Update to Magnum with a magic shader flag & Python bindings for scene export

[mosra]

Motivation and Context

What's new:

• Utility::Arguments now support both the --option value and --option=value form for better consistency with usual Unix tools
• GL::Renderer::setDepthRange() and related additions to the GL library for enabling better-precision and reverse depth buffers
• MeshTools::generateIndices(), which converts strips/fans/loops to standalone primitives, now works also with already-indexed meshes for more convenience
• Shaders::PhongGL::Configuration::setLightCount() now decouples total passed light count from how many lights to use per draw for more optimal codegen with light culling enabled
• New Flag::ShaderStorageBuffers (i.e., the ✨ magic flag ✨ that didn't make it into Update to Magnum with new MaterialTools and improved glTF import/export #2015) in all builtin shaders, which -- compared to uniform buffers -- allows them to have the uniform arrays of unbounded size. This makes it possible to easily render huge Floorplanner scenes consisting of tens of thousands of materials and thousands of draw calls. The tradeoff is that it may be slower than uniform buffers and doesn't work on macGL (which is stuck on GL4.1) and WebGL, meaning it's still worth to reduce the material / draw count in the datasets. On the other hand this feature translates directly to Vulkan, Metal and WebGPU so it isn't a work wasted on something GL-specific.
• And more! 🤫

Python bindings have the following new APIs exposed. This is the bulk I showcased last Thursday with the density-aware decimation script:

• Exposed essentials of utility.ConfigurationGroup together with pluginmanager.PluginMetadata.configuration and pluginmanager.AbstractPlugin.configuration, which finally allows specifying plugin configuration, unblocking quite a few previously-impossible use cases.
• Exposed trade.AbstractSceneConverter.convert() and trade.AbstractSceneConverter.convert_in_place() for mesh-to-mesh conversion, such as optimizing and decimation with MeshOptimizerSceneConverter.
• Exposed the batch file conversion API of trade.AbstractSceneConverter. There's add_importer_contents() for direct passthrough of importer contents to the converter, the singular add() API is exposed for just trade.MeshData at the moment.

On the Python front I'll be exposing texture- and material-related properties next, to allow density-aware image resizing similar to meshes.

How Has This Been Tested

My CIs are 🟢

[jturner65]

LGTM

[jturner65]

Does this upgrade include the changes you made for the mesh optimizer?

[mosra]

Which ones do you mean specifically? The full API is exposed but the meshoptimizer submodule isn't added and the related plugins are not enabled either as I felt those would be a dead weight for 99% users.

Related post on Slack -- let's discuss there.

[0mdc]

Thank you!