Moving objects around the screen per pixel using glRasterPos ()

Question

I have the following code for rendering text in my application, first I get the coordinates of the mouse in the world, and then use these coordinates to place my text in the world, so it will follow my mouse position:

Edit: Added buildfont () function in the sample code:

GLvoid BuildFont(GLvoid) // Build Our Bitmap Font { HFONT font; // Windows Font ID HFONT oldfont; // Used For Good House Keeping base = glGenLists(96); // Storage For 96 Characters font = CreateFont( -12, // Height Of Font 0, // Width Of Font 0, // Angle Of Escapement 0, // Orientation Angle FW_NORMAL, // Font Weight FALSE, // Italic FALSE, // Underline FALSE, // Strikeout ANSI_CHARSET, // Character Set Identifier OUT_TT_PRECIS, // Output Precision CLIP_DEFAULT_PRECIS, // Clipping Precision ANTIALIASED_QUALITY, // Output Quality FF_DONTCARE|DEFAULT_PITCH, // Family And Pitch "Verdana"); // Font Name (if not found, its using some other font) oldfont = (HFONT)SelectObject(hDC, font); // Selects The Font We Want wglUseFontBitmaps(hDC, 32, 96, base); // Builds 96 Characters Starting At Character 32 SelectObject(hDC, oldfont); // Selects The Font We Want DeleteObject(font); // Delete The Font } GLvoid glPrint(const char *fmt, ...){ char text[256]; va_list ap; if (fmt == NULL) return; va_start(ap, fmt); vsprintf(text, fmt, ap); va_end(ap); glPushAttrib(GL_LIST_BIT); glListBase(base - 32); glCallLists(strlen(text), GL_UNSIGNED_BYTE, text); glPopAttrib(); } ... glPushMatrix(); glColor4f(0,0,0,1); // X-1 wont work because these are the world coordinates: glRasterPos2d(MousePosX-1, MousePosY); glPrint("TEST"); glColor4f(1,1,0,1); glRasterPos2d(MousePosX, MousePosY); glPrint("TEST"); glPopMatrix(); 

But I want to display multiline texts or texts with "borders" (for example, in the previous code I tried) or text with a background (so that I can distinguish them better from the background) So, how do I do this?

I just need to know how I can move it in pixels, so I could accurately change the position on my screen WITHOUT using a 2-dimensional projection view on top of my 3D rendering ... I just want to make it as simple as possible.

I tried to draw a square under the text, but of course it does not work, since it still uses the coordinates of the world ... so when I rotate the camera, the text does not move along the background of the text ... I'm afraid the only solution is to create another one projection over 3D projection ...

Answer 1

Here is a small piece of code that I use to render debugging text in a small application:

 void renderText(float x, float y, const char* text) { int viewport[4]; glGetIntegerv(GL_VIEWPORT, viewport); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); glOrtho(viewport[0], viewport[2], viewport[1], viewport[3], -1, 1); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glRasterPos2f(x, viewport[3] - y); const int length = (int)strlen(text); for (int i = 0; i < length; ++i) { glutBitmapCharacter(GLUT_BITMAP_9_BY_15, text[i]); } glMatrixMode( GL_PROJECTION ); glPopMatrix(); glMatrixMode( GL_MODELVIEW ); glPopMatrix(); } 

x and y are the desired coordinates of the row window. glutBitmapCharacter(GLUT_BITMAP_9_BY_15, ...) is just a utility function from GLUT that displays a large bitmap symbol measuring 9 x 15 pixels.