Because storing arbitrary data as a string was not good:
- It *never* followed alignment requirements due to the last byte being
used for size. Instead the size is now stored before the data, and
thus the data is always on the 64 byte boundary.
- As it could contain arbitrary binary data, it could cause
magnum-sceneconverter --material-info to print garbage, corrupt the
terminal or, worst case, crash. Not good.
- It stored an implicit \0, which was unnecessary.
There's no reason for those to exist anymore -- origiinally they were
added in a hopeful attempt to make use of parallel shader compilation,
but in practice that meant compiling at most two or three shaders at
once and still stalling until that was done, so not that great at all.
The new APIs provide much better opportunities for parallelism.
Fun fact:
CORRADE_INTERNAL_ASSERT_OUTPUT(vert.compile() && frag.compile());
is actually one character shorter than
CORRADE_INTERNAL_ASSERT_OUTPUT(GL::Shader::compile({vert, frag}));
so not even typing convenience would be a reason to keep these.
The new async APIs were just checking the link status, and printing the
linker error. Because drivers commonly do all that in a single step,
without really separating compilation from linking (or at least that's
what I thought?), I assumed the linker error would contain *also* the
compilation error, if any.
But on a quick check with Mesa that's not the case, I only get "error:
linking with uncompiled/unspecialized shader", which is very useless.
Which means, to get proper error output, the checkLink() function now
explicitly takes a list of the input shaders. It will unconditionally go
through them at the beginning and call checkCompile() on each.
To further encourage the shaders to be passed, there's no default
argument -- so if the application calls checkCompile() on its own for
some reason, it has to pass an empty list to checkLink().
Because it somewhat confusingly may have implied that it's really
composed of 8-bit bools, and not bits. The same reasoning was used to
pick the name for Corrade's Containers::BitArray.
Backwards compatibility aliases are in place as usual, however the
internal BoolVectorConverter is now BitVectorConverter and there
unfortunately cannot be any backwards compatibility. This breaks only
GLM and Eigen integration in the magnum-integration repo, which I'm
fixing immediately. I don't expect any user code to use this internal
helper. For regular vectors maybe, for this one definitely not.
Similar to the change done in Corrade, see the commit for details:
878624ac36
Wow, this is probably the most backwards-compatibility code I've ever
written. Can't wait until I can drop all that.
The boring dry usage info grew significantly, and listing it as the
first thing on the page would scare people off. Put the examples first
instead, and for the imageconverter and sceneconverter add --info
listing examples, as that's what is eye-catchy.
While branching on a compiler is rather common, checking a particular
compiler version should be needed only rarely. Thus minimize use of such
macros to make them easier to grep for.
Here the benefit is especially clear -- as Containers::Pair is trivially
copyable with trivial types, all growable arrays can make use of
std::realloc() while with the STL variant a silly constructor, copy
constructor, destructor had to be used.
Additionally, we no longer need to take explicit care of libc++ and MSVC
STL where returning a std::pair<bool, Containers::String> as
return {{}, Containers::String{..., <deleter>}};
would caused an unnecessary copy instead of a move, losing the custom
deleter in the process. Yay!
There's a <Corrade/Containers/PairStl.h> include for backwards
compatibility purposes, but obviously it would only work for the return
type of validate*() and cases where an initializer list was passed to a
list-of-pairs-taking functions, and not a concretely typed ArrayView.
Those functions were though mostly the linker API which isn't
implemented by any plugin yet, so it shouldn't be *that* breaking to
users. Neverteless, I'm trying to do this breaking change rather sooner
than later to prevent pain further down the road when the Vulkan APIs
and SPIR-V pipeline gets widely used.
It limits the support for CMake 3.12+, but it's much less verbose and I
don't expect people to use ancient CMake versions with IDEs like Xcode
or VS anyway, so this should be fine.
Like in Trade, the unatomic exists() + read() pair (and silent failures
if the file exists but can't be read) was replaced with just
Path::read() that now returns an Optional. Besides that, not much worth
mentioning.
For file opening there's no longer an unatomic pair of exists() +
read(), but since Path::read() now returns an Optional, it means we can
reliably distinguish between empty files and failures.
While at it, also added TODOs for removal of the StringStl.h header
that's needed in various places for compatibility with APIs still using
STL strings.
Basically mirroring the changes done for Corrade::Compare::*File*,
including storing the filenames as string views to avoid unnecessary
copies (and then paying extra attention to not pass temporaries to them
in its own tests).
Mainly to have feature parity with Flat and Phong -- otherwise switching
to draw a wireframe on an instanced mesh would be too annoying. Also, if
we have multidraw there already, why not instancing as well.
Also not something the classic GPU vertex pipeline can handle, but
useful for other scenarios. Subsequently a support for array indices
will be added, allowing to directly represent for example OBJ files,
where each attribute has its own index buffer.
This is not something the classic GPU vertex pipeline can handle
(except maybe Vulkan, which can handle zero strides for instanced
attributes?), but useful for other scenarios. This means existing code
needs to be aware of and handle the new corner case.
Same as with MeshData2D/3D, the original ObjectData API and plugin
interfaces are preserved to keep existing code as well as existing
importer implementations working. As Magnum's own importers will get
updated to the new SceneData workflow, a backward compatibility layer
provided that translates it to the subset that the legacy ObjectData
understands.
With this commit, both existing plugin code can build (and test against)
the new workflow, and any ports to the new workflow can test against the
legacy interfaces. Except that for now the compatibility layer doesn't
deal with objects that have more than one mesh or for example a light
and a camera attached, this will be done in a separate step.
Looking at the snippets, these seem to have been written back when there
was no builtin shaders yet, it seems, not to mention
MeshTools::compile(), Trade::MeshData or any of the other high-level
APIs. Rather overwhelming to just throw huge code snippets at the user,
explaining a workflow with a custom-made mesh that's going to be drawn
with a custom-made shader, which is like level 999 of using the GL
library.
It was rather discouraging to start "Basic usage" with a boring-ass long
snippet. On the other hand showing just compile() first would lead
people to think it's all some opaque magic, so trying to balance that a
bit.
Also why the hell was the compile() snippet showing the horrendous GL
way of specifying attribute formats? This is not great either but at
least not redundant.
Using openMemory() instead of openData() allows the implementation to
assume the data will stay in scope for as long as needed, which can
prevent unnecessary copies in some plugin implementations.
It warranted a new flag, DataFlag::ExternallyOwned, to describe this
kind of memory. I couldn't reuse Owned as that's used for allocations
owned by the instance, which is too little for certain future use cases.
For example returning *Data instances referencing an Owned memory would
mean the user has to assume the memory is gone when the importer
instance is gone, and that's generally not true for memory passed to
openMemory().
Originally I thought I would do this later, but then realized the
existing plugin implementations would need to get all updated again to
be aware of the new flag, with some being forgotten, and it's just
easier to do the whole thing in a single step.
Vladimír Vondruš