get witdh of bitmap font problem :/

Hi all…

I want to get the width of a bitmap font character. Ultimately I want to be able to know the width of a string so I can center it when printing.

I use this code from NeHe as a basis:

GLvoid CFonts::glPrintBM(const char *fmt, ...)			// Custom GL "Print" Routine
	char		text[256];								// Holds Our String
	va_list		ap;										// Pointer To List Of Arguments

	if (fmt == NULL)									// If There's No Text
		return;											// Do Nothing

	va_start(ap, fmt);									// Parses The String For Variables
	    vsprintf(text, fmt, ap);						// And Converts Symbols To Actual Numbers
	va_end(ap);											// Results Are Stored In Text

	glPushAttrib(GL_LIST_BIT);							// Pushes The Display List Bits
		glListBase(baseBM - 32);							// Sets The Base Character to 32
		glCallLists(strlen(text), GL_UNSIGNED_BYTE, text);	// Draws The Display List Text
	glPopAttrib();										// Pops The Display List Bits

In another post on this forum I found something useful about GetCharABCWidthsFloat, but I can’t get it to work (I’m pretty new). The compiler says ‘theABCF’ is not initialized and the exe crashes if I run it. If I do theABCF = 0 then I get the same (also a crash).

			int isOK=GetCharABCWidthsFloat(g_OGLwindow.hDC, 'a', 'a', theABCF);
			glRasterPos2f(20.0f, 50.0f);
			g_font.glPrintBM("=%f %f %f", theABCF->abcfA, theABCF->abcfB, theABCF->abcfC);

What should I do to get things running?

Thanks a lot for helping me!

You’re passing a pointer to NULL. Try it with an actual instance of ABCFLOAT.

int isOK=GetCharABCWidthsFloat(g_OGLwindow.hDC, 'a', 'a', &theABCF);

This is more of a general programming/debugging problem than an OpenGL one, for your edification :-).

Make friends with your debugger and the MSDN library, they will help to save you considerable time and anguish.

Hehe…I know I’m sorry to have posted it here. I’ll pay more attention in the future.

Anyway, again, thank you a lot for your advice!