Statically link SDL2 to make our samples (glTF Viewer, etc.) completely
standalone, and include missing resources (fonts and default environment
map for the IBL).
I tested this by viewing CesiumMan with our `gltf_instances` sample app.
There is now a need for some general refactoring in gltfio. I feel that
the high-level objects have become too tightly coupled to each other.
Fixes#3137.
Note that this API is on the loader rather than the asset. This is
because the loader knows how to create Filament entities by traversing
a cgltf node hierarchy.
Animation on dynamically added instances is not yet supported.
We did not add destroyInstance() because gltfio favors flat arrays for
long term storage of entity lists and instance lists, which would be
slow to shift. We also wish to discourage create/destroy churn since it
is more efficient to pre-allocate instances and selectively add them
into the scene.
Fixes#3137.
This introduces the `viewer::Settings` struct, and a JSON reader /
writer.
This will be used for automated testing and for client / server
communication.
Note that `viewer::Settings` is closely associated with the
`filament::View` API; when updating the latter we will often need to
update the former, as well as some serialization code. This increases
the maintenance burden and I think we should consider using a parser
library like libclang or a macro-based reflection utility.
This PR also migrates SimpleViewer into libs/viewer and un-inlines its
implementation. It does not belong in gltfio because it has an imgui
dependency.
