glPrint Function

Sky · 2003-01-19T21:19:03

I did the bitmap font tutorial thing, but when I compile and run i get a error message that says the memory at 0x000000 cannot be read... I think I need to make ap equal to something, but I''m not sure what... I used some message box things to find out exactly where the error occurs in my code... // --------------------------------------Causes Error GLvoid glPrint(const char *fmt,...) { char text[256]; // holds the string va_list ap; // pointer to list of arguements if (fmt = NULL) return; // between here... va_start(ap, fmt); vsprintf(text, fmt, ap); va_end(ap); // and here, is where the error occurs. glPushAttrib(GL_LIST_BIT); glListBase(base - 32); glCallLists(strlen(text), GL_UNSIGNED_BYTE, text); glPopAttrib(); } // --------------------------------------------------------- // Draw Scene and Text ------------------------------------- int DrawGLScene(GLvoid) { //Drawing Stuff glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //Clear Screen adn Depth Buffer glLoadIdentity(); // Reset Modelview Matrix glTranslatef(0.0f,0.0f,-1.0f); glColor3f(1.0f*float(cos(cnt1)),1.0f*float(sin(cnt2)),1.0f-0.5f*float(cos(cnt1+cnt2))); glRasterPos2f(-0.45f+0.05f*float(cos(cnt1)), 0.35f*float(sin(cnt2))); glPrint("Sky''s Box made with NeHe - %7.2f", cnt1); cnt1+=0.051f; cnt2+=0.005f; return TRUE; } // ---------------------------------------------------------

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Started by Sky January 19, 2003 07:57 AM

10 comments, last by Sky 22 years, 1 month ago

Hawkeye3

122

January 19, 2003 06:03 PM

Arrays are actually just a pointer to an address in memory, in fact, have you ever noticed the glxxv functions? Their arguments say that they accept a pointer, and to use them you pass an array. What you are actually doing is passing a pointer to the array''s starting address.

The moral is that pointers and arrays are more closely related than you think , and that pointers are your friend

Sky

Author

122

January 19, 2003 09:19 PM

Pointers seem dangerous to use and are quite confusing to me. Though it seems they are also quite useful, and if I could just understand them well enough then I could actually use them too. (I just know that after running this and getting the thing saying it can''t read 0x0000000 or whatever than aim started acting funny giving me the same type of error, and then I had to re-install aim..)

glPrint Function

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glPrint Function

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