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

[Jordan Justen]

On Fri, Jul 27, 2012 at 6:47 AM, Brian Paul <brianp at vmware.com> wrote:
> On 07/27/2012 01:51 AM, Kenneth Graunke wrote:
>>
>> 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.
>
>
> How about a simple inline helper function like this:
>
> /**
>  * Check if the OpenGL version is greater than or equal to "major.minor"
>  */
> static inline GLboolean
> _mesa_have_version(const struct gl_context *ctx, int major, int minor)
> {
>     return ctx->Version >= major * 10 + minor;
> }

Yeah, that seems good:
if (!_mesa_have_version(ctx, major, minor))
if (!_mesa_have_version(ctx, 3, 1)) /* ver < 3.1 */

And, can we add this nearby so both are easily changed:
static inline void
_mesa_set_version(struct gl_context *ctx, int major, int minor)
{
    ctx->Version = major * 10 + minor;
}

-Jordan