[Webkit-unassigned] [Bug 58498] WebGL should create a single-sample context if creating multisampled context fails

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=58498





--- Comment #7 from Naoki Takano <takano.naoki at gmail.com>  2011-06-20 10:54:14 PST ---
I see, I'll look into it more.

BTW, this is a quite a bit different question. But do you know SKIA_GPU flag? Is the bug related to this flag? If so, how can I turn it on?

Thanks,

(In reply to comment #6)
> Ah sorry for confusing you.
> 
> GraphicsContext3DOpenGL.cpp is used by webkit Mac port (Safari).
> 
> For chromium, the in-process port is in chromium tree under src/webkit/gpu/webgraphicscontext3d_in_process_impl.cc:reshape();
> 
> the command buffer port is under the same folder, but you need to dig deeper into the command buffer code to add the behavior, and reshape function is the entry.
> 
> 
> 
> (In reply to comment #5)
> > Mo,
> > 
> > Sorry for bothering you.
> > 
> > But I want to make sure the source code you suggested.
> > 
> > Right now, I'm mainly working on Chromium source code base. And even after I change something in GraphicsContext3DOpenGL.cpp, I cannot see anything when I run 'make'. As you know, if we change anything for the source code, we should be able to see compile process when 'make'.
> > 
> > I checked on Linux and Mac. But I cannot see any compilation on both platforms.
> > 
> > Is this source cod used by Chromium port? Or do I need to set extra build setting to use this portion?
> > 
> > Thanks,
> > 
> > (In reply to comment #4)
> > > We don't exactly know on which hardware the multisampled FBO creation might fail.  You'll have to emulate failure in the multisampled path to test the recovering and fallback to non-multisampled path.
> > > 
> > > (In reply to comment #3)
> > > > Thanks, Mo.
> > > > 
> > > > So can we reproduce on any Mac environment?
> > > > Do we need any specific hardware configuration, such as GPU type?
> > > > 
> > > > (In reply to comment #2)
> > > > > One place you can look at is webcore/platform/graphics/opengl/GraphicsContext3DOpenGL.cpp, reshape function.
> > > > > 
> > > > > In that function, if m_attrs.antialias is true, then we try to create a multisampled FBO for rendering.
> > > > > 
> > > > > Currently that code path doesn't recover from error.  So what we need to do is
> > > > > 
> > > > > 1) check if creation of multisampled FBO succeeds or not.
> > > > > 2) if it failed, set m_attrs.antialias = false, and try again.
> > > > > 
> > > > > One thing unclear to me is that it seems attributes.antialias might change in the lifetime of a context.  I am not sure if it's OK or not.
> > > > > 
> > > > > Hope this helps.

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