The vertex shader is pretty simple. It passes the normal and position along to the geometry shader after converting them into camera coordinates. The built-in gl_Position variable gets the position in clip coordinates. We'll use this value in the geometry shader to determine the screen space coordinates. In the geometry shader, we begin by defining the input and output primitive types for this shader:
layout( triangles ) in; layout( triangle_strip, max_vertices = 3 ) out;
We don't actually change anything about the geometry of the triangle, so the input and output types are essentially the same. We will output exactly the same triangle that was received as input. The output variables for the geometry shader are GNormal, ...
