* Half-floats and floats are usable in ES2 / WebGL 1 (they weren't by
mistake) -- just use OES_texture_float or OES_texture_half_float.
* Half-floats are linearly filterable in ES3 / WebGL 2 and
OES_texture_half_float_linear makes it possible in ES2 / WebGL 1.
* Floats are not linearly filterable, not even in ES3 (they were by
mistake) -- one needs OES_texture_float_linear for that.
* Neither floats nor half-floats are renderable in ES < 3.2 -- one
needs EXT_color_buffer_half_float or EXT_color_buffer_float for that.
The former is available for example on iOS, the latter is apparently
only on NV cards. Both are builtin in ES 3.2, EXT_color_buffer_float
depends in ES3, so half-floats are the only possible format to render
to in ES2.
* Rendering to floats in WebGL is slightly more complicated --
unlike with OpenGL ES 2 it's possible to render to floats in WebGL 1
using WEBGL_color_buffer_float. There's another WebGL 1 extension
called EXT_color_buffer_half_float and they are both replaced with
EXT_color_buffer_float in WebGL 2.
And, as a cherry on top, GPH (formerly SGI) has patents on most of
these, which is probably why the support for them is so spotty.
Since 98a676ef65, on ES2 and WebGL1 the
Texture::setStorage() emulation passes the pixel format to both <format>
and <internalFormat> of glTexImage() APIs. On desktop the go-to way to
create a sRGB texture is by passing GL_SRGB to <internalFormat> and
GL_RGB to <format>, but here GL_RGB was passed to both and thus the
information about sRGB was lost.
With the new PixelFormat::SRGB and PixelFormat::SRGBAlpha enums that
are present only on ES2/WebGL1 this case is fixed -- sRGB texture format
will get translated to sRGB pixel format and that used for both
<format> and <internalFormat>.
Another case is when EXT_texture_storage is available -- passing unsized
GL_SRGB_EXT or GL_SRGB_ALPHA_EXT to glTexStorageEXT() is an error and
there's apparently no mention of this in any extension, making it
impossible to create sRGB textures using EXT_texture_storage. I bit the
bullet and tried passing the (numerical value of) GL_SRGB8 and
GL_SRGB8_ALPHA8 to it. At least on my NV it worked, so I enabled these
two in TextureFormat for ES2. No EXT_texture_storage is on WebGL1, so
they are only on ES2.
These two sized TextureFormat::SRGB8 and TextureFormat::SRGB8Alpha8
formats are translated to GL_SRGB and GL_SRGB_ALPHA and so using them
unconditionally for all platforms (except WebGL1) "just works".
Followup to previous commit -- links to opengl.org are now redirected to
khronos.org and the extension links have the same format for both GL and
GLES. That allows me to remove some of the Doxygen aliases and use just
a single set of the functions for both GL and GLES.
Most of the code is in the actual test where I'm comparing and
benchmarking three different implementations (a
naive/straightforward/ground-truth one, the chosen one and a fast though
cache-spilling table-based one) to ensure the behavior is consistent
across all of them and that the performance is within reasonable bounds.
The Corrade::TestSuite benchmarking stuff needs serious improvements,
though.
Yeah, sorry, I know, the enums are renamed for second or third time in a
row, first they were Image::Format, then ImageFormat, then ColorFormat
and now PixelFormat. But this time it's final and last time they are
renamed and now everything is finally consistent:
* ColorFormat::DepthComponent -- depth is not a color, thus
PixelFormat::DepthComponent makes a lot more sense.
* There will be PixelStorage classes, which will be stored in images
alonside PixelFormat/PixelType enums, making everything nicely
aligned.
* The GL documentation about glTexImage2D() etc. denotes the <format>
and <type> parameters as format and type of *pixel* data, so now we
are _finally_ consistent with the official naming.
I wonder why did I not choose PixelFormat originally. Anyway, the old
<Magnum/ColorFormat.h> header, ColorFormat, ColorType and
CompressedColorFormat types are now aliases to the new ones, are marked
as deprecated and will be removed in some future release (as always, I'm
waiting at least six months before removing the deprecated
functionality).
It is superseded by core functionality. The only annoyance is that you
need to use TextureFormat::SRGB in ES2 and TextureFormat::SRGB8 in ES3,
but that's with many other formats anyway. Also apparently the unsized
format is still allowed in core desktop GL, which is a shame.
It makes sense, but this ordering also helps to avoid bug in Doxygen
1.8.6+ which merges next non-xrefitem section with the previous one (so
e.g. the TODO list contained the following @see block, which is not
desired).
The only places where they aren't absolute are:
- when header is included from corresponding source file
- when including headers which are not part of final installation (e.g.
test-specific configuration, headers from Implementation/)
Everything what was in src/ is now in src/Corrade, everything from
src/Plugins is now in src/MagnumPlugins, everything from external/ is in
src/MagnumExternal. Added new CMakeLists.txt file and updated the other
ones for the moves, no other change was made. If MAGNUM_BUILD_DEPRECATED
is set, everything compiles and installs like previously except for the
plugins, which are now in MagnumPlugins and not in Magnum/Plugins.
Until recently (or maybe not too recently) ES3 extension header was
"currently empty", now the extension header is shared with ES2. It's
nice to finally get rid of all the weird ifndefs.
Removed all known GLEW workarounds, added one small workaround for
missing ARB_texture_compression_bptc. I didn't want to patch glLoadGen
for just four enum values, this way it's possible to use stock one
without any patching (except for missing OpenGL 2.1 support, as stated
in external/OpenGL/GL/README.md).
As one file now replaces both `glew.h` and `glcorearb.h` and it has the
same size as `glcorearb.h` alone , it saves approximately 18k LOC,
resulting in 15 second shorter compilation time (5:03 before, 4:48 now).
Not bad.
Separated EXT_framebuffer_object, EXT_framebuffer_blit,
EXT_framebuffer_multisample and EXT_packed_depth_stencil don't have the
same functionality as ARB_framebuffer_object (e.g. missing
GL_FRAMEBUFFER_UNDEFINED in glCheckFramebufferStatus()) and separated
read/draw binding is only in EXT_framebuffer_blit, which complicates the
internals.
Checked with Mesa 8/9 and OpenGL 2.1, current one has
ARB_framebuffer_object and also all these four, Mesa 7.7 didn't have
EXT_framebuffer_multisample, but that's a long time ago, so not
supporting these separate extensions shouldn't be an issue.
The problem with unavailable separate binding points remains on OpenGL
ES 2.0, there are three different extensions bringing that
functionality, thus the code managing the available binding points
remains there.
Special RGB values together, RGBA values together, Depth values
together, DepthStencil values together. Left sized internal formats in
the same order, though.
Vladimír Vondruš