I call a custom function like this to put a string on the screen:
// Debug: draw a blue line
glColor3f((GLfloat)0, (GLfloat)0, (GLfloat)1);
glBegin(GL_LINES);
glVertex2i(1, 1);
glVertex2i(1, 10);
glEnd();
// Call text renderer.
write_default_bitmap_text((const unsigned char*)"TEST string 1", 100, 100);
write_default_bitmap_text((const unsigned char*)"TEST string 2", 100, 120);
and this is the custom function:
void write_default_bitmap_text(const unsigned char* text,
const int x,
const int y,
const font_x_align x_align)
{
if (x_align == font_x_align::Left) {
glRasterPos2i(x, y);
}
else if (x_align == font_x_align::Center) {
glRasterPos2i(x - glutBitmapLength(default_font, text)/2, y);
}
else {
glRasterPos2i(x - glutBitmapLength(default_font, text), y);
}
glColor3f((GLfloat)1, (GLfloat)0, (GLfloat)0); //XXX debug
glDisable(GL_TEXTURE_2D); //XXX debug
glDisable(GL_LIGHTING); //XXX debug
glutBitmapString(default_font, text);
next_call_font_color = default_font_color;
}
where I hardcoded the text color to be red for debugging. To my surprise I see that the first string uses the blue color for the line just before calling write_default_bitmap_text()
, but not red, and only the second string becomes red as intended.
If I place the few lines above for drawing the blue line inside my write_default_bitmap_text()
body, then the text does not use the blue color but whatever was used for line drawing before calling write_default_bitmap_text()
for the first time.
I have absolutely no idea what happens here.
glRasterPos*()
"locks in" the current color/texure-coordinate state (much like glVertex*()
does) while setting the raster position, so calling glColor*()
after it will only affect the next glRasterPos*()
call.