This finishes the first phase of the FBX2glTF refactor, breaking utility classes out where things were getting too monolithic.
There is an equally important cleanup phase coming where we wrench all the various parts of this code, including the historical ones that we've rarely touched as yet, into a single C++ style paradigm, and modernise everything to C++11 at least.
But for now, we're just picking the pieces back on the floor so we can push 0.9.6 out. It's been far too long since a release.
Did not mean to commit/push the current state of master. But rather than
mess up source control history with a force push, I'll just try to hurry
to a stable point.
This adds the first FBX PBR import path. Materials that have been
exported via the Stingray PBS preset should be picked up as native
metallic/roughness, and exported essentially 1:1 to the glTF output.
In more detail, this commit:
- (Re)introduces the STB header libraries as a dependency. We currently
use it for reading and writing images. In time we may need a more
dedicated PNG compression library.
- Generalizes FbxMaterialAccess to return different subclasses of
FbxMaterialInfo; currently FbxRoughMetMaterialInfo and
FbxTraditionalMaterialInfo.
- FbxTraditionalMaterialInfo is populated from the canonical
FbxSurfaceMaterial classes.
- FbxRoughMetMaterialInfo is currently populated through the Stingray
PBS set of properties, further documented in the code.
- RawMaterial was in turn generalized to feature a pluggable,
type-specific RawMatProps struct; current implementations are,
unsurprisingly, RawTraditionalMatProps and RawMetRoughMatProps. These
are basically just lists of per-surface constants, e.g. diffuseFactor or
roughness.
- In the third phase, glTF generation, the bulk of the changes are
concerned with creating packed textures of the type needed by e.g. the
metallic-roughness struct, where one colour channel holds roughness and
the other metallic. This is done with a somewhat pluggable "map source
pixels to destination pixel" mechanism. More work will likely be needed
here in the future to accomodate more demanding mappings.
There's also a lot of code to convert from one representation to
another. The most useful, but also the least well-supported conversion,
is from old workflow (diffuse, specular, shininess) to
metallic/roughness. Going from PBR spec/gloss to PBR met/rough is hard
enough, but we go one step sillier and treat shininess as if it were
glossiness, which it certainly isn't. More work is needed here! But it's
still a fun proof of concept of sorts, and perhaps for some people it's
useful to just get *something* into the PBR world.
We are at liberty to order our JSON any way we like (by spec) and we can
improve readability a lot by doing so. By default, this JSON library
uses an unordered map for objects, but it's relatively easy to switch in
a FiFo map that keeps track of the insertion order.
Par Winzell
Par Winzell