Consistent with how we lazily allocate framebuffers this patch allows us
to instantiate textures but still specify constraints and requirements
before allocating storage so that we can be sure to allocate the most
appropriate/efficient storage.
This adds a cogl_texture_allocate() function that is analogous to
cogl_framebuffer_allocate() which can optionally be called to explicitly
allocate storage and catch any errors. If this function isn't used
explicitly then Cogl will implicitly ensure textures are allocated
before the storage is needed.
It is generally recommended to rely on lazy storage allocation or at
least perform explicit allocation as late as possible so Cogl can be
fully informed about the best way to allocate storage.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 1fa7c0f10a8a03043e3c75cb079a49625df098b7)
Note: This reverts the cogl_texture_rectangle_new_with_size API change
that dropped the CoglError argument and keeps the semantics of
allocating the texture immediately. This is because Mutter currently
uses this API so we will probably look at updating this later once
we have a corresponding Mutter patch prepared. The other API changes
were kept since they only affected experimental api.
There was a lot of redundancy in how we tracked the width and height of
different texture types which is greatly simplified by adding width and
height members to CoglTexture directly and removing the get_width and
get_height vfuncs from CoglTextureVtable
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 3236e47723e4287d5e0023f29083521aeffc75dd)
This moves the _cogl_texture_get_gl_format function from cogl-texture.c
to cogl-texture-gl.c and renames it _cogl_texture_gl_get_format.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit f8deec01eff7d8d9900b509048cf1ff1c86ca879)
This remove cogl-internal.h in favour of using cogl-private.h. Some
things in cogl-internal.h were moved to driver/gl/cogl-util-gl-private.h
and the _cogl_gl_error_to_string function whose prototype was moved from
cogl-internal.h to cogl-util-gl-private.h has had its implementation
moved from cogl.c to cogl-util-gl.c
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 01cc82ece091aa3bec4c07fdd6bc9e5135fca573)
cogl_texture_set_region() and cogl_texture_set_region_from_bitmap() now
have a level argument so image data can be uploaded to a specific mipmap
level.
The prototype for cogl_texture_set_region was also updated to simplify
the arguments.
The arguments for cogl_texture_set_region_from_bitmap were reordered to
be consistent with cogl_texture_set_region with the source related
arguments listed first followed by the destination arguments.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 3a336a8adcd406b53731a6de0e7d97ba7932c1a8)
Note: Public API changes were reverted in cherry-picking this patch
This adds a driver/gl/cogl-texture-gl.c file and moves some gl specific
bits from cogl-texture.c into it. The moved symbols were also given a
_gl_ infix and the calling code was updated accordingly.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 2c9e81de70cc02d72b1ce9013c49e39300a05b6a)
This allows apps to catch out-of-memory errors when allocating textures.
Textures can be pretty huge at times and so it's quite possible for an
application to try and allocate more memory than is available. It's also
very possible that the application can take some action in response to
reduce memory pressure (such as freeing up texture caches perhaps) so
we shouldn't just automatically abort like we do for trivial heap
allocations.
These public functions now take a CoglError argument so applications can
catch out of memory errors:
cogl_buffer_map
cogl_buffer_map_range
cogl_buffer_set_data
cogl_framebuffer_read_pixels_into_bitmap
cogl_pixel_buffer_new
cogl_texture_new_from_data
cogl_texture_new_from_bitmap
Note: we've been quite conservative with how many apis we let throw OOM
CoglErrors since we don't really want to put a burdon on developers to
be checking for errors with every cogl api call. So long as there is
some lower level api for apps to use that let them catch OOM errors
for everything necessary that's enough and we don't have to make more
convenient apis more awkward to use.
The main focus is on bitmaps and texture allocations since they
can be particularly large and prone to failing.
A new cogl_attribute_buffer_new_with_size() function has been added in
case developers need to catch OOM errors when allocating attribute buffers
whereby they can first use _buffer_new_with_size() (which doesn't take a
CoglError) followed by cogl_buffer_set_data() which will lazily allocate
the buffer storage and report OOM errors.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit f7735e141ad537a253b02afa2a8238f96340b978)
Note: since we can't break the API for Cogl 1.x then actually the main
purpose of cherry picking this patch is to keep in-line with changes
on the master branch so that we can easily cherry-pick patches.
All the api changes relating stable apis released on the 1.12 branch
have been reverted as part of cherry-picking this patch so this most
just applies all the internal plumbing changes that enable us to
correctly propagate OOM errors.
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)
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 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 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>
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 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>
This exposes cogl_sub_texture_new() and cogl_is_sub_texture() as
experimental public API. Previously sub-textures were only exposed via
cogl_texture_new_from_sub_texture() so there wasn't a corresponding
CoglSubTexture type. A CoglSubTexture is a high-level texture defined as
a sub-region of some other parent texture. CoglSubTextures are high
level textures that implement the CoglMetaTexture interface which can
be used to manually handle texture repeating.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
This exposes CoglTextureRectangle in the experimental cogl 2.0 api. For
now we just expose a single constructor;
cogl_texture_rectangle_new_with_size() but we can add more later.
This is part of going work to improve our texture apis with more
emphasis on providing low-level access to the varying semantics of
different texture types understood by the gpu instead of only trying to
present a lowest common denominator api.
CoglTextureRectangle is notably useful for never being restricted to
power of two sizes and for being sampled with non-normalized texture
coordinates which can be convenient for use a lookup tables in glsl due
to not needing separate uniforms for mapping normalized coordinates to
texels. Unlike CoglTexture2D though rectangle textures can't have a
mipmap and they only support the _CLAMP_TO_EDGE wrap mode.
Applications wanting to use CoglTextureRectangle should first check
cogl_has_feature (COGL_FEATURE_ID_TEXTURE_RECTANGLE).
Reviewed-by: Neil Roberts <neil@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>
As part of the on going, incremental effort to purge the non type safe
CoglHandle type from the Cogl API this patch tackles most of the
CoglHandle uses relating to textures.
We'd postponed making this change for quite a while because we wanted to
have a clearer understanding of how we wanted to evolve the texture APIs
towards Cogl 2.0 before exposing type safety here which would be
difficult to change later since it would imply breaking APIs.
The basic idea that we are steering towards now is that CoglTexture
can be considered to be the most primitive interface we have for any
object representing a texture. The texture interface would provide
roughly these methods:
cogl_texture_get_width
cogl_texture_get_height
cogl_texture_can_repeat
cogl_texture_can_mipmap
cogl_texture_generate_mipmap;
cogl_texture_get_format
cogl_texture_set_region
cogl_texture_get_region
Besides the texture interface we will then start to expose types
corresponding to specific texture types: CoglTexture2D,
CoglTexture3D, CoglTexture2DSliced, CoglSubTexture, CoglAtlasTexture and
CoglTexturePixmapX11.
We will then also expose an interface for the high-level texture types
we have (such as CoglTexture2DSlice, CoglSubTexture and
CoglAtlasTexture) called CoglMetaTexture. CoglMetaTexture is an
additional interface that lets you iterate a virtual region of a meta
texture and get mappings of primitive textures to sub-regions of that
virtual region. Internally we already have this kind of abstraction for
dealing with sliced texture, sub-textures and atlas textures in a
consistent way, so this will just make that abstraction public. The aim
here is to clarify that there is a difference between primitive textures
(CoglTexture2D/3D) and some of the other high-level textures, and also
enable developers to implement primitives that can support meta textures
since they can only be used with the cogl_rectangle API currently.
The thing that's not so clean-cut with this are the texture constructors
we have currently; such as cogl_texture_new_from_file which no longer
make sense when CoglTexture is considered to be an interface. These
will basically just become convenient factory functions and it's just a
bit unusual that they are within the cogl_texture namespace. It's worth
noting here that all the texture type APIs will also have their own type
specific constructors so these functions will only be used for the
convenience of being able to create a texture without really wanting to
know the details of what type of texture you need. Longer term for 2.0
we may come up with replacement names for these factory functions or the
other thing we are considering is designing some asynchronous factory
functions instead since it's so often detrimental to application
performance to be blocked waiting for a texture to be uploaded to the
GPU.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
This exposes 2 experimental functions that make it possible to upload a
subregion of a texture from a CoglBuffer by first wrapping the buffer as
a CoglBitmap and then allowing uploading of a subregion from a
CoglBitmap. The new functions are:
cogl_bitmap_new_from_buffer() and
cogl_texture_set_region_from_bitmap()
Actually for now we are exporting this API for practical reasons since
we already had this API internally and it enables a specific feature
that was requested, but it is worth nothing that it's quite likely we
will replace these with functions that don't involve the CoglBitmap API
at some point.
For reference: The CoglBitmap API was actually removed from the 2.0
experimental API reference manual some time ago because the hope was
that we'd come up with a neater replacement. It doesn't seem entirely
clear what the scope of the CoglBitmap api is so it has became a bit of
a dumping ground. CoglBitmap is used for image loading, as a means to
represent the layout of image data and also internally deals with format
conversions.
Note: Because we are avoiding including CoglBitmap as part of the 2.0
API these functions aren't currently included in the 2.0 reference
manual.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
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.
* cogl_texture_get_data() is converted to use
_cogl_texture_foreach_sub_texture_in_region() to iterate
through the underlying textures.
* When we need to read only a portion of the underlying
texture, we set up a FBO and use _cogl_read_pixels()
to read the portion we need. This is enormously more
efficient for reading a small portion of a large atlas
texture.
* The CoglAtlasTexture, CoglSubTexture, and CoglTexture2dSliced
implementation of get_texture() are removed.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2414
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.
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 COGL_OBJECT_INTERNAL_DEFINE macro and friends that are the
same as COGL_OBJECT_DEFINE except that they prefix the cogl_is_*
function with an underscore so that it doesn't get exported in the
shared library.
There was a lot of common code that was copied to all of the backends
to convert the data to a suitable format and wrap it into a CoglBitmap
so that it can be passed to _cogl_texture_driver_upload_subregion_to_gl.
This patch moves the common code to cogl-texture.c so that the virtual
just takes a CoglBitmap that is already in the right format.
Previously cogl_texture_get_data would pretty much directly pass on to
the get_data texture virtual function. This ended up with a lot of
common code that was copied to all of the backends. For example, the
method is expected to return the required data size if the data
pointer is NULL and to calculate its own rowstride if the rowstride is
0. Also it needs to convert the downloaded data if GL can't support
that format directly.
This patch moves the common code to cogl-texture.c so the virtual is
always called with a format that can be downloaded directly by GL and
with a valid rowstride. If the download fails then the virtual can
return FALSE in which case cogl-texture will use the draw and read
fallback.
Instead of the ensure_mipmaps virtual that is only called whenever the
texture is about to be rendered with a min filter that needs the
mipmap, there is now a pre_paint virtual that is always called when
the texture is about to be painted in any way. It has a flags
parameter which is used to specify whether the mipmap will be needed.
This is useful for CoglTexturePixmapX11 because it needs to do stuff
before painting that is unrelated to mipmapping.
Instead of having a hardcoded series of if-statements in
cogl_is_texture to determine which types should appear as texture
subclasses, they are now stored in a GSList attached to the Cogl
context. The list is amended to using a new cogl_texture_register_type
function. There is a convenience macro called COGL_TEXTURE_DEFINE
which uses COGL_HANDLE_DEFINE_WITH_CODE to register the texture type
when the _get_type() function is first called.
This adds a _cogl_bind_gl_texture_transient function that should be used
instead of glBindTexture so we can have a consistent cache of the
textures bound to each texture unit so we can avoid some redundant
binding.
GL supports setting different wrap modes for the s, t and r
coordinates so we should design the backend interface to support that
also. The r coordinate is not currently used by any of the backends
but we might as well have it to make life easier if we ever add
support for 3D textures.
http://bugzilla.openedhand.com/show_bug.cgi?id=2063
Add a return result from CoglTexture.transform_quad_coords_to_gl(),
so that we can properly determine the nature of repeats in
the face of GL_TEXTURE_RECTANGLE_ARB, where the returned
coordinates are not normalized.
The comment "We also work out whether any of the texture
coordinates are outside the range [0.0,1.0]. We need to do
this after calling transform_coords_to_gl in case the texture
backend is munging the coordinates (such as in the sub texture
backend)." is disregarded and removed, since it's actually
the virtual coordinates that determine whether we repeat,
not the GL coordinates.
Warnings about disregarded layers are used in all cases where
applicable, including for subtextures.
http://bugzilla.openedhand.com/show_bug.cgi?id=2016
Signed-off-by: Neil Roberts <neil@linux.intel.com>
Since using addresses that might change is something that finally
the FSF acknowledge as a plausible scenario (after changing address
twice), the license blurb in the source files should use the URI
for getting the license in case the library did not come with it.
Not that URIs cannot possibly change, but at least it's easier to
set up a redirection at the same place.
As a side note: this commit closes the oldes bug in Clutter's bug
report tool.
http://bugzilla.openedhand.com/show_bug.cgi?id=521
When creating a Cogl sub-texture, if the full texture is also a sub
texture it will now just offset the x and y and reference the full
texture instead. This avoids one level of indirection when rendering
the texture which reduces the chances of getting rounding errors in
the calculations.
We've had complaints that our Cogl code/headers are a bit "special" so
this is a first pass at tidying things up by giving them some
consistency. These changes are all consistent with how new code in Cogl
is being written, but the style isn't consistently applied across all
code yet.
There are two parts to this patch; but since each one required a large
amount of effort to maintain tidy indenting it made sense to combine the
changes to reduce the time spent re indenting the same lines.
The first change is to use a consistent style for declaring function
prototypes in headers. Cogl headers now consistently use this style for
prototypes:
return_type
cogl_function_name (CoglType arg0,
CoglType arg1);
Not everyone likes this style, but it seems that most of the currently
active Cogl developers agree on it.
The second change is to constrain the use of redundant glib data types
in Cogl. Uses of gint, guint, gfloat, glong, gulong and gchar have all
been replaced with int, unsigned int, float, long, unsigned long and char
respectively. When talking about pixel data; use of guchar has been
replaced with guint8, otherwise unsigned char can be used.
The glib types that we continue to use for portability are gboolean,
gint{8,16,32,64}, guint{8,16,32,64} and gsize.
The general intention is that Cogl should look palatable to the widest
range of C programmers including those outside the Gnome community so
- especially for the public API - we want to minimize the number of
foreign looking typedefs.
The signbit macro is defined in C99 so it should be available but some
versions of GCC don't appear to define it by default. If it's not
available we can use a hack to test the bit directly.
There was a typo in getting the height of the full texture to check
whether the sub region fits so that it was using the width
instead. This was causing crashes when debugging is enabled for some
apps.
The sub texture backend doesn't work well as a completely general
texture backend because for example when rendering with cogl_polygon
it needs to be able to tranform arbitrary texture coordinates without
reference to the other coordintes. This can't be done when the texture
coordinates are a multiple of one because sometimes the coordinate
should represent the left or top edge and sometimes it should
represent the bottom or top edge. For example if the s coordinates are
0 and 1 then 1 represents the right edge but if they are 1 and 2 then
1 represents the left edge.
Instead the sub-textures are now documented not to support coordinates
outside the range [0,1]. The coordinates for the sub-region are now
represented as integers as this helps avoid rounding issues. The
region can no longer be a super-region of the texture as this
simplifies the code quite a lot.
There are two new texture virtual functions:
transform_quad_coords_to_gl - This transforms two pairs of coordinates
representing a quad. It will return FALSE if the coordinates can
not be transformed. The sub texture backend uses this to detect
coordinates that require repeating which causes cogl-primitives
to use manual repeating.
ensure_non_quad_rendering - This is used in cogl_polygon and
cogl_vertex_buffer to inform the texture backend that
transform_quad_to_gl is going to be used. The atlas backend
migrates the texture out of the atlas when it hits this.
This adds a new texture backend which represents a sub texture of a
larger texture. The texture is created with a reference to the full
texture and a set of coordinates describing the region. The backend
simply defers to the full texture for all operations and maps the
coordinates to the other range. You can also use coordinates outside
the range [0,1] to create a repeated version of the full texture.
A new public API function called cogl_texture_new_from_sub_texture is
available to create the sub texture.
