I have a pretty basic widget rendering, largely based upon the learnopengl.com "hello triangle." I'm actually using a tristrip to create two triangles, forming a semi-opaque square over the top of the other stuff in my window. In this square, I'm using the fragment shader to set the semi-opaque background color and an arrow that points in the direction of flight. What I want to do next is render a
GL_LINES vertex buffer that contains the historical position of the aircraft.
It seems easy enough to set up a second vertex attribute object and vertex buffer, but what is unclear to me is whether it's possible to use a single vertex & fragment shader pair to handle this second dataset. It wouldn't be terribly difficult to set up a group of widgets to render the opaque square, then the historical course information, then the arrow, but I already have the first and third stages working.... and breaking everything up would mean 3 vertex and 3 fragment shaders.
I'm guessing that it's impossible to deal with the semi-opaque background, the historic course, and the arrow all in one vertex/fragment shader pair, but it'd be obtuse to just make that assumption and make a mess out of some tolerably organized code before I got an informed answer.