[Bf-committers] EGL_CONTEXT_LOST and GL_ARB_create_context_robustness

[Brecht Van Lommel]

I suppose you could clear the zeros and then have some
GPU_texture_lost(..) or GPU_shader_lost(..) functions that checks
them, so that you have code like this? If you don't free the entire
thing you have to write extra code to reconstruct the texture or
shader, easier is just to free it entirely and recreate.

if (!ima->gputexture || GPU_texture_lost(&ima->gputexture)) // will
free the entire GPUtexture if it was lost
     ima->gputexture = GPU_texture_create(..)

... use texture ...


But maybe I'm misunderstanding, what does "reacquiring the resource"
mean? Aren't the actual texture pixels or shader lost? So then the
wrapper can't really recreate it on behalf of the owner, only the
owner knows how to create this data.


On Wed, Jul 31, 2013 at 5:43 PM, Jason Wilkins
<jason.a.wilkins at gmail.com> wrote:
> I'm not sure I follow.  Why would a higher level wrapper need to be freed
> entirely?  Couldn't it reacquire the resource on behalf of whoever is using
> it?
>
>
> On Wed, Jul 31, 2013 at 9:38 AM, Brecht Van Lommel <
> brechtvanlommel at pandora.be> wrote:
>
>> On Wed, Jul 31, 2013 at 2:58 PM, Jason Wilkins
>> <jason.a.wilkins at gmail.com> wrote:
>> > I'd rather centralize the zeroing out so it isn't ad-hoc.  It could be as
>> > simple as a gpuGenTextures that returns GLuint* instead of GLuint.  Then
>> > all that is needed is a std::vector of GLuint held in a central location
>> > that can be zeroed out when there is a context loss.
>> >
>> > The owner of a resource should restore it if it is zero and if something
>> > isn't the owner it should maybe skip whatever it was doing if it finds
>> the
>> > resource missing (it will probably be there next frame).
>> >
>> > If it is a problem for resources with multiple owners to pass the buck on
>> > restoring it, then maybe a pseudo owner should be made that is guaranteed
>> > to restore it if it is missing, and do so before anybody else needs it.
>>  Or
>> > maybe I'm naive and this needs some kind of dependency graph...  I doubt
>> it.
>> >
>> > Some type safety could be added by putting the IDs in a struct.
>> >
>> > struct GPUtexID { GLuint* texID; };
>> > struct GPUvboID { GLuint* vboID };
>> > etc.
>> >
>> > Then you have gpuGenTextures(GLuint n, GPUtexID* idOut);
>> >
>> > I don't think the problem is centralizing the zeroing out process.  I
>> think
>> > the problem is making sure all the code that uses resource is ready to
>> > restore it.
>>
>> This is why I think it should be a higher level thing than wrapping
>> the OpenGL functions. We already have some higher level wrappers for
>> OpenGL data and they would need to be freed entirely, I think we
>> should build things at that level, zeroing out ids is not enough.
>>
>> Brecht.
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