Chapter 13

1. Which steps of the OpenGL render pipeline are user-definable? Which steps must be defined in order to render anything? You may need to reference the documentation at https://www.khronos.org/opengl/wiki/Rendering_Pipeline_Overview.

The vertex processing and fragment shader steps are user-definable. At a minimum, you must create a vertex shader and a fragment shader. Optional steps include the geometry shader and tessellation steps, which are part of vertex processing.

2. You're writing a shader for an OpenGL 2.1 program. Does the following look correct?

   #version 2.1

   attribute highp vec4 vertex;

   void main (void)
   {
   gl_Position = vertex;
   }

Your version string is wrong. It should read #version 120, since it specifies the version of GLSL, not the version of OpenGL. Versions are also specified as a three-digit number with no period.

3. Is the following a vertex...