[Mesa-dev] [PATCH 1/4] mesa: Add a Version field to the context with VersionMajor*10+VersionMinor.

[Kenneth Graunke]

On 07/27/2012 12:19 AM, Jordan Justen wrote:
> On Thu, Jul 26, 2012 at 11:52 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> On 07/26/2012 05:54 PM, Jordan Justen wrote:
>>> On Thu, Jul 26, 2012 at 5:27 PM, Eric Anholt <eric at anholt.net> wrote:
>>>> As we get into supporting GL 3.x core, we come across more and more features
>>>> of the API that depend on the version number as opposed to just the extension
>>>> list.  This will let us more sanely do version checks than "(VersionMajor == 3
>>>> && VersionMinor >= 2) || VersionMajor >= 4".
>>>> ---
>>>>  src/mesa/main/mtypes.h  |    2 ++
>>>>  src/mesa/main/version.c |    6 ++++++
>>>>  2 files changed, 8 insertions(+)
>>>>
>>>> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
>>>> index 3d59dc6..23d32a6 100644
>>>> --- a/src/mesa/main/mtypes.h
>>>> +++ b/src/mesa/main/mtypes.h
>>>> @@ -3427,6 +3427,8 @@ struct gl_context
>>>>
>>>>     /** Version info */
>>>>     GLuint VersionMajor, VersionMinor;
>>>> +   /** VersionMajor * 10 + VersionMinor, so 31 for GL 3.1. */
>>>> +   GLuint Version;
>>>>     char *VersionString;
>>>>
>>>>     /** \name State attribute stack (for glPush/PopAttrib) */
>>>> diff --git a/src/mesa/main/version.c b/src/mesa/main/version.c
>>>> index efaaf58..697758e 100644
>>>> --- a/src/mesa/main/version.c
>>>> +++ b/src/mesa/main/version.c
>>>> @@ -223,6 +223,8 @@ compute_version(struct gl_context *ctx)
>>>>
>>>>     override_version(ctx, &ctx->VersionMajor, &ctx->VersionMinor);
>>>>
>>>> +   ctx->Version = ctx->VersionMajor * 10 + ctx->VersionMinor;
>>>
>>> How about a macro rather than coding the *10 everywhere?
>>> #define UINT_VERSION(major, minor) ((10*(major)) + (minor))
> 
> I'm not too happy with UINT_VERSION, so maybe GLVER could be a less
> verbose option.
> 
>> Personally I like the major * 10 + minor version, as its clear what it
>> does.  But I wouldn't object too strongly to a macro or inline function
>> either.
> 
> I guess history would seem to indicate that a minor > 9 is unlikely,
> but is this guaranteed?

It does seem very unlikely, given the speed at which major change comes,
but I guess I couldn't say it's impossible.

> Personally, I would prefer:
>   if (ctx->Version < GLVER(major, minor))
> over
>   if (ctx->Version < major * 10 + minor)
> 
> And, I would prefer:
>   if (ctx->Version < GLVER(3, 1))
> over
>   if (ctx->Version < 31)

Yeah, that is definitely more future-proof than relying on 2-digit math.
 I'd be fine with either approach.