Preprocessor directives:

• #error:  cause the implementation to put a diagnostic message into the info log
• #version: declare the version of GLSL they are written in.  If not included, version 1.10 is assumed.  The vertex and fragment shaders should have the same version.  The #version directive should appear first if used.  Example:

                   #version 400

• The version can be core as well

                   #version 400 core

High