How to do OpenGL live text-rendering for a GUI?

Question

I\'m implementing a GUI built on top of OpenGL. I came to the problem that each GUI will have -- text rendering. I know of several methods of rendering text in OpenGL, howev

Answer 1

could just use these two functions:

void renderstring2d(char string[], float r, float g, float b, float x, float y)
{
    glColor3f(r, g, b);

    glRasterPos2f(x, y);
    for(unsigned int i = 0; i < strlen(string); i++)
        glutBitmapCharacter(GLUT_BITMAP_9_BY_15, string[i]);
}

void renderstring3d(char string[], float r, float g, float b, float x, float y, float z)
{
    glDisable(GL_LIGHTING);
    glColor3f(r, g, b);

    glRasterPos3f(x, y, z);
    for(unsigned int i = 0; i < strlen(string); i++)
        glutBitmapCharacter(GLUT_BITMAP_9_BY_15, string[i]);
}

then when you render 2D text, don't forget to reset both the modelview and projection matrices.

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();

// Render text and quads

glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();

You don't need to render to a quad using these functions, because these functions render directly to the framebuffer.

And if that doesn't work for you, check this out. http://www.opengl.org/resources/faq/technical/fonts.htm

It talks about rendering text using glBitmap, glDrawPixels, and alpha blending.