Moving objects on screen by per pixel basis with glRasterPos() - c++

Question

I have the following code to render text in my app, first i get the mouse coordinates in the world, then use those coordinates to place my text in the world, so it will follow my mouse position:
Edit: added buildfont() function in code example:
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 render multiline texts, or texts with "borders" (like in above code i tried) or text with background (so i could distinguish them better from the background)
So how i do this?
I just need to know how i can move it in pixels, so i could precisely modify the position on my screen WITHOUT using 2d projection view on top of my 3d render projection... i just want to make it as simple as possible.
I tried to draw a quad under the text, but of course it doesnt work since its still using the world coordinates... so when i rotate my camera the text doesnt move along the background of the text... i am afraid the only solution is to create another projection on top of the 3d projection...

Answer 1

Here's a small snippet of code that I use to render some debug 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();
}
xand y is the desired window coordinates of the string. glutBitmapCharacter(GLUT_BITMAP_9_BY_15, ...) is just a utility function from GLUT that renders a 9 x 15 pixels large bitmap character.