qualifiers are often used when communicating between the client and shaders, or
are read only and used for declaring variables that don’t change.
values which do not change during rendering, for example the light position or
the light colour. Uniforms are read-only and are passed from the
client to the server. in
variables are coming into a shader, typically from an earlier shader
stage. These variables may not be
from a shader,
typically to a
are no pointers in GLSL.