUD(mode, hps, skp);

	DWORD x_coord = hps->W / 4; // Some "middle"ish...
	DWORD y_coord = hps->H / 2; // ...position

	if (m_Valid)
	{
		skp->SetTextColor(0x0000FF);
		char abuf[256];
		sprintf(abuf, "Lat: %0.3f, Lon: %0.3f, Rad: %f", m_Lat, m_Lon, m_Rad);
		auto res = skp->Text(x_coord, y_coord, abuf, strlen(abuf));
		if (!res) {
			m_Err++;
		}
	}

	return true;
}

 

[martins]

Kuddel has already addressed the compilation error issue, but I wanted to highlight an additional problem with your original code:

The "Pitch" variable is set and used by each individual instance of the vessel class but it is declared as a global (i.e. shared) variable. Since the clbkPreStep function is called for all vessel instances before the clbkDrawHUD function is called for any of them, it means that each instance overwrites the value of the previous instance, and only the value set by the last instance survives to be read out by the clbkDrawHUD function for any instance that uses it. So if your scenario contains more than one instance of your vessel class, then the HUD readout will be wrong for all but the last instance.

The solution to this problem is to make the Pitch variable individual to each vessel instance, by making it a (non-static) member of the class.

When testing and debugging a new vessel class, it is always a good idea to try a scenario with multiple instances of the new class, to catch problems of this kind. Also make sure to use the scenario editor to create and delete instances of the new vessel during the simulation, to catch problems during construction and destruction.

You may already know all that, and the code sample is just a quick and dirty debugging hack, in which case excuse the lengthy blurb above. It may still be helpful for other coders.

Btw. I am not sure why setting and resetting the HUD font should cause problems here. However, I didn't see the m_pHudNormalFont pointer being defined in the code. So unless this was just missed out when pasting the code, it might be the reason. Also, resetting the font before calling the default clbkDrawHUD function could lead to undesired side effects, if the default function expects a specific font, or if it resets the font itself.