[mythtv] #13351: Add OpenGL ES configurability/autodetection

[Stuart Auchterlonie]

On 27/11/2018 11:21, Piotr Oniszczuk wrote:
> Peter,
> 
> As far as I reading code - usage gles is possible only on Android and currently is used only for android:
> https://github.com/MythTV/mythtv/blob/9c940817da8aa001219bbded26b26f12a7b364b7/mythtv/configure#L6566
> There is no way in myth to use gles on other platforms.
> 
> I think we should address 2 things:
> 
> 1.Selection in configure to use gles when OS proves OpenGL Desktop _and_ OpenGL ES

I'd like to be able to switch between the 2 at runtime in this
case. I don't believe there is a technical reason why this
isn't possible

> 
> 2.Working myth when OS provides _only_ OpenGL ES
> 

I thought we already had this on embedded platforms
such as the rpi?


Regards
Stuart


> Patches in #13351 already are working OK for case 1)
> 
> For case 2) situation is a bit more complicated as first I need to prepare OS providing GL and Qt only at OpenGL ES level (which is not trivial).
> I already have working configure+building for case 2) - but resulting code not working with GL painter. 
> I don’t yet know why.
> To sort this first I must investigate:
> a) is this issue of underlying OS (most probably Qt5)
> b) or this is issue of myth (effectively current master can’t work with GL painter without OpenGL Desktop API available - even if conditional USING_OPENGLES is set at building)  
> I suspect my issue is a)
> 
> To investigate further: can anybody from android world confirm me that:
> - android provides _ONLY_ OpenGL ES?
> - do android has libGL.so and include/GL/*.h files?
> - how config.summary from Qt5 configure looks like in android build?
> 
> Why all this?
> Because almost standard in embedded systems is no OpenGL Desktop and only GLES.
> Without this I can’t move forward with myth on ARM platforms with linux (not android) on platforms where there is no working Mesa yet.
> 
> thx in advance!
> 
> 
> 
>> Wiadomość napisana przez Peter Bennett <pb.mythtv at gmail.com> w dniu 26.11.2018, o godz. 19:39:
>>
>>
>>
>> On 11/25/18 2:37 PM, Piotr Oniszczuk wrote:
>>> Hi,
>>>
>>> Working on ARM HW (AmLogic s905, RPI) I need OpenGL ES support in myth.
>>>
>>> I added OpenGL ES configurability and it works in following way: there is new configure switch: —enable-opengles
>>>
>>> Overall logic: OpenGL ES is disabled by default (if no switch passed to configure or —disable-opengles passed to configure)
>>> If —enable-opengles is passed to configure, configure will detect all required and set conditional USING_OPENGLES if all is OK.
>>> If anything is missing - configure will exit with error.
>>>
>>> So summarising:
>>>
>>> A) ./configure WITHOUT —enable-opengles
>>>
>>> Result:
>>> OpenGL ES disabled; what OS provides doesn’t matter
>>> USING_OPENGLES is not set
>>>
>>> B) ./configure WITH —enable-opengles
>>>
>>> B.1) System has proper support for OpenGL ES. This means:
>>> a) pkg-config present to EGL and GLESv2
>>> b) *.h, GLESv2 libs are present
>>> c) Qt provides Open GL ES
>>>
>>> Result:
>>> configure sets USING_OPENGLES
>>>
>>> B.2) System has broken support for OpenGL ES
>>> (any of a) or b) or c) from B.1 are not valid)
>>>
>>> Result:
>>> configure exits with error
>>>
>>> Why exit with error?
>>> If user asks for OpenGL ES but system is not properly prepared to build, user should be explicitly notified by this issue.
>>>
>>>
>>> This way current build bots should still work ok.
>>> Only change is required for android building: now it requires adding —enable-opengles to configure params
>>>
>>> I tested it on x86 and RPI3 with fully working OpenGL ES.
>>>
>>> Let me know what You think
>>>
>>>      
>> What is the problem with the current setup? OpenGL ES is already used in android and raspberry pi, and as far as I know it is already enabled if the correct libraries are present.
>>
>> Peter
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