Looking for advice on investigating GrGL specific rendering issues (drawMesh?)

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Alexandre Bique

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May 29, 2024, 8:57:40 AMMay 29
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Hi,

We are using Skia in Bitwig Studio (https://www.bitwig.com/).
We have support for Metal, Vulkan, DirectX12 and in last resort OpenGL when we have no other choice.
We only use Ganesh, we've built skia from the branch chrome/126 using vcpkg.

We have some rendering bugs that only happens with Ganesh+OpenGL.

I suspect it is related to drawMesh() which doesn't seem to render anything when using OpenGL.

The comment is saying that drawMesh() is experiemental, should I stay away from it?

I am looking for advice on how to understand what the problem be, eventually fix how we use skia or work it around.

Thank you very much,
Alex

Greg Daniel

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May 29, 2024, 9:00:45 AMMay 29
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Hi Alex,

Are you able to give examples of code that doesn't work for you? If you are able to write something in fiddle.skia.org that would be ideal.

Have you tried stepping through the code at all for drawMesh to see if you hit any failure cases?

Greg

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John Stiles

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May 29, 2024, 9:01:04 AMMay 29
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drawMesh() should be usable even in OpenGL. It's not experimental. However, it doesn't work in the software rasterizer. 

Are you sure the surface isn't a software surface?

Can you give any more details about the issue? 

Thanks. 

On Wed, May 29, 2024 at 8:57 AM Alexandre Bique <bique.a...@gmail.com> wrote:

Alexandre Bique

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May 29, 2024, 9:03:48 AMMay 29
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Hi Greg,

No I haven't stepped through the code yet.
I'll try to isolate that issue but it is a bit hard, so far our unit test rendering are working fine, but when rendering the full application window, it seems to produce different results.
Let's see if I can get a small test case.

Thanks!

Alexandre Bique

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May 29, 2024, 9:05:43 AMMay 29
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Hi John,

I'm pretty sure the surface is HW accelerated, but I'll add a check for that to make sure.
That'd be the ideal outcome if the surface was rasterized by mistake!

Thanks!

Alexandre Bique

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May 29, 2024, 12:54:29 PMMay 29
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Hi John,

You had the correct guess.
I had a surface that wasn't GPU based (only when using OpenGL) and this was the source of the error.

Thank you so much for your help.

Alex

John Stiles

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May 29, 2024, 4:54:30 PMMay 29
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That's great to hear! Thanks for reporting back.

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