firstly thanks for your quick replies.
@jesse, you make a very good point about understanding the content before compiling. This is what I'm trying to do, chapter by chapter but i was totally stumped with this one.
Thanks for pointing out that the output vertex variables need to be named the same as the input fragment ones...that was a detail I missed!
@Luke, much thanks for those bugfixes; the problem i was hitting is fixed. it was indeed one of the problems referred to in the fix notes:
* Since release, certain drivers (specifically AMD) started requiring precision qualifiers in the fragment shader causing the examples to fail while compiling the shader. All shaders are now fixed and an accompanying document gives a brief explanation of the issue.
I did notice that one of the other bug-fixes is not fixed (as far as I can tell):
An incorrect size was passed to glGetShaderInfoLog causing any log output to be truncated.
I'm guessing this is Luke Benstead...if so, thanks for writing a clear and readable book. One suggestion I would make is to place links to these bug-fixes on:
as the book says that's the support web-site and there's currently no support available there.
Again, thanks for your help. It's great to see a friendly and helpful community. Hopefully i can give some back down the line