Re: How to use Annex G.3 Vectors and Matrices in bindings to C arrays

[Gautier <gautier@fakeaddress.nil>]

Yves Bailly:

> So I'm not sure if it's actually possible to correctly pass nD arrays to
> C code... Back again to my OpenGL code, I did things like this:
> type Vector is array(1..3) of Float;
> pragma Convention(C, Vector);
> type Matrix is array(1..3) of Vector;
> pragma Convention(C, Matrix);
> ...and it worked quite well.
> 
> But maybe this pragma works for nD arrays? I'm quite interested in the
> answer (I'll test this as soon as I have some time).

This is at least mentioned in the B.1 annex (verse 2), with exactly the 
example of a nD array's storage.

BTW, in my OpenGL code (GLOBE_3D.Math, body) there is...

   type Matrix_44 is array(0..3,0..3) of aliased Real; -- for GL.MultMatrix
   pragma Convention(Fortran, Matrix_44);  -- GL stores matrices columnwise

HTH, Gautier
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