This renames the set_filters and set_wrap_mode_parameters texture
virtual functions to gl_flush_legacy_texobj_filters and
gl_flush_legacy_texobj_wrap_modes respectively to clarify that they are
opengl driver specific and that they are only used to support the legacy
opengl apis for setting filters and wrap modes where the state is
associated with texture objects instead of being associated with sampler
objects.
This part of an effort to clearly delimit our abstraction over opengl so
that we can start to consider non-opengl backends for Cogl.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 6f78b8a613340d7c6b736e51a16c625f52154430)
Although we use GLib internally in Cogl we would rather not leak GLib
api through Cogl's own api, except through explicitly namespaced
cogl_glib_ / cogl_gtype_ feature apis.
One of the benefits we see to not leaking GLib through Cogl's public API
is that documentation for Cogl won't need to first introduce the Glib
API to newcomers, thus hopefully lowering the barrier to learning Cogl.
This patch provides a Cogl specific typedef for reporting runtime errors
which by no coincidence matches the typedef for GError exactly. If Cogl
is built with --enable-glib (default) then developers can even safely
assume that a CoglError is a GError under the hood.
This patch also enforces a consistent policy for when NULL is passed as
an error argument and an error is thrown. In this case we log the error
and abort the application, instead of silently ignoring it. In common
cases where nothing has been implemented to handle a particular error
and/or where applications are just printing the error and aborting
themselves then this saves some typing. This also seems more consistent
with language based exceptions which usually cause a program to abort if
they are not explicitly caught (which passing a non-NULL error signifies
in this case)
Since this policy for NULL error pointers is stricter than the standard
GError convention, there is a clear note in the documentation to warn
developers that are used to using the GError api.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit b068d5ea09ab32c37e8c965fc8582c85d1b2db46)
Note: Since we can't change the Cogl 1.x api the patch was changed to
not rename _error_quark() functions to be _error_domain() functions and
although it's a bit ugly, instead of providing our own CoglError type
that's compatible with GError we simply #define CoglError to GError
unless Cogl is built with glib disabled.
Note: this patch does technically introduce an API break since it drops
the cogl_error_get_type() symbol generated by glib-mkenum (Since the
CoglError enum was replaced by a CoglSystemError enum) but for now we
are assuming that this will not affect anyone currently using the Cogl
API. If this does turn out to be a problem in practice then we would be
able to fix this my manually copying an implementation of
cogl_error_get_type() generated by glib-mkenum into a compatibility
source file and we could also define the original COGL_ERROR_ enums for
compatibility too.
Note: another minor concern with cherry-picking this patch to the 1.14
branch is that an api scanner would be lead to believe that some APIs
have changed, and for example the gobject-introspection parser which
understands the semantics of GError will not understand the semantics of
CoglError. We expect most people that have tried to use
gobject-introspection with Cogl already understand though that it is not
well suited to generating bindings of the Cogl api anyway and we aren't
aware or anyone depending on such bindings for apis involving GErrors.
(GnomeShell only makes very-very minimal use of Cogl via the gjs
bindings for the cogl_rectangle and cogl_color apis.)
The main reason we have cherry-picked this patch to the 1.14 branch
even given the above concerns is that without it it would become very
awkward for us to cherry-pick other beneficial patches from master.
As part of our on-going goal to remove our dependence on a global Cogl
context this patch adds a pointer to the context to each CoglTexture
so that the various texture apis no longer need to use
_COGL_GET_CONTEXT.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 83131072eea395f18ab0525ea2446f443a6033b1)
The coding style has for a long time said to avoid using redundant glib
data types such as gint or gchar etc because we feel that they make the
code look unnecessarily foreign to developers coming from outside of the
Gnome developer community.
Note: When we tried to find the historical rationale for the types we
just found that they were apparently only added for consistent syntax
highlighting which didn't seem that compelling.
Up until now we have been continuing to use some of the platform
specific type such as gint{8,16,32,64} and gsize but this patch switches
us over to using the standard c99 equivalents instead so we can further
ensure that our code looks familiar to the widest range of C developers
who might potentially contribute to Cogl.
So instead of using the gint{8,16,32,64} and guint{8,16,32,64} types this
switches all Cogl code to instead use the int{8,16,32,64}_t and
uint{8,16,32,64}_t c99 types instead.
Instead of gsize we now use size_t
For now we are not going to use the c99 _Bool type and instead we have
introduced a new CoglBool type to use instead of gboolean.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 5967dad2400d32ca6319cef6cb572e81bf2c15f0)
Removing CoglHandle has been an on going goal for quite a long time now
and finally this patch removes the last remaining uses of the CoglHandle
type and the cogl_handle_ apis.
Since the big remaining users of CoglHandle were the cogl_program_ and
cogl_shader_ apis which have replaced with the CoglSnippets api this
patch removes both of these apis.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 6ed3aaf4be21d605a1ed3176b3ea825933f85cf0)
Since the original patch was done after removing deprecated API
this back ported patch doesn't affect deprecated API and so
actually this cherry-pick doesn't remove all remaining use of
CoglHandle as it did for the master branch of Cogl.
This adds public constructors which take a CoglBitmap to all primitive
texture types. This constructor should be considered the canonical
constructor for initializing the texture with data because it should
be possible to wrap any type of data in a CoglBitmap. Having at least
this single constructor avoids the need to have an explosion of
constructors such as new_from_data, new_from_pixel_buffer and
new_from_file etc.
The already available internal bitmap constructor for CoglTexture2D
has had its flags parameter removed under the assumption that flags do
not make sense for primitive textures. The meta constructor
cogl_texture_new_from_bitmap now just explicitly calls set_auto_mipmap
after constructing the texture depending on the value of the
COGL_TEXTURE_NO_AUTO_MIPMAP flag.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
This interface represents any textures that are backed by a single
texture in GL and that can be used directly with the
cogl_framebuffer_draw_attributes family of functions. This currently
equates to CoglTexture2D, CoglTexture3D and CoglTextureRectangle.
The interface currently has only one method called
cogl_primitive_set_auto_mipmap. This replaces the
COGL_TEXTURE_NO_AUTO_MIPMAP flag from the CoglTextureFlags parameter
in the constructors. None of the other flags in CoglTextureFlags make
sense for primitive textures so it doesn't seem like a good idea to
need them for primitive constructors.
There is a boolean in the vtable to mark whether a texture type is
primitive which the new cogl_is_primitive function uses. There is also
a new texture virtual called set_auto_mipmap which is only required to
be implemented for primitive textures.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
This adds a context member to CoglBitmap which stores the context it
was created with. That way it can be used in texture constructors
which use a bitmap. There is also an internal private function to get
the context out of the bitmap which all of the texture constructors
now use. _cogl_texture_3d_new_from_bitmap has had its context
parameter removed so that it more closely matches the other bitmap
constructors.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Cogl already had a vtable for the texture driver. This ended up being
used for some things that are not strictly related to texturing such
as converting between pixel formats and GL enums. Some other functions
that are driver dependent such as updating the features were not
indirected through a vtable but instead switched directly by looking
at the ctx->driver enum value. This patch normalises to the two uses
by adding a separate vtable for driver functions not related to
texturing and moves the pixel format conversion functions to it from
the texture driver vtable. It also adds a context parameter to all of
the functions in the new driver vtable so that they won't have to rely
on the global context.
This creates a CoglBitmap which points into an existing buffer in
system memory. That way it can be used to create a texture or to read
pixel data into. The function replaces the existing internal function
_cogl_bitmap_new_from_data but removes the destroy notify call back.
If the application wants notification of destruction it can just use
the cogl_object_set_user_data function as normal. Internally there is
now a convenience function to create a bitmap for system memory and
automatically free the buffer using that mechanism.
The name of the function is inspired by
cairo_image_surface_create_for_data which has similar semantics.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
This option to GCC makes it give a warning whenever a global function
is defined without a declaration. This should catch cases were we've
defined a function but forgot to put it in a header. In that case it
is either only used within one file so we should make it static or we
should declare it in a header.
The following changes where made to fix problems:
• Some functions were made static
• cogl-path.h (the one containing the 1.0 API) was split into two
files, one defining the functions and one defining the enums so that
cogl-path.c can include the enum and function declarations from the
2.0 API as well as the function declarations from the 1.0 API.
• cogl2-clip-state has been removed. This only had one experimental
function called cogl_clip_push_from_path but as this is unstable we
might as well remove it favour of the equivalent cogl_framebuffer_*
API.
• The GLX, SDL and WGL winsys's now have a private header to define
their get_vtable function instead of directly declaring in the C
file where it is called.
• All places that were calling COGL_OBJECT_DEFINE need to have the
cogl_is_whatever function declared so these have been added either
as a public function or in a private header.
• Some files that were not including the header containing their
function declarations have been fixed to do so.
• Any unused error quark functions have been removed. If we later want
them we should add them back one by one and add a declaration for
them in a header.
• _cogl_is_framebuffer has been renamed to cogl_is_framebuffer and
made a public function with a declaration in cogl-framebuffer.h
• Similarly for CoglOnscreen.
• cogl_vdraw_indexed_attributes is called
cogl_framebuffer_vdraw_indexed_attributes in the header. The
definition has been changed to match the header.
• cogl_index_buffer_allocate has been removed. This had no declaration
and I'm not sure what it's supposed to do.
• CoglJournal has been changed to use the internal CoglObject macro so
that it won't define an exported cogl_is_journal symbol.
• The _cogl_blah_pointer_from_handle functions have been removed.
CoglHandle isn't used much anymore anyway and in the few places
where it is used I think it's safe to just use the implicit cast
from void* to the right type.
• The test-utils.h header for the conformance tests explicitly
disables the -Wmissing-declaration option using a pragma because all
of the tests declare their main function without a header. Any
mistakes relating to missing declarations aren't really important
for the tests.
• cogl_quaternion_init_from_quaternion and init_from_matrix have been
given declarations in cogl-quaternion.h
Reviewed-by: Robert Bragg <robert@linux.intel.com>
We are in the process of removing all _EXP suffix mangling for
experimental APIs (Ref: c6528c4b6c) and adding missing gtk-doc
comments so that we can instead rely on the "Stability: unstable"
markers in the gtk-doc comments. This patch tackles the cogl-texture-3d
api symbols.
This patch also replaces use of CoglHandle with a CoglTexture3D type
instead.
Finally this patch also ensures the CoglTexture3D constructors take an
explicit CoglContext pointer but not a CoglTextureFlags argument,
consistent with other CoglTexture constructors.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
The cogl.h header is meant to be the public header for including the 1.x
api used by Clutter so we should stop using that as a convenient way to
include all likely prototypes and typedefs. Actually we already do a
good job of listing the specific headers we depend on in each of the .c
files we have so mostly this patch just strip out the redundant
includes for cogl.h with a few fixups where that broke the build.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
This moves _cogl_get_format_bpp from cogl-bitmap.c to cogl.c and renames
it to _cogl_pixel_format_get_bytes_per_pixel. This makes it clearer that
it doesn't return bits per pixel and makes the naming consistent with
other cogl api. The prototype has been moved to cogl-private.h since it
seems we should be aiming to get rid of cogl-internal.h at some point.
The patch also adds a simple gtk-doc comment since we might want to make
this api public.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
This adds an internal function to get the type of the underlying
hardware texture for any CoglTexture. It can return one of three
values to represent 2D textures, 3D textures or rectangle textures.
The idea is that this can be used as a replacement for
cogl_texture_get_gl_texture when only the target is required to make
it a bit less GL-centric. The implementation adds a new virtual
function which all of the texture backends now implement.
The enum is in a public header because a later patch will want to use
it from the CoglPipeline API. We may want to consider making the
function public too later.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Since we've had several developers from admirable projects say they
would like to use Cogl but would really prefer not to pull in
gobject,gmodule and glib as extra dependencies we are investigating if
we can get to the point where glib is only an optional dependency.
Actually we feel like we only make minimal use of glib anyway, so it may
well be quite straightforward to achieve this.
This adds a --disable-glib configure option that can be used to disable
features that depend on glib.
Actually --disable-glib doesn't strictly disable glib at this point
because it's more helpful if cogl continues to build as we make
incremental progress towards this.
The first use of glib that this patch tackles is the use of
g_return_val_if_fail and g_return_if_fail which have been replaced with
equivalent _COGL_RETURN_VAL_IF_FAIL and _COGL_RETURN_IF_FAIL macros.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
CoglMetaTexture is an interface for dealing with high level textures
that may be comprised of one or more low-level textures internally. The
interface allows the development of primitive drawing APIs that can draw
with high-level textures (such as atlas textures) even though the
GPU doesn't natively understand these texture types.
There is currently just one function that's part of this interface:
cogl_meta_texture_foreach_in_region() which allows an application to
resolve the internal, low-level textures of a high-level texture.
cogl_rectangle() uses this API for example so that it can easily emulate
the _REPEAT wrap mode for textures that the hardware can't natively
handle repeating of.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
Currently features are represented as bits in a 32bit mask so we
obviously can't have more than 32 features with that approach. The new
approach is to use the COGL_FLAGS_ macros which lets us handle bitmasks
without a size limit and we change the public api to accept individual
feature enums instead of a mask. This way there is no limit on the
number of features we can add to Cogl.
Instead of using cogl_features_available() there is a new
cogl_has_feature() function and for checking multiple features there is
cogl_has_features() which takes a zero terminated vararg list of
features.
In addition to being able to check for individual features this also
adds a way to query all the features currently available via
cogl_foreach_feature() which will call a callback for each feature.
Since the new functions take an explicit context pointer there is also
no longer any ambiguity over when users can first start to query
features.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
The GL or GLES library is now dynamically loaded by the CoglRenderer
so that it can choose between GL, GLES1 and GLES2 at runtime. The
library is loaded by the renderer because it needs to be done before
calling eglInitialize. There is a new environment variable called
COGL_DRIVER to choose between gl, gles1 or gles2.
The #ifdefs for HAVE_COGL_GL, HAVE_COGL_GLES and HAVE_COGL_GLES2 have
been changed so that they don't assume the ifdefs are mutually
exclusive. They haven't been removed entirely so that it's possible to
compile the GLES backends without the the enums from the GL headers.
When using GLX the winsys additionally dynamically loads libGL because
that also contains the GLX API. It can't be linked in directly because
that would probably conflict with the GLES API if the EGL is
selected. When compiling with EGL support the library links directly
to libEGL because it doesn't contain any GL API so it shouldn't have
any conflicts.
When building for WGL or OSX Cogl still directly links against the GL
API so there is a #define in config.h so that Cogl won't try to dlopen
the library.
Cogl-pango previously had a #ifdef to detect when the GL backend is
used so that it can sneakily pass GL_QUADS to
cogl_vertex_buffer_draw. This is now changed so that it queries the
CoglContext for the backend. However to get this to work Cogl now
needs to export the _cogl_context_get_default symbol and cogl-pango
needs some extra -I flags to so that it can include
cogl-context-private.h
The texture driver functions are now accessed through a vtable pointed
to by a struct in the CoglContext so that eventually it will be
possible to compile both the GL and GLES texture drivers into a single
binary and then select between them at runtime.
cogl-ext-functions.h now contains definitions for all of the core GL
and GLES functions that we would normally link to directly. All of the
code has changed to access them through the cogl context pointer. The
GE macro now takes an extra parameter to specify the context because
the macro itself needs to make GL calls but various points in the Cogl
source use different names for the context variable.
Instead of storing all of the feature function pointers in the driver
specific data of the CoglContext they are now all stored directly in
CoglContext. There is a single header containing the description of
the functions which gets included by cogl-context.h. There is a single
function in cogl-feature-private.c to check for all of these
functions.
The name of the function pointer variables have been changed from
ctx->drv.pf_glWhatever to just ctx->glWhatever.
The feature flags that get set when an extension is available are now
separated from the table of extensions. This is necessary because
different extensions can mean different things on GLES and GL. For
example, having access to glMapBuffer implies read and write support
on GL but only write support on GLES. The flags are instead set in the
driver specific init function by checking whether the function
pointers were successfully resolved.
_cogl_feature_check has been changed to assume the feature is
supported if any of the listed extensions are available instead of
requiring all of them. This makes it more convenient to specify
alternate names for the extension. Nothing else had previously listed
more than one name for an extension so this shouldn't cause any
problems.
Instead of having a single journal per context, we now have a
CoglJournal object for each CoglFramebuffer. This means we now don't
have to flush the journal when switching/pushing/popping between
different framebuffers so for example a Clutter scene that involves some
ClutterEffect actors that transiently redirect to an FBO can still be
batched.
This also allows us to track state in the journal that relates to the
current frame of its associated framebuffer which we'll need for our
optimization for using the CPU to handle reading a single pixel back
from a framebuffer when we know the whole scene is currently comprised
of simple rectangles in a journal.
The GLES2 wrapper is no longer needed because the shader generation is
done within the GLSL fragend and vertend and any functions that are
different for GLES2 are now guarded by #ifdefs.
There's no longer any need to use the GL handle in the callback for
_cogl_texture_foreach_sub_texture_in_region because it can now work in
terms of primitive cogl textures so it has now been removed. This
would be helpful if we ever want to make the foreach function public
so that apps could implement their own primitives using sliced
textures.
This applies an API naming change that's been deliberated over for a
while now which is to rename CoglMaterial to CoglPipeline.
For now the new pipeline API is marked as experimental and public
headers continue to talk about materials not pipelines. The CoglMaterial
API is now maintained in terms of the cogl_pipeline API internally.
Currently this API is targeting Cogl 2.0 so we will have time to
integrate it properly with other upcoming Cogl 2.0 work.
The basic reasons for the rename are:
- That the term "material" implies to many people that they are
constrained to fragment processing; perhaps as some kind of high-level
texture abstraction.
- In Clutter they get exposed by ClutterTexture actors which may be
re-inforcing this misconception.
- When comparing how other frameworks use the term material, a material
sometimes describes a multi-pass fragment processing technique which
isn't the case in Cogl.
- In code, "CoglPipeline" will hopefully be a much more self documenting
summary of what these objects represent; a full GPU pipeline
configuration including, for example, vertex processing, fragment
processing and blending.
- When considering the API documentation story, at some point we need a
document introducing developers to how the "GPU pipeline" works so it
should become intuitive that CoglPipeline maps back to that
description of the GPU pipeline.
- This is consistent in terminology and concept to OpenGL 4's new
pipeline object which is a container for program objects.
Note: The cogl-material.[ch] files have been renamed to
cogl-material-compat.[ch] because otherwise git doesn't seem to treat
the change as a moving the old cogl-material.c->cogl-pipeline.c and so
we loose all our git-blame history.
When building with --enable-profile we now depend on the uprof-0.3
developer release which brings a few improvements:
» It lets us "fix" how we initialize uprof so that instead of using a shared
object constructor/destructor (which was a hack used when first adding
uprof support to Clutter) we can now initialize as part of clutter's
normal initialization code. As a side note though, I found that the way
Clutter initializes has some quite serious problems whenever it
involves GOptionGroups. It is not able to guarantee the initialization
of dependencies like uprof and Cogl. For this reason we still use the
contructor/destructor approach to initialize uprof in Cogl.
» uprof-0.3 provides a better API for adding custom columns when reporting
timer and counter statistics which lets us remove quite a lot of manual
report generation code in clutter-profile.c.
» uprof-0.3 provides a shared context for tracking mainloop timer
statistics. This means any mainloop based library following the same
"Mainloop" timer naming convention can use the shared context and no
matter who ends up owning the final mainloop the statistics will always
be in the same place. This allows profiling of Clutter with an
external mainloop such as with the Mutter compositor.
» uprof-0.3 can export statistics over dbus and comes with an ncurses
based ui to vizualize timer and counter stats live.
The latest version of uprof can be cloned from:
git://github.com/rib/UProf.git
The CoglBitmap struct is now only defined within cogl-bitmap.c so that
all of its members can now only be accessed with accessor
functions. To get to the data pointer for the bitmap image you must
first call _cogl_bitmap_map and later call _cogl_bitmap_unmap. The map
function takes the same arguments as cogl_pixel_array_map so that
eventually we can make a bitmap optionally internally divert to a
pixel array.
There is a _cogl_bitmap_new_from_data function which constructs a new
bitmap object and takes ownership of the data pointer. The function
gets passed a destroy callback which gets called when the bitmap is
freed. This is similar to how gdk_pixbuf_new_from_data
works. Alternatively NULL can be passed for the destroy function which
means that the caller will manage the life of the pointer (but must
guarantee that it stays alive at least until the bitmap is
freed). This mechanism is used instead of the old approach of creating
a CoglBitmap struct on the stack and manually filling in the
members. It could also later be used to create a CoglBitmap that owns
a GdkPixbuf ref so that we don't necessarily have to copy the
GdkPixbuf data when converting to a bitmap.
There is also _cogl_bitmap_new_shared. This creates a bitmap using a
reference to another CoglBitmap for the data. This is a bit of a hack
but it is needed by the atlas texture backend which wants to divert
the set_region virtual to another texture but it needs to override the
format of the bitmap to ignore the premult flag.
glTexSubImage3D was being called directly in cogl-texture-3d.c but the
function is only available since GL version 1.2 so on Windows it won't
be possible to directly link to it. Also under GLES it is only
available conditionally in an extension.
In ddb9016be4 the texture backends were changed to include
cogl-material-opengl-private.h instead of cogl-material-private.h.
However the 3D texture backend was missed from this so it was giving a
compiler warning about using an undeclared function.
The CoglTexture2DSliced backend has a fallback for when the
framebuffer extension is missing so it's not possible to use
glGenerateMipmap. This involves keeping a copy of the upper-left pixel
of the tex image so that we can temporarily enable GL_GENERATE_MIPMAP
on the texture object and do a sub texture update by reuploading the
contents of the first pixel. This patch copies that mechanism to the
2D and 3D backends. The CoglTexturePixel structure which was
previously internal to the sliced backend has been moved to
cogl-texture-private.h so that it can be shared.
Using 'r' to name the third component is problematic because that is
commonly used to represent the red component of a vector representing
a color. Under GLSL this is awkward because the texture swizzling for
a vector uses a single letter for each component and the names for
colors, textures and positions are synonymous. GLSL works around this
by naming the components of the texture s, t, p and q. Cogl already
effectively already exposes this naming because it exposes GLSL so it
makes sense to use that naming consistently. Another alternative could
be u, v and w. This is what Blender and Direct3D use. However the w
component conflicts with the w component of a position vertex.
This adds a publicly exposed experimental API for a 3D texture
backend. There is a feature flag which can be checked for whether 3D
textures are supported. Although we require OpenGL 1.2 which has 3D
textures in core, GLES only provides them through an extension so the
feature can be used to detect that.
The textures can be created with one of two new API functions :-
cogl_texture_3d_new_with_size
and
cogl_texture_3d_new_from_data
There is also internally a new_from_bitmap function. new_from_data is
implemented in terms of this function.
The two constructors are effectively the only way to upload data to a
3D texture. It does not work to call glTexImage2D with the
GL_TEXTURE_3D target so the virtual for cogl_texture_set_region does
nothing. It would be possible to make cogl_texture_get_data do
something sensible like returning all of the images as a single long
image but this is not currently implemented and instead the virtual
just always fails. We may want to add API specific to the 3D texture
backend to get and set a sub region of the texture.
All of those three functions can throw a GError. This will happen if
the GPU does not support 3D textures or it does not support NPOTs and
an NPOT size is requested. It will also fail if the FBO extension is
not supported and the COGL_TEXTURE_NO_AUTO_MIPMAP flag is not
given. This could be avoided by copying the code for the
GL_GENERATE_MIPMAP TexParameter fallback, but in the interests of
keeping the code simple this is not yet done.
This adds a couple of functions to cogl-texture-driver for uploading
3D data and querying the 3D proxy
texture. prep_gl_for_pixels_upload_full now also takes sets the
GL_UNPACK_IMAGE_HEIGHT parameter so that 3D textures can have padding
between the images. Whenever 3D texture is uploading, both the height
of the images and the height of all of the data is specified (either
explicitly or implicilty from the CoglBitmap) so that the image height
can be deduced by dividing by the depth.
