Although we wouldn't recommend developers try and interleve OpenGL drawing
with Cogl drawing - we would prefer patches that improve Cogl to avoid this
if possible - we are providing a simple mechanism that will at least give
developers a fighting chance if they find it necissary.
Note: we aren't helping developers change OpenGL state to modify the
behaviour of Cogl drawing functions - it's unlikley that can ever be
reliably supported - but if they are trying to do something like:
- setup some OpenGL state.
- draw using OpenGL (e.g. glDrawArrays() )
- reset modified OpenGL state.
- continue using Cogl to draw
They should surround their blocks of raw OpenGL with cogl_begin_gl() and
cogl_end_gl():
cogl_begin_gl ();
- setup some OpenGL state.
- draw using OpenGL (e.g. glDrawArrays() )
- reset modified OpenGL state.
cogl_end_gl ();
- continue using Cogl to draw
Again; we aren't supporting code like this:
- setup some OpenGL state.
- use Cogl to draw
- reset modified OpenGL state.
When the internals of Cogl evolves, this is very liable to break.
cogl_begin_gl() will flush all internally batched Cogl primitives, and emit
all internal Cogl state to OpenGL as if it were going to draw something
itself.
The result is that the OpenGL modelview matrix will be setup; the state
corresponding to the current source material will be setup and other world
state such as backface culling, depth and fogging enabledness will be also
be sent to OpenGL.
Note: no special material state is flushed, so if developers want Cogl to setup
a simplified material state it is the their responsibility to set a simple
source material before calling cogl_begin_gl. E.g. by calling
cogl_set_source_color4ub().
Note: It is the developers responsibility to restore any OpenGL state that they
modify to how it was after calling cogl_begin_gl() if they don't do this then
the result of further Cogl calls is undefined.
This function should only need to be called in exceptional circumstances
since Cogl can normally determine internally when a flush is necessary.
As an optimization Cogl drawing functions may batch up primitives
internally, so if you are trying to use raw GL outside of Cogl you stand a
better chance of being successful if you ask Cogl to flush any batched
geometry before making your state changes.
cogl_flush() ensures that the underlying driver is issued all the commands
necessary to draw the batched primitives. It provides no guarantees about
when the driver will complete the rendering.
This provides no guarantees about the GL state upon returning and to avoid
confusing Cogl you should aim to restore any changes you make before
resuming use of Cogl.
If you are making state changes with the intention of affecting Cogl drawing
primitives you are 100% on your own since you stand a good chance of
conflicting with Cogl internals. For example clutter-gst which currently
uses direct GL calls to bind ARBfp programs will very likely break when Cogl
starts to use ARBfb programs internally for the material API, but for now it
can use cogl_flush() to at least ensure that the ARBfp program isn't applied
to additional primitives.
This does not provide a robust generalized solution supporting safe use of
raw GL, its use is very much discouraged.
To allow for flushing of batched geometry within Cogl we can't support users
directly calling glReadPixels. glReadPixels is also awkward, not least
because it returns upside down image data.
All the unit tests have been swithed over and clutter_stage_read_pixels now
sits on top of this too.
The clutter_actor_pick() function just emits the ::pick signal
on the actor. Nobody should be using it, since the paint() method
is already context sensitive and will result in a ::pick emission
by itself. The clutter_actor_pick() is just confusing things.
The Clutter API reference should have a section on how to port
applications from older version of Clutter to the new API.
The first guide deals on how to port animations created with
ClutterEffect to clutter_actor_animate().
ActorBox should have methods for easily extracting the X and Y
coordinates of the origin, and the width and height separately.
These methods will make it easier for high-level language bindings
to manipulate ActorBox instances and avoid the Geometry type.
The Vertex and ActorBox boxed types are meant to be used across
the API, but are fairly difficult to bind. Their memory management
is also unclear, and has to go through the indirection of
g_boxed_copy() and g_boxed_free().
Merge branch 'master-clock-updates'
* master-clock-updates: (22 commits)
Change the paint forcing on the Text cache text
[timelines] Improve marker hit check and don't fudge the delta
Revert "[timeline] Don't clamp the elapsed time when a looping tl reaches the end"
[tests] Don't add a newline to the end of g_test_message calls
[test-timeline] Add a marker at the beginning of the timeline
[timeline] Don't clamp the elapsed time when a looping tl reaches the end
[master-clock] Throttle if no redraw was performed
[docs] Update Clutter's API reference
Force a paint instead of calling clutter_redraw()
Fix clutter_redraw() to match the redraw cycle
Run the repaint functions inside the redraw cycle
Remove useless manual timeline ticking
Move elapsed-time calculations into ClutterTimeline
Limit the frame rate when not syncing to VBLANK
Decrease the main-loop priority of the frame cycle
Avoid motion-compression in test-picking test
Compress events as part of the frame cycle
Remove stage update idle and do updates from the master clock
Call g_main_context_wakeup() when we start running timelines
Remove unused msecs_delta member
...
The clutter_redraw() function is used by embedding toolkits to
force a redraw on a stage. Since everything is performed by
toggling a flag inside the Stage itself and then letting the
master clock advance, we need a ClutterStage method to ensure
that we start the master clock and redraw.
The clutter_stage_fullscreen() and clutter_stage_unfullscreen() are
a GDK-ism. The underlying implementation is already using an accessor
with a boolean parameter.
This should take the amount of collisions between properties, methods
and signals to zero.
ClutterEvent is not really gobject-introspection friendly because
of the whole discriminated union thing. In particular, if you get
a ClutterEvent in a signal handler, you probably can't access the
event-type-specific fields, and you probably can't call methods
like clutter_key_event_symbol() either, because you can't cast the
ClutterEvent to a ClutterKeyEvent.
The cleanest solution is to turn every accessor into ClutterEvent
methods, accepting a ClutterEvent* and internally checking the event
type.
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1585
The texture filters are now a property of the material layer rather
than the texture object. Whenever a texture is painted with a material
it sets the filters on all of the GL textures in the Cogl texture. The
filter is cached so that it won't be changed unnecessarily.
The automatic mipmap generation has changed so that the mipmaps are
only generated when the texture is painted instead of every time the
data changes. Changing the texture sets a flag to mark that the
mipmaps are dirty. This works better if the FBO extension is available
because we can use glGenerateMipmap. If the extension is not available
it will temporarily enable automatic mipmap generation and reupload
the first pixel of each slice. This requires tracking the data for the
first pixel.
The COGL_TEXTURE_AUTO_MIPMAP flag has been replaced with
COGL_TEXTURE_NO_AUTO_MIPMAP so that it will default to
auto-mipmapping. The mipmap generation is now effectively free if you
are not using a mipmap filter mode so you would only want to disable
it if you had some special reason to generate your own mipmaps.
ClutterTexture no longer has to store its own copy of the filter
mode. Instead it stores it in the material and the property is
directly set and read from that. This fixes problems with the filters
getting out of sync when a cogl handle is set on the texture
directly. It also avoids the mess of having to rerealize the texture
if the filter quality changes to HIGH because Cogl will take of
generating the mipmaps if needed.
Units as they have been implemented since Clutter 0.4 have always been
misdefined as "logical distance unit", while they were just pixels with
fractionary bits.
Units should be reworked to be opaque structures to hold a value and
its unit type, that can be then converted into pixels when Clutter needs
to paint or compute size requisitions and perform allocations.
The previous API should be completely removed to avoid collisions, and
a new type:
ClutterUnits
should be added; the ability to install GObject properties using
ClutterUnits should be maintained.
Timelines no longer work in terms of a frame rate and a number of
frames but instead just have a duration in milliseconds. This better
matches the working of the master clock where if any timelines are
running it will redraw as fast as possible rather than limiting to the
lowest rated timeline.
Most applications will just create animations and expect them to
finish in a certain amount of time without caring about how many
frames are drawn. If a frame is going to be drawn it might as well
update all of the animations to some fraction of the total animation
rather than rounding to the nearest whole frame.
The 'frame_num' parameter of the new-frame signal is now 'msecs' which
is a number of milliseconds progressed along the
timeline. Applications should use clutter_timeline_get_progress
instead of the frame number.
Markers can now only be attached at a time value. The position is
stored in milliseconds rather than at a frame number.
test-timeline-smoothness and test-timeline-dup-frames have been
removed because they no longer make sense.
Clutter copies the gtk-doc from the usual gtk+ template, and
has a version.xml.in containing only:
@VERSION@
Without a newline at the end. Unfortunately, it appears that
autoconf has started adding a newline to the generated version.xml
which then is used as the payload for the "version" XML entity.
Instead of using a secondary file we can make configure generate
the whole clutter-docs.xml and cogl-docs.xml files from a template;
this way we also get the ability to substitute more autoconf variables
into the documentation -- if needs be.
This function can be used as an efficient way of drawing groups of
quads without using GL_QUADS. It generates a VBO containing the
indices needed to render using pairs of GL_TRIANGLES. The VBO is
globally cached so that it only needs to be uploaded whenever more
indices are requested than ever before.
The allocate_available_size() method is a convenience method in
the same spirit as allocate_preferred_size(). While the latter
will allocate the preferred size of an actor regardless of the
available size provided by the actor's parent -- and thus it's
suitable for simple fixed layout managers like ClutterGroup -- the
former will take into account the available size provided by the
parent and never allocate more than that; it is, thus, suitable
for simple fluid layout managers.
cogl_enable_depth_test and cogl_enable_backface_culling have been renamed
and now have corresponding getters, the new functions are:
cogl_set_depth_test_enabled
cogl_get_depth_test_enabled
cogl_set_backface_culling_enabled
cogl_get_backface_culling_enabled
This adds cogl_matrix api for multiplying matrices either by a perspective
or ortho projective transform. The internal matrix stack and current-matrix
APIs also have corresponding support added.
New public API:
cogl_matrix_perspective
cogl_matrix_ortho
cogl_ortho
cogl_set_modelview_matrix
cogl_set_projection_matrix
cogl_create_context is dealt with internally when _cogl_get_default context
is called, and cogl_destroy_context is currently never called.
It might be nicer later to get an object back when creating a context so
Cogl can support multiple contexts, so these functions are being removed
from the API until we get a chance to address context management properly.
For now cogl_destroy_context is still exported as _cogl_destroy_context so
Clutter could at least install a library deinit handler to call it.
Originally cogl_vertex_buffer_add_indices let the user pass in their own unique
ID for the indices; now the Id is generated internally and returned to the
caller.
It's now possible to add arrays of indices to a Cogl vertex buffer and
they will be put into an OpenGL vertex buffer object. Since it's quite
common for index arrays to be static it saves the OpenGL driver from
having to validate them repeatedly.
This changes the cogl_vertex_buffer_draw_elements API: It's no longer
possible to provide a pointer to an index array at draw time. So
cogl_vertex_buffer_draw_elements now takes an indices identifier that
should correspond to an idendifier returned when calling
cogl_vertex_buffer_add_indices ()
There were a number of functions intended to support creating of new
primitives using materials, but at this point they aren't used outside of
Cogl so until someone has a usecase and we can get feedback on this
API, it's being removed before we release Clutter 1.0.
This removes the following API:
cogl_material_set_blend_factors
cogl_material_set_layer_combine_function
cogl_material_set_layer_combine_arg_src
cogl_material_set_layer_combine_arg_op
These were rather awkward to use, so since it's expected very few people are
using them at this point and it should be straight forward to switch over
to blend strings, the API is being removed before we release Clutter 1.0.
Setting up layer combine functions and blend modes is very awkward to do
programatically. This adds a parser for string based descriptions which are
more consise and readable.
E.g. a material layer combine function could now be given as:
"RGBA = ADD (TEXTURE[A], PREVIOUS[RGB])"
or
"RGB = REPLACE (PREVIOUS)"
"A = MODULATE (PREVIOUS, TEXTURE)"
The simple syntax and grammar are only designed to expose standard fixed
function hardware, more advanced combining must be done with shaders.
This includes standalone documentation of blend strings covering the aspects
that are common to blending and texture combining, and adds documentation
with examples specific to the new cogl_material_set_blend() and
cogl_material_layer_set_combine() functions.
Note: The hope is to remove the now redundant bits of the material API
before 1.0
ClutterTexture has many properties that can only be accessed using
the GObject API. This is fairly inefficient and makes binding the
class overly complicated.
The Texture class should have accessor methods for all its properties,
properly documented.
Add a method for deleting the current selection inside a Text actor.
This is useful for subclasses.
See bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1521
Based on a patch by: Raymond Liu <raymond.liu@intel.com>
COGLenum, COGLint and COGLuint which were simply typedefs for GL{enum,int,uint}
have been removed from the API and replaced with specialised enum typedefs, int
and unsigned int. These were causing problems for generating bindings and also
considered poor style.
The cogl texture filter defines CGL_NEAREST and CGL_LINEAR etc are now replaced
by a namespaced typedef 'CoglTextureFilter' so they should be replaced with
COGL_TEXTURE_FILTER_NEAREST and COGL_TEXTURE_FILTER_LINEAR etc.
The shader type defines CGL_VERTEX_SHADER and CGL_FRAGMENT_SHADER are handled by
a CoglShaderType typedef and should be replaced with COGL_SHADER_TYPE_VERTEX and
COGL_SHADER_TYPE_FRAGMENT.
cogl_shader_get_parameteriv has been replaced by cogl_shader_get_type and
cogl_shader_is_compiled. More getters can be added later if desired.
Add a method for deleting the current selection inside a Text actor.
This is useful for subclasses.
See bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1521
Based on a patch by: Raymond Liu <raymond.liu@intel.com>
There were several functions I believe no one is currently using that were
only implemented in the GL backend (cogl_offscreen_blit_region and
cogl_offscreen_blit) that have simply been removed so we have a chance to
think about design later with a real use case.
There was one nonsense function (cogl_offscreen_new_multisample) that
sounded exciting but in all cases it just returned COGL_INVALID_HANDLE
(though at least for GL it checked for multisampling support first!?)
it has also been removed.
The MASK draw buffer type has been removed. If we want to expose color
masking later then I think it at least would be nicer to have the mask be a
property that can be set on any draw buffer.
The cogl_draw_buffer and cogl_{push,pop}_draw_buffer function prototypes
have been moved up into cogl.h since they are for managing global Cogl state
and not for modifying or creating the actual offscreen buffers.
This also documents the API so for example desiphering the semantics of
cogl_offscreen_new_to_texture() should be a bit easier now.
Bug 1513 - Allow passing in ClutterPickMode to
clutter_stage_get_actor_at_pos()
At the moment, clutter_stage_get_actor_at_pos() uses CLUTTER_PICK_ALL
internally to find an actor. It would be useful to allow passing in
ClutterPickMode to clutter_stage_get_actor_at_pos(), so that the caller
can specify CLUTTER_PICK_REACTIVE as a criteria.
Adds a new property so that the selection color can be different from
the cursor color. If no selection color is specified it will use the
cursor color as before. If no cursor color is specified either it will
use the text color.
ClutterGroup still ships with API deprecated since 0.4. We did
promise to keep it around for a minor release cycle -- not for 3.
Since we plan on shipping 1.0 without the extra baggage of the
deprecated entry points, here's the chance to remove the accumulated
cruft.
All the removed methods and signals have a ClutterContainer
counterpart.
Since we're planning to release 1.0 without any of the deprecated
API baggage, we can simply remove the set_uniform_1f() method from
ClutterShader public API and add it to the deprecated header.
This function was renamed a while ago in the .c file from
cogl_vertex_buffer_draw_range_elements but the corresponding .h and
doc/reference/cogl changes weren't made.
The Animation API should follow this pattern:
- functions with an Interval as part of the arguments should have
"interval" inside their name, e.g.:
clutter_animation_bind_interval
clutter_animation_update_interval
- functions dealing with property names should have "property"
inside their name, e.g.:
clutter_animation_has_property
clutter_animation_unbind_property
- unless -
- functions dealing with a property and its value should not
have any modifier, e.g.:
clutter_animation_bind
The change from update_property() to update_interval() frees up
clutter_animation_update(), to be added at a later date.
Bug 1438 - Implicit Animation API could use animatev variants
The clutter_actor_animate* family of functions use va_lists to
handle the property/value pairs for the final state of the
animation.
Language bindings have problems with variadic arguments functions,
and usually prefer vector-based API which allow a greater level
of control and conversion from native data types.
For each variadic arguments function in the clutter_actor_animate*
family there should be a vector-based version that takes:
- the number of property/value pairs
- a constant array of constant strings
- an array of GValues
Most of the internal implementation can be refactored from the
current one, thus both the var_args and the vector entry points
share a common implementation of the code; then, both versions
of the API are just loops over a list of arguments.
Based on a patch by: Robert Carr <carrr@rpi.edu>
The ClutterColor API has some inconsistencies:
- the string deserialization function does not match the rest of
the conversion function naming policy; the naming should be:
clutter_color_parse() -> clutter_color_from_string()
and the first parameter should be the ClutterColor that will
be set from the string, not the string itself (a GDK-ism).
- the fixed point API should not be exposed, especially in the
form of ClutterFixed values
- the non-fixed point HLS conversion functions do not make any
sense. The values returned should be:
hue := range [ 0, 360 ]
luminance := range [ 0, 1 ]
saturation := range [ 0, 1 ]
like the current fixed point API does. Returning a value in
the [ 0, 255 ] range is completely useless
- the clutter_color_equal() should be converted for its use inside
a GHashTable; a clutter_color_hash() should be added as well
- the second parameter of the clutter_color_shade() function should
be the shading factor, not the result (another GDK-ism). this way
the function call can be translated from this:
color.shade(out result, factor)
to the more natural:
color.shade(factor, out result)
This somewhat large commit fixes all these issues and updates the
internal users of the API.
In the future if we want to annotate matrices with internal flags, and add
caching of the inverse matrix then we need to ensure that all matrix
modifications are done by cogl_matrix API so we'd know when to dirty the
cache or update the flags.
This just adds documentation to that effect, and assuming the most likley
case where someone would try and directly write to matrix members would
probably be to load a constant matrix other than the identity matrix; I
renamed cogl_matrix_init_from_gl_matrix to cogl_matrix_init_from_array to
make it seem more general purpose.
Clutter uses checks on various environment variables and installs
various command line switches. The API reference should list them
and document them both.
The COGL_DEFINE_HANDLE macro generates a cogl_is_<type> function
as well, to check whether a CoglHandle opaque pointer is of type
<type>.
The handle for CoglMaterial does not export cogl_is_material() in
its installed header.
cogl_paint_init was a bit too miscellaneous; it mainly cleared the color, depth
and stencil buffers but arbitrarily it also disabled fogging and lighting.
It no longer disables lighting, since we know Cogl never enables lighting and
disabling of fog is now handled with a seperate function.
Since I noticed cogl_set_fog was taking a density argument documented as
"Ignored" I've also added a mode argument to cogl_set_fog which exposes the
exponential fog modes which can make use of the density.
This hides a number of internal structs and enums from the docs, and moves
some functions to more appropriate sections as well as misc description
updates (mostly for the vertex buffer api)
The :alignment property is prone to generate confusion: developers
will set it thinking that the contents of a ClutterText will
automagically align themselves.
Instead of using the generic term :alignment, and following the
GTK+ convention, we should use a more specific term, conveying the
actual effect of the property: alignment of the lines with respect
to each other, and not to the overall allocated area.
See bug 1428:
http://bugzilla.openedhand.com/show_bug.cgi?id=1428
Final bit of integration between ClutterActor and Pango: a simple
method for creating a PangoLayout, pre-filled with text and ready
to be rendered using cogl_pango_render_layout().
This should make writing new Actors rendering custom text in their
paint() implementation easy and reliable.
The Alpha API and usage has been changed by the recent overhaul
of the ClutterAlpha class; hence, we need to update the relative
documentation in the animation tutorial.
Bug 1349 - Using the anchor point to set the scale center is messy
The branch adds an extra center point for scaling which can be used
for example to set a scale about the center without affecting the
position of the actor.
The scale center can be specified as a unit offset from the origin or
as a gravity. If specified as a gravity it will be stored as a
fraction of the actor's size so that the position will track when the
actor changes size.
The anchor point and rotation centers have been modified so they can
be set with a gravity in the same way. However, only the Z rotation
exposes a property to set using a gravity because the other two
require a Z coordinate which doesn't make sense to interpret as a
fraction of the actor's width or height.
Conflicts:
clutter/clutter-actor.c
* generic-actor-clone:
Remove CloneTexture from the API
[tests] Clean up the Clone interactive test
Rename ActorClone to Clone/2
Rename ActorClone to Clone/1
Improves the unit test to verify more awkward scaling and some corresponding fixes
Implements a generic ClutterActorClone that doesn't need fbos.
Conflicts:
clutter/cogl/gl/cogl-texture.c
clutter/cogl/gles/cogl-primitives.c
* cogl-material:
clutter-{clone-,}texture weren't updating their material opacity.
Updates GLES1 support for CoglMaterial
Normalizes gl vs gles code in preperation for synching material changes
Removes cogl_blend_func and cogl_alpha_func
Fully integrates CoglMaterial throughout the rest of Cogl
[cogl-material] Restore the GL_TEXTURE_ENV_MODE after material_rectangle
[cogl-material] Make the user_tex_coords parameter of _rectangle const
[test-cogl-material] Remove return value from material_rectangle_paint
Add cogl-material.h and cogl-matrix.h to libclutterinclude_HEADERS
[cogl-material] improvements for cogl_material_rectangle
[cogl-material] Adds a cogl_material_set_color function
[cogl-material] Some improvements for how we sync CoglMaterial state with OpenGL
[cogl-material] Converts clutter-texture/clutter-clone-texture to the material API
[doc] Hooks up cogl-material reference documentation
Updates previous GLES multi-texturing code to use CoglMaterial
Adds a CoglMaterial abstraction, which includes support for multi-texturing
[doc] Hooks up cogl-matrix reference documentation
Adds CoglMatrix utility code
[tests] Adds an interactive unit test for multi-texturing
[multi-texturing] This adds a new cogl_multi_texture API for GL,GLES1 + GLES2
ClutterClone supercedes ClutterCloneTexture, since it can clone
every kind of actor -- including composite ones.
This is another "brain surgery with a shotgun" kind of commit: it
removes CloneTexture and updates every test case using CloneTexture
to ClutterClone. The API fallout is minimal, luckily for us.
The hope is that this function makes it easier to extend the font
settings with more flags without having to add a function for every
setting.
A new flag for enabling hinting has been added. If set, this changes
the font options on the global PangoContext and any newly created
PangoContexts. The options are only set if the flag is changed from
the default so it won't override any detailed setting chosen by the
backend.
The documentation has been updated to reflect the fact that the anchor
point will move when the actor changes size if it was specified using
a gravity value. The new functions for setting the scale center and z
rotation gravity are also documented.
The clutter_stage_get_resolution() and fixed-point API are just
shorthands for:
clutter_backend_get_resolution (default_backend);
And as such do not fit at all in the ClutterStage class. The only
reason for their existence was the ClutterUnit conversion macros,
which have now been fixed to use the default backend through a
function call instead.
Thus, we can safely remove the stage entry points.
* float-alpha-value:
[script] Parse easing modes by name
[docs] Update the easing modes documentation
[animation] Implement new easing functions
[animation] Move the alpha value to floating point
An em is a unit of measurement in typography, equal to the point
size of the current font.
It should be possible to convert a value expressed in em to
ClutterUnits by using the current font and the current DPI as
stored by the default backend.
The stage-with/height-percentage converters had been broken by
the multiple-stages support of Clutter 0.8. They are also made
useless by the fact that Units are now floating point values.
The millimeters and typographic points converters also depended
on the default stage, but they can be reworked to use the default
DPI coming from the default Backend instead.
This better reflects the fact that the api manages sets of vertex attributes,
and the attributes really have no implied form. It is only when you use the
attributes to draw that they become mesh like; when you specify how they should
be interpreted, e.g. as triangle lists or fans etc. This rename frees up the
term "mesh", which can later be applied to a concept slightly more fitting.
E.g. at some point it would be nice to have a higher level abstraction that
sits on top of cogl vertex buffers that adds the concept of faces. (Somthing
like Blender's mesh objects.) There have also been some discussions over
particle engines, and these can be defined in terms of emitter faces; so some
other kind of mesh abstraction might be usefull here.
Okey; to summarise the changes...
We have converted Clutter and Cogl over to using floating point internally
instead of 16.16 fixed, but we have maintained the cogl-fixed API as a
utility to applications in case they want to implement their own optimizations.
The Clutter API has not changed (though ClutterFixed and ClutterUnit are now
internally floats) but all Cogl entry points have been changed to accept floats
now instead of CoglFixed.
To summarise the rationale...
There have been a number of issues with using fixed point though out Clutter
and Cogl including: lack of precision, lack of range, excessive format
conversion (GPUs tend to work nativly with IEEE floats) and maintainability.
One of the main arguments for fixed point - performance - hasn't shown
itself to be serious in practice so far since we seem to be more limited
by GPU performance and making improvements regarding how we submit data to
OpenGL[ES]/the GPU has had a more significant impact.
Ref: The recent multiple rectangle queuing changes + the
cogl-texture-agressive-batching branch which show significant performance
gains, and that recent tests on the ipodtouch (ARM + MBX) also showed no
loss of performance running with floats.
So finally; please forgive the inevitable fallout, this is a far reaching
change. There are still a few known issues with the fixed to float
conversion but enough works for all our conformance tests to pass, and the
remaining issues hopefully wont be too tricky to solve. For reference two
tags will be available either side of this change: "cogl-fixed-end" and
"cogl-float-start"
The ClutterAlpha API reference page should also list the
easing modes Clutter provides by default, by showing the
curves used by each entry in the AnimationMode enumeration.
We can also remove the incomplete graph showing the old
alpha functions.
To deal with all the corner cases that couldn't be scripted a number of patches
were written for the remaining 10% of the effort.
Note: again no API changes were made in Clutter, only in Cogl.
In order to unify alpha functions and animation modes in ClutterAlpha
we should be able to register alpha functions and get a logical id
for them; the logical id will then be available to be used by
clutter_alpha_set_mode().
The registration requires API changes in ClutterAlpha constructors
and methods. It also provides the chance to shift ClutterAlpha
towards the use of animations modes only, and to alpha functions
as a convenience API for language bindings alone.
