Ops, it was my fault! :)
I forgot to insert the reset of model view matrix when I draw the 2D image.
Now it's working! Thank you thank you thank you!! ;)
Here's the complete code, if somebody need...

Thanks for your reply.
I changed in this way:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION );
glLoadIdentity();
glOrtho(0,1,0,1,-1,1);...

Hi all!!
I'm trying to create a simple 3D game, and I want to put behind my scene a fixed background image.
I read that I need to draw a textured quad in glOrtho for the background, and to draw my...