In general cogl-material.c has become far to large to manage in one
source file. As one of the ways to try and break it down this patch
starts to move some of lower level texture unit state management out
into cogl-material-opengl.c. The naming is such because the plan is to
follow up and migrate the very GL specific state flushing code into the
same file.
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.
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.
A pedantic change to get_fbconfig_for_depth() so that we don't need to
make any assumptions about the GLXFBConfig typedef or what values
we can overload to indicate an invalid config.
get_fbconfig_for_depth() now simply returns FALSE if it fails to find a
config.
This is a publicly exposed texture backend to create a texture which
contains the contents of an X11 pixmap. The API is currently marked as
experimental.
The backend internally holds a handle to another texture. All of the
backend virtuals simply redirect to the internal texture.
The texture can optionally be automatically updated if the
automatic_updates parameter is TRUE. If set then Cogl will listen for
damage events on the pixmap and update the texture accordingly.
Alternatively a damage object can be created externally and passed
down to Cogl.
The updates can be performed with XGetImage, XShmGetImage or the
GLX_EXT_texture_pixmap extension. If the TFP extension is used it will
optionally try to create a rectangle texture if the driver does not
support NPOTs or it is forced through the
COGL_PIXMAP_TEXTURE_RECTANGLE or CLUTTER_PIXMAP_TEXTURE_RECTANGLE
environment variables.
If the GLXFBConfig does not support mipmapping then it will fallback
to using X{Shm,}GetImage. It keeps a separate texture around for this
so that it can later start using the TFP texture again if the texture
is later drawn with mipmaps disabled.
