[m-rev.] for review: mercury_opengl changes

[Peter Wang]

On 2006-12-05, Julien Fischer <juliensf at csse.unimelb.edu.au> wrote:
> 
> On Tue, 5 Dec 2006, Peter Wang wrote:
> >extras/graphics/mercury_opengl/mogl.m:
> >	Add bindings for glTexImage1D, glTexImage2D, glTexImage3D,
> >	glCopyTexImage1D, glCopyTexImage2D.
> >
> >	Move the pixel_data type into the interface.
> >
> >	Import mogl.type_tables.
> >
> >extras/graphics/mercury_opengl/mogl.type_tables.m:
> >	New module.  This is intended to expose some of the <type>_to_int and
> >	<type>_flags[] tables.  Modules other than mogl can import this 
> >	module
> >	to convert mogl types to their equivalent OpenGL constants.
> 
> Is this a particularly useful thing to be able to do?

In my case I'm using a separate library to load textures, and it accepts
OpenGL texture format flags.

> (Actually, I was hoping to use the foreign_export_enum stuff I've been 
> working on to eliminate the need for most of the <type>_to_int predicates).

I don't mind if the module's interfaces change later.

> >	Add pixel_format and pixel_type conversion tables.
> >
> >	Move texture_format conversion tables from mogl to here.
> >
> 
> Which version of the OpenGL spec are these changes targeted at?

1.1.

> >Index: mogl.m
> >===================================================================
> >RCS file: 
> >/home/mercury1/repository/mercury/extras/graphics/mercury_opengl/mogl.m,v
> >retrieving revision 1.22
> >diff -u -r1.22 mogl.m
> >--- mogl.m	31 Aug 2006 11:09:50 -0000	1.22
> >+++ mogl.m	5 Dec 2006 04:22:03 -0000
> >@@ -521,6 +534,34 @@
> >:- pred tex_gen(texture_coord::in, texture_gen_parameter::in,
> >    io::di, io::uo) is det.
> >
> >+:- inst border ---> 0 ; 1.
> >+
> >+:- type pixel_data.
> >+:- pragma foreign_type("C", pixel_data, "const GLvoid *").
> 
> I suggest hiding the foreign_type decl in it's own little interface
> section, rather than including it in the "public" interface.

Ok.

> What's responsible for managing the memory required by the texture
> data?  (It was never entirely clear to me whether textures are
> copied to the server or if the reside on the client side.  There's
> no problem for the former; there may be for the latter, e.g.
> if the memory was allocated by the garbage collector and we no longer
> maintain a reference to it.)

The former (i.e. it's copied).

> >+%------------------------------------------------------------------------------%
> >+
> >+:- module mogl.type_tables.
> >+:- interface.
> >+
> >+:- func pixel_format_to_int(pixel_format) = int.
> >+
> >+:- func pixel_type_to_int(pixel_type) = int.
> >+
> >+:- pred texture_format_to_int(texture_format, int).
> >+:- mode texture_format_to_int(in, out) is det.
> >+%:- mode texture_format_to_int(out, in) is semidet.
> 
> Why is that mode commented out?

I just copied it verbatim from mogl.m.

Peter

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