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fabio

OpenGL 3 extensions

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I incidentally noticed in this commit that 0 A.D. can use some OpenGL 3 features like GL_EXT_transform_feedback and GL_ARB_geometry_shader4.

What are they used for? I am asking because they are going to be implemented soon in mesa (see e.g. transform feedback patch) and I'd like to know what to expect from them (performance, improved rendering, ...).

Also it would be nice if the game prints on stdout (or on a dedicated menu inside the game) all the probed extensions and their availability (as for example do id software games).

Lastly, what about the OpenGL capabilities database? It looks like it's no longer updated.

Thanks :)

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These questions are all directed at Philip, but maybe I'll save him some time :)

IIRC, the shaders were intended to simplify the code and reduce the number of combinations that had to be implemented.

Shaders sometimes decreased the performance, but can also lead to improvements vs. equivalent fixed-function stuff.

I do not know the rationale for the OpenGL3+ extensions. They're not currently in use - perhaps only for completeness or for other applications.

We could print the extensions, but I am wondering as to the intended application.

It would be possible already to grep for ogl_HaveExtension and gather the list, and then match that against those reported in logs/system_info.txt .

The capabilities database requires an analysis tool to be run on the server; that needs to be triggered manually, and I guess it hasn't been done in some time.

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I incidentally noticed in this commit that 0 A.D. can use some OpenGL 3 features like GL_EXT_transform_feedback and GL_ARB_geometry_shader4.

What are they used for?

They're used for the OpenGL capabilities database, and nothing else.

Lastly, what about the OpenGL capabilities database? It looks like it's no longer updated.

I've been meaning move all my stuff onto a newer server (with bigger disk and newer software) and then update that database (and update the code since the latest data triggers some bugs), but haven't got around to moving yet :(. But I still mean to do it, some time soonish.

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