As part of an incremental process to have Cogl be a standalone project we
want to re-consider how we organise the Cogl source code.
Currently this is the structure I'm aiming for:
cogl/
cogl/
<put common source here>
winsys/
cogl-glx.c
cogl-wgl.c
driver/
gl/
gles/
os/ ?
utils/
cogl-fixed
cogl-matrix-stack?
cogl-journal?
cogl-primitives?
pango/
The new winsys component is a starting point for migrating window system
code (i.e. x11,glx,wgl,osx,egl etc) from Clutter to Cogl.
The utils/ and pango/ directories aren't added by this commit, but they are
noted because I plan to add them soon.
Overview of the planned structure:
* The winsys/ API is the API that binds OpenGL to a specific window system,
be that X11 or win32 etc. Example are glx, wgl and egl. Much of the logic
under clutter/{glx,osx,win32 etc} should migrate here.
* Note there is also the idea of a winsys-base that may represent a window
system for which there are multiple winsys APIs. An example of this is
x11, since glx and egl may both be used with x11. (currently only Clutter
has the idea of a winsys-base)
* The driver/ represents a specific varient of OpenGL. Currently we have "gl"
representing OpenGL 1.4-2.1 (mostly fixed function) and "gles" representing
GLES 1.1 (fixed funciton) and 2.0 (fully shader based)
* Everything under cogl/ should fundamentally be supporting access to the
GPU. Essentially Cogl's most basic requirement is to provide a nice GPU
Graphics API and drawing a line between this and the utility functionality
we add to support Clutter should help keep this lean and maintainable.
* Code under utils/ as suggested builds on cogl/ adding more convenient
APIs or mechanism to optimize special cases. Broadly speaking you can
compare cogl/ to OpenGL and utils/ to GLU.
* clutter/pango will be moved to clutter/cogl/pango
How some of the internal configure.ac/pkg-config terminology has changed:
backendextra -> CLUTTER_WINSYS_BASE # e.g. "x11"
backendextralib -> CLUTTER_WINSYS_BASE_LIB # e.g. "x11/libclutter-x11.la"
clutterbackend -> {CLUTTER,COGL}_WINSYS # e.g. "glx"
CLUTTER_FLAVOUR -> {CLUTTER,COGL}_WINSYS
clutterbackendlib -> CLUTTER_WINSYS_LIB
CLUTTER_COGL -> COGL_DRIVER # e.g. "gl"
Note: The CLUTTER_FLAVOUR and CLUTTER_COGL defines are kept for apps
As the first thing to take advantage of the new winsys component in Cogl;
cogl_get_proc_address() has been moved from cogl/{gl,gles}/cogl.c into
cogl/common/cogl.c and this common implementation first trys
_cogl_winsys_get_proc_address() but if that fails then it falls back to
gmodule.
Multitexturing allows blending multiple layers of texture data when texturing
some geometry. A common use is for pre-baked light maps which can give nice
lighting effects relativly cheaply. Another is for dot-3 bump mapping, and
another is applying alpha channel masks.
The dot-3 bump mapping would be really nice one day, but currently cogl doesn't
support lighting so that's not dealt with in this patch.
notable limitations:
- It can only texture rectangles a.t.m - and like cogl_texture_rectangle there
is no support for rotated texturing.
- Sliced textures are not supported. I think I've figured out how to handle
layers with different slice sizes at least for rectangular geometry, but I'm
not sure how complex it becomes once rotations are possible and texturing
arbitrary cogl_polygons.
- Except for this new API, cogl still doesn't know about more than one texture
unit, and so has no way of caching any enables related to other units. So that
things don't break it's currently necessary to disable anything to do with
additional units as soon as we are done with them which isn't ideal.
- No clutter API yet.
* clutter/cogl/gles/cogl-gles2-wrapper.c: All of the settings and
uniforms are now proxied into COGL variables instead of setting
the GL uniforms directly. Just before glDrawArrays is executed a
shader is generated using the given settings to avoid using 'if'
statements. The shaders are cached.
* clutter/cogl/gles/cogl-fixed-vertex-shader.glsl:
* clutter/cogl/gles/cogl-fixed-fragment-shader.glsl: The shaders
are now split into parts using comments instead of 'if' statements
so that the simplest shader can be generated on the fly.
* clutter/cogl/gles/stringify.sh: Now splits up the shader sources
into separate C strings where deliminated by special comments.
* clutter/cogl/gles/cogl-program.h:
* clutter/cogl/gles/cogl-program.c: A custom shader can no longer
be directly linked with the fixed-functionality replacement
because the replacement changes depending on the settings. Instead
the bound shader is linked with the appropriate replacement shader
just before glDrawArrays is executed. The custom uniform variables
must also be proxied through COGL variables because their location
can change when relinked.
(cogl_gles2_wrapper_init): Get uniforms for fog parameters and
initialise them.
(cogl_wrap_glDrawArrays): Store the modelview matrix in a uniform
as well so that it can be used for fogging calculations.
(cogl_wrap_glEnable, cogl_wrap_glDisable): Enable/disable fogging.
(cogl_wrap_glFogx, cogl_wrap_glFogxv): Fill in wrapper to set
fogging parameters.
* clutter/cogl/gles/cogl-fixed-vertex-shader.glsl: Calculate the
fog amount if fogging is enabled.
* clutter/cogl/gles/cogl-fixed-fragment-shader.glsl: Mix with fog
color.
* clutter/cogl/gles/cogl-gles2-wrapper.h (CoglGles2Wrapper): Add
uniforms for fogging.
* clutter/eglx/clutter-stage-egl.h:
* clutter/eglx/clutter-egl-headers.h:
* clutter/eglx/clutter-backend-egl.h:
* clutter/eglx/Makefile.am: Include the GLES and EGL headers via
clutter-egl-headers.h so that the right version can be used
depending on whether the GLES 2 wrapper is being used.
* configure.ac: Added an automake conditional for whether the GLES
2 wrapper should be used.
* clutter/eglx/clutter-stage-egl.c (clutter_stage_egl_realize):
Remove the call to glGetIntegerv to get the max texture size. It
was being called before the GL context was bound so it didn't work
anyway and it was causing trouble for the GLES 2 simulator.
* clutter/cogl/gles/stringify.sh: Shell script to convert the
shaders into a C string.
* clutter/cogl/gles/cogl-gles2-wrapper.h:
* clutter/cogl/gles/cogl-gles2-wrapper.c: Wrappers for most of the
missing GL functions in GLES 2.
* clutter/cogl/gles/cogl-fixed-fragment-shader.glsl:
* clutter/cogl/gles/cogl-fixed-vertex-shader.glsl: New shaders for
GLES 2
* clutter/cogl/gles/cogl-defines.h.in: Use the @CLUTTER_GL_HEADER@
macro instead of always using the GLES 1 header.
* clutter/cogl/gles/cogl-context.h (CoglContext): Include a field
for the state of the GLES 2 wrapper.
* clutter/cogl/gles/cogl-texture.c:
* clutter/cogl/gles/cogl-primitives.c:
* clutter/cogl/gles/cogl.c: Use wrapped versions of the GL
functions where neccessary.
* clutter/cogl/gles/Makefile.am: Add sources for the GLES 2
wrapper and an extra build step to put the GLSL files into a C
string whenever the files change.
