Bottom-left axes as these from Blender

i write opengl program that ables to pick and move 3d objects.
i have problem - i’d like to create small XYZ axes in bottom-left of the screen, like these in blender. they stay in place, when you manipulate camera. i tried with multiple viewports, but i need to show them with transparent background.
do you have any idea?

Just use the same concept to writing a text using OpenGL raster operations. i.e After drawing frame, render the 2D image of axes. I came across a post within the OpenGL coding Beginner section in this forum that talked about similar to your issue. (I am afraid I forgot the exact thread reference number…you may have to look for it).