QueryObjects API

[luithefirst]

We need to abstract this functionally behind our rendering API in order to provide all functionality required for my application: https://www.khronos.org/opengl/wiki/Query_Object

The IRuntime should allow creating Queries:

• Time
• SampleCount
• PrimitiveCount
• (AnySample)
• (TimeStamp)

Using a long as result for all types is possible.

Questions:

• Should creating a Query also invoke a Begin or should this be separate? Actually, I like the idea of reusing queries (even they need to be re-created in GL) so a separate Begin/Start seems convenient.
• Should it be a Disposable or cleaned up by Runtime.DeleteQuery (like with textures)? -> It looks we chose this pattern for textures/buffers in order to allow resource management/counting. I would say we can go for a Disposable here.
• Should there be a mechanism to detect conflicts of nested queries of the same type (not supported by OpenGL)?

A query should allow:

• IRuntime.CreateQuery
• Begin/Start
• End/Stop
• HasResult: check if there is a result
• TryGetResult: get result if available
• GetResult: waiting for the result with an optional timeout
• Dispose
• Restart

What about advanced features/interoperability with RenderCommands?

• Feed PrimitiveGenerated to an indirect render command
• Conditional rendering using AnySample

Already found in the GL backend:

• GLTimer in Configfs.
• OpenGlStopwatch in Config.fs
• OpenGlStopwatch in Statistics.fs
• OpenGlQuery in Statistics.fs: Already looks like a usable abstraction of a query, but missing e.g. TryGetResult, silently ignores nested queries?

[hyazinthh]

Implemented queries and an example in https://github.com/aardvark-platform/aardvark.rendering/commit/c87eee3f91b597d2c6e9c16d48c683f360b26959