Since the main point of the low-level API is to make use of the
EXT_multi_draw_arrays / ANGLE_multi_draw / WEBGL_multi_draw extensions
for a reduced driver overhead *and* the builtin gl_DrawID variable, it
just doesn't make sense to provide a fallback to draw() in a loop. When
the extensions are not available, the user has to do extra work in order
to supply proper UBO draw offset for each draw call, and thus the
fallback path has basically no practical use.
On the other hand, draw() taking the MeshView instances is kept as-is --
this one is rather old and so breaking compatibility would be an
unnecessary pain point. Plus, since it has to allocate the contiguous
arrays internally, it's not desirable for any fast-path rendering
anyway.
Because a MeshView might not be the best thing to have when you are
submitting a batch of thousand draws. It takes a strided array views to
allow for more flexibility, but can also detect if the input is already
contiguous and use it as-is.
UNFORTUNATELY the GL 1.0 legacy still continues to stink and so there
has to be a 64-bit-specific overload which is the *actual* variant that
doesn't allocate because glMultiDrawElements takes a `void**` for INDEX
OFFSETS and it's IN BYTES! Which foolish soul designed such a thing back
in the 1860s, I wonder. There's no reason to not have an index offset
in elements because all indices have to have the same type ANYWAY. And
yes, I wasted about three hours debugging driver crashes because I
THOUGHT this parameter takes offset in elements, not bytes.
Also note: on 32-bit platforms this depends on latest Corrade with the
CORRADE_TARGET_32BIT definition. Spent an embarrassing amount of time
wondering why all local builds but Emscripten work.
There are no SSO / DSA extensions on that platform, so it doesn't make
sense to do this extra indirection. Saves another kilobyte (237 -> 236
kB) in WebGL 2 magnum-gl-info.wasm.
Instead of wrapping glProgramUniform*() inside a member function, we now
call that function directly, which allows us to remove 2/3rds of
AbstractShaderProgram members. The non-DSA code path is still
implemented though member functions, though they are now static,
mimic the signature of the DSA APIs and do a use() + glUniform*()
internally.
This means that instead of 12 separate allocations we have just one,
allocating everything together in a contiguous piece of memory. That
should be also a bit more cache friendly when accessing the state as
it's not scattered around the memory like crazy.
Because there are no Pointer indirections needed anymore, the State
members are just references now. That resulted in a lot of sweeping
changes around the whole GL library, but they're all trivial, changing
`->` to `.`, mostly.
There's two more nested allocations in the TextureState struct, will
take care of them in a separate commit.
This was done silently until now and I think such platform-specific code
should be always exposed as a disableable workaround. Moreover, I need a
similar thing for ANGLE, so this comes handy.
As usual, the old APIs are still present, but marked as deprecated.
Existing code is not updated yet to ensure I didn't break anything with
this.
This way it's much more intuitive and makes the code shorter and nicer
in many cases. Shaders are now also able to hide irrelevant
draw/dispatch APIs to avoid accidents.
What's left is *a lot* of places taking monstrous
std::vector<std::reference_wrapper> and that can't be changed to
std::vector<Containers::Reference> in a source-compatible way. Even that
would be only a temporary change, since the goal is to fully avoid
dependency on STL in those cases.
The final version of these APIs should take
Containers::ArrayView<Containers::Reference> and be implicitly
convertible froom e.g. std::vector<Containers::Reference>. That's
definitely possible, but not in time for 2019.01, so instead of forcing
users to temporary pass a `{vec.begin(), vec.size()}` everywhere instead
of just `vec`, I'm rather keeping these APIs intact.
Was Magnum::GL::Extensions::GL before and the redundancy was completely
unnecessary. Potential future extensions coming from GLX, EGL or whatnot
will most probably be in the Platform namespace in a completely separate
file, so this is not a problem.
All code internal to the GL library is affected, not much the outside,
as that is handled by the compatibility alias.
At the moment just the GL library itself w/o the tests, and without
backwards compatibility aliases. The following types were left in the
root namespace, despite being in the GL/ directory, as they will get
moved back soon:
* Image, CompressedImage and their dimensional typedefs
* ImageView, CompressedImageView and their dimensional typedefs
* PixelStorage
Not PixelFormat etc., that one will stay in the GL namespace and a
completely new PixelFormat enum will be provided in the root namespace.
Minimal updates (just the include guards) so Git is hopefully able to
detect the rename and track the history properly.
Everything except Magnum::GL doesn't compile now.
On Windows NVidia drivers the glTransformFeedbackVaryings() does not
make a copy of its char* arguments so it fails at link time when the
original char arrays are not in scope anymore. Enabling *synchronous*
debug output circumvents this bug. Can be triggered by running
TransformFeedbackGLTest with GL_KHR_debug extension disabled.
103% of use cases use the returned value directly without checking, so
we might as well do the check ourselves. Added new function hasCurrent()
and added deprecated backward-compatibility conversion and -> operators.
Wow, that creeped to a lot of places.
Last dinosaur from the pointer age.
The previous AbstractShaderProgram::setUniform(Int, UnsignedInt, T*)
function is now alias to the new one, is marked as deprecated and will
be removed in some future release.
Intel drivers on Windows print out "No errors." when the shader is
compiled/linked successfully. I consider that as unnecessary spam and
filter it out.
Full support for EXT_transform_feedback, transform feedback objects
from ARB_transform_feedback2 and equivalent OpenGL ES 3.0 functionality.
Example usage is in src/Magnum/Test/TransformFeedbackGLTest.cpp, I'll
add some example later.
No backward compatibility issues should exist, as the class is in most
(if not all) cases used with unscoped name:
class MyShader: public AbstractShaderProgram {
public:
typedef Attribute<0, Vector3> Position;
// ...
};
Vladimír Vondruš