The immutable inverse bind matrices can be shared among instances, so
they are now stored in Asset, not in Instance.
Also, there are now two "load" phases for skinning data:
(1) storing the inverse bind matrices
(2) building the Entity mappings (for animation efficiency)
Phase 1 is done in `ResourceLoader` because inverse bind matrices can
live in an external bin file.
Phase 2 is done during Instance creation, because that's when entities
are created.
This change was motivated by some internal work at Google and has the
benefit of simplifying the gltfio API and implementation. There are 2
major API changes:
(1) Consolidate separate loader entry points for GLB and GLTF.
The distinction between GLB and GLTF can be made from the file content
alone, because GLB has a 4-byte magic string in its header. There is no
need for separate entry points. Clients do not (and should not) need
to check the file name extension.
(2) Remove the distinction between "instanced" and "non-instanced"
glTF assets.
In the new scheme, all assets have at least 1 instance.
Broadly speaking, in gltfio an "asset" is a collection of Filament
objects like textures and vertex buffers, while an "instance" is a
collection of entities and components (e.g. the transform hierarchy).
This API change makes life easier for clients because they no longer
need to decide a priori if they will ever need to add instances.
This change also moves some public-facing methods from FilamentAsset to
FilamentInstance:
- getSkinCount, getSkinNameAt
- getJointCountAt, getJointsAt
- attachSkin, detachSkin
This optimizes and cleans up some code from a 3P contributor.
When computing a bounding box, there was no need for an inner loop
through the entire skins array.
Tested using the torus model in #4973 and the `-r` flag in gltf_viewer.
* gltfio: Add internal MorphHelper, enable up to 255 targets.
Previously, gltfio could not animate models with more than 4 morph
targets. Now we can handle up to 255 targets, as long as no more than
4 targets are ever used simultaneously. This allows us to handle
many more models, such as those exported by Modo, and the horse model
in #1852.
We do this by picking the highest 4 weights. The indices for these
weights are called the "primary indices", and we construct a new
VertexBuffer for each unique set of primary indices.
In the near future this will be made more efficient by adding a new
VertexBuffer API to the Filament core.
Fixes#1487.
* Code review fixups.
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.
The gltfio API allows users to destroy ResourceLoader or FilamentAsset
even when various asynchronous work (e.g. uploading buffers to the GPU)
has not yet been completed. This was achieved in an error-prone manner
using manual reference counting and an internal management object called
AssetPool.
This PR refactors gltfio by wrapping cgltf_data in shared_ptr, which I
usually try to avoid. However in this case it provides the precisely the
functionality that is needed.
I tested this PR for memory leaks and crashes by hacking gltf_viewer
and monitoring memory usage in Activity Monitor.
This fixes#3383 and makes it easier to implement some missing features,
such as animation support for instanced assets.
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.
Release builds do not call cgltf_validate() so it was possible to
read out-of-bounds animation data when encountering a badly formed glTF
file with mismatched counts between sampler inputs and outputs.
When animation is applied to the master asset, all instances are
animated.
Instances can also be individually animated via the Animator in
FilamentInstance.
Fixes#1513.
This adds createInstancedAsset() to AssetLoader, which creates a master
asset and a set of slave instances. Vertex buffers, index buffers,
textures, and material instances are shared. Entities and components are
duplicated.
Instances have their own API object that is very simple. Light sources
and material instances are not instanced, so are not accessible through
the instance API object.
The master-slave ownership model lets us avoid complex shared ownership
semantics. The existing cache structures in AssetLoader allow the
implementation of this feature to be fairly simple.
The master asset exposes the union of all entities and allows clients to
modify all instances en masse if they wish. This design also works
naturally with ResourceLoader, which does not need to know about
instancing. For example, asynchronous loading is completely unchanged;
the dependency graph simply contains the union of entities across all
instances.
Support for animation is added in a subsequent commit.
Fixes#1513.
* Introduce AssetPipeline for performing glTF manipulations.
AssetPipeline offers a place for doing things like scene flattening,
transform baking, and optimization of glTF assets. These types of scene
manipulations will allow us to tackle lightmap baking in the upcoming
atlasgen tool.
This initial PR includes support for scene flattening, which is fairly
non-trivial. Support for parameterization via xatlas will be added in a
subsequent PR.
In a glTF asset, a single mesh can be referenced by several nodes, and
each reference can have a unique transform. AssetPipeline can flatten
the asset such that each instanced mesh has its own vertex data, and the
node transform gets baked into the vertex data.
Recall that gltfio is composed of two libraries: the core library (no
filamat) and the full library. This adds to the size of the full library
but leaves the core library as is.
* Fix various Windows build issues.
- Add support for CUBICSPLINE and STEP interpolation methods.
- Use cgltf_accessor_read_float() instead of manually unpacking values.
- Fix potential NaN in decomposeMatrix.
- Reduce malloc churn by stashing the vector of bone matrices.
This is our new mobile-friendly and web-friendly library for loading
glTF assets. It is still a work in progress, but already capable of
loading many conformance models, including those with animation,
skinning, and a couple of extensions (nonlit and texture transforms).
Next week we will add a sample app demonstrating its usage.
