In OpenGL ES 2.0 there is EXT_draw_buffers, which I overlooked somehow,
so I added it to extension list and included in the implementation. It
combines NV_draw_buffers and NV_fbo_color_attachments, so the
implementation now selects one of the two based on which extension is
supported, preferring the EXT one. Updated the documentation to be
less confusing, fixed extension links. Also the single-output
mapForDraw() is not handled separately on ES anymore and just calls
DrawBuffers implementation with single parameter, resulting in less
generated code.
EXT_draw_buffers can also be called on default framebuffer and
apparently in ES there is no way to map front framebuffer for drawing,
so I removed it from the DefaultFramebuffer::DrawAttachment enum.
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.
According to reports on delphigl.de this extension is far more supported
in comparison to the NV version (and also there's much less FF cruft in
the specification).
In OpenGL ES this is implemented in EXT_multi_draw_arrays extension, if
it is not available, the functionality is emulated using sequence of
normal draw() calls.
Functionality provided by GL 3.3 and ARB_instanced_arrays, on ES2 this
is again implemented in three different extensions --
{ANGLE,EXT,NV}_instanced_arrays. They are disabled until Magnum has
proper extension loading on ES.
On desktop GL this is provided by ARB_draw_instanced (GL 3.1). Base
instance is available only on desktop GL (4.2, ARB_base_instance). In
ES2 the instanced functionality is provided by three (!) different
extensions (ANGLE_instanced_arrays, EXT_draw_instanced,
NV_draw_instanced), the proper implementation is chosen on context
creation based on what extension is available. Though we don't have
extension loader for ES yet, thus all these extensions are disabled and
the implementation has assertion in it.
Added blind test which tests only that something has been drawn and no
errors were emitted, but not whether the right command is used. I'll
probably need to check this later, because the Mesh::draw() behemoth is
going slightly out of hand :)
I didn't yet have time to add more complete support for ES 3.1, but the
engine should at least work on it. If the driver reports ES 3.0 or 3.1
it is taken as valid value in both ES2 and ES3 builds (i.e. the engine
can work in ES2 mode also on ES3 driver).
Returns list of _all_ extensions reported by the driver, even those that
are not supported in Magnum and also those that are marked as disabled
due to driver bugs. Usable mostly when doing fresh port to new platform
to discover possible new features.
The actual implementation was part of Context constructor (and now this
function is called instead). It is rather ugly because we need to take
care of both GL 2.1 and GL 3.0 (and also ES2 and ES3).
Make it less annoying to debug things on platforms which send all
standard output to /dev/hell without any easy way to override that. Yes,
I'm looking at you, Android.
There is no ES 2.5 or 3.01 and this way we can properly check for
garbage returned by `glGet(GL_VERSION_M*OR)` (e.g. version 2674.-2O8539
would pass here).
Previously the extensions were either disabled altogether (e.g. because
we don't have yet extension wrangler on ES) or had manually adjusted
minimal required versions to avoid issues on older versions (e.g.
ARB_explicit_attrib_location is known to give compiler errors when used
with GLSL < 1.50 on some drivers), both done basically at compile time
unrelated to actual hardware/driver used.
Now all the extensions are enabled exactly as the driver advertises them
(or when their core version is not larger than the context version) and
have minimal required versions as per specification. Given extension is
supported in given version when it is marked as such and its minimal
required version is not larger than the requested one. The extension
disabling is thus done by simply increasing the minimal required version
to larger value (or Version::None for disabling it for all versions).
Currently no such disabling is put into place, but the existing
workarounds scattered all over the place will be gradually converted to
this.
Simplified the code and tests by marking all extensions from previous
versions as supported instead of additional "shorthand" checking whether
extension's core version is supported. The check wasn't probably much of
a speedup, as it was just another branch. This was also buggy
previously, because when the extension would be reported as not being
supported in older versions, which is not what we want. Hopefully this
won't reintroduce the numerous issues with Mesa and OSX I had in the
past :-)
Also removed duplicate implementation of
Context::isExtensionSupported(), one overload is now calling the other.
Both don't have GL_{MAJOR,MINOR}_VERSION enums so we must decide whether
the version is older than OpenGL 3.0 / ES 3.0 either using
MAGNUM_TARGET_GLES2 preprocessor definition or checking for invalid enum
error and then we have to parse version string to ensure that the
version is not too old. On ES2 the version check wasn't present at all
(only optimistic hope), this makes it more hardened.
Vladimír Vondruš