In this first step, we just "blindly" move everything under src/driver
to a new library libbackend.a. And all headers are moved under
private/backend.
Note that "driver" is renamed "backend", but namespaces are unchanged for now.
Later we'll have to untangle the actual private headers from public
ones and ideally not have any private headers.
Assimp's CalcTangentSpace deviates from de facto glTF 2.0 so we were
compensating for this with an unconditional fixup in MeshAssimp. However
the fixup should apply only when CalcTangentSpace is active, i.e. when
the model is missing tangents.
This makes it so that NormalTangentMirrorTest (has tangents) and
NormalTangentTest (needs tangents) both look reasonable.
I also noticed that MeshAssimp was inexplicably applying
aiProcess_CalcTangentSpace twice: once as a flag, and once as a
post-process. I removed the latter.
This will be fixed in the upcoming cgltf-based loader, which will
use our officially-sanctioned utility method in VertexBuffer.
See #528
- baseColorFactor.a was not taken into account
- Some glTF files do not set `doubleSided` properly, so here we assume
that non-opaque materials are double-sided. We may need to revisit
this decision later...
* grouped MeshAssimp arguments into struct
* added snormuv optimization to MeshAssimp and changed snormuv optimization range from [0, 1] to [-1, 1] in filamesh
We started to write our own implementation of mikktspace, but it
required an unindexed mesh for input. This was awkward because assimp is
already applying a pipeline of operations that includes tangent
generation and indexing. It felt reduandant to add our own pipeline on
top of that (unindexing => tangentgen => reindexing).
Since assimp's CalcTangentsProcess method is already producing
tangents that follow the orientation implied by texture coordinates,
this simply needs to be tweaked to match glTF. (flip the bitangent)
Also fixed a bug for the case where models have neither UV's nor
tangents, where we were calling norm instead of normalize. :)
* Revert "Rollback MeshAssimp enhancements."
This reverts commit b3dce967eb.
* Re-enable glTF support
* Start looking for texture ids at 1, not 0
* Detect if the importer is glTF
* glTF and regular materials both work
This caused regressions with some of our samples like vk_hellopbr:
- For the new 1x1 textures, RGB isn't accepted by Vulkan and Metal.
Currently these platforms require RGBA, although we plan on adding
reshaping functionality for the future.
- Too many texture samplers in a single shader, this causes a run time
error. This could be alleviated by creating an atlas.
- vk_hellopbr assumes that all materials have a "metallic" param.
Going forward, we plan on creating a new library that avoids MeshAssimp,
so for now let's just disable gltf_viewer.
