Aye, I''ve started with OpenGL a few weeks ago, and I''m coming quite far at the moment. There is one thing though I cannot find in my book or any tutorials I''ve read. This is the making of a GUI. What I want to make is basically a partially-transparent GUI with knobs and buttons which the user can use to control the 3D world and display data in a 2D way. If you don''t know what I exactly mean think of the health/ammo information given in first person shooters, like the HUD in Unreal. Any basic tips/tutorials are very welcome. Please don''t describe it too cryptic as I''m still not fully used to the OpenGL API. Thank you

Here is one solution.. I think there are better, but this is one way to do it.


// Enter Ortho Mode: (Render infront of the camera... kind of)
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho( left, right, bottom, top, 0, 1); // 0/1 is near/far
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

// Enable Blending, so that you can render transparent things..
glBlendFunc(GL_SCR_ALPHA,GL_ONE);
glEnable(GL_BLEND);

// Just render anything here =) (like quads with textures)

glDisable(GL_BLEND);

// Back To Perspective:
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);

Here''s the first of an excellent series of articles dealing with the creation of a GUI. The articles are DirectX based, but the theory is the same - as the previous poster pointed out, actually rendering the GUI to screen is quite easy. The data structures and input processing are the tricky aspects.