Upcoming Qt switch to OpenGL ES on arm64

[Alan Corey]

Try glxgears and es2gears on few different platforms.  On a Pi 3b
glxgears runs at about 45 FPS, es2gears slightly lower.  On my Rock64
it's in the hundreds of FPS but that's Mali.  Look at omxplayer, full
screen HD video while the CPU idles (on a Pi).  The GPU is more
capable than the CPU.  You can do software-emulated OpenGL on
anything, the question is how efficient it is.

On 11/26/18, bret curtis <psi29a at gmail.com> wrote:
> Hello Ian,
>
> On Mon, Nov 26, 2018 at 2:04 PM Ian Campbell <ijc at debian.org> wrote:
>>
>> On Mon, 2018-11-26 at 12:07 +0100, bret curtis wrote:
>> > The hardware that supports GLES also supports OpenGL because GLES is
>> > a subset of OpenGL.
>>
>> I'm confused by this inference. If GLES is a subset of OpenGL then
>> surely hardware which claims to implement GLES is at liberty to only
>> implement that subset and would therefore not necessarily support
>> OpenGL.
>>
>> Ian.
>>
>
> I believe this is a purely a driver/firmware distinction. So whoever
> implements this is at liberty to do whatever they want so long as the
> hardware supports it.
>
> Meaning that if something advertises GLESv2 support then it has, at
> least, OpenGL 2.0 support in hardware because without that, they
> couldn't have supported GLESv1.
>
> GLES1.1 is fixed-function pipeline that is compatible with OpenGL 2.0,
> you're not going to create hardware to support GLES1.1 that doesn't
> also support at least OpenGL 2.0
>
> GLESv2 is another beast, it dropped fixed-function pipeline because
> that was the spec, but it is still a software implementation and
> doesn't mean that it no longer exists in hardware.
>
> Take for example the Nvidia Tegra:
> https://opengles.gpuinfo.org/displayreport.php?id=690  <-- SHIELD
> Android TV which happens to be a Tegra SoC  supports OpenGL ES 3.2
> https://opengl.gpuinfo.org/displayreport.php?id=2377  <-- Tegra as
> integrated with CPU (nvgpu), supports OpenGL 4.6.0
>
> Similar (if not the same?) hardware, running aarch64, the only real
> difference is the driver.
>
> That being said, I would love to hear from someone who actually makes
> these things to comment. It is entirely possible that there is a chip
> out there that supports GLES 3.2 and only that in hardware. I would be
> amazed but I'm reluctant to ever use the words never and ever. So far,
> the hardware that supports that are[1]:
>
> Adreno 420 and newer
> AMD GCN-architecture
> Intel HD Graphics Skylake and higher
> Mali-T760 and newer
> Nvidia GeForce 400 series (Fermi)
>
> As I said, I would be amazed if these GPUs didn't support some minimal
> version OpenGL in hardware. As I said elsewhere, most free and
> open-source drivers (mesa) support both some version of GLES along
> with some version of GL. [2]
>
> Cheers,
> Bret
>
>
> [1] https://en.wikipedia.org/wiki/OpenGL_ES#OpenGL_ES_3.2_2
> [2] https://mesamatrix.net/
>
>


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