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Functions
Description
Cogl provides portable access to the OpenGLES api through a single library that is able to smooth over inconsistencies between the different vendor drivers for OpenGLES in a single place.
The api is designed to allow Cogl to transparently implement the api on top of other drivers, such as OpenGL, D3D or on Cogl's own drawing api so even if your platform doesn't come with an OpenGLES 2.0 api Cogl may still be able to expose the api to your application.
Since Cogl is a library and not an api specification it is possible to add OpenGLES 2.0 api features to Cogl which can immidiately benefit developers regardless of what platform they are running on.
With this api it's possible to re-use existing OpenGLES 2.0 code within applications that are rendering with the Cogl API and also it's possible for applications that render using OpenGLES 2.0 to incorporate content rendered with Cogl.
Applications can check for OpenGLES 2.0 api support by checking for
COGL_FEATURE_ID_GLES2_CONTEXT
support with cogl_has_feature()
.
Functions
COGL_GLES2_CONTEXT_ERROR
#define COGL_GLES2_CONTEXT_ERROR (_cogl_gles2_context_error_quark ())
An error domain for runtime exceptions relating to the cogl_gles2_context api.
Since: 2.0
Stability Level: Unstable
cogl_gles2_context_new ()
CoglGLES2Context * cogl_gles2_context_new (CoglContext *ctx
,CoglError **error
);
Allocates a new OpenGLES 2.0 context that can be used to render to CoglOffscreen framebuffers (Rendering to CoglOnscreen framebuffers is not currently supported).
To actually access the OpenGLES 2.0 api itself you need to use
cogl_gles2_context_get_vtable()
. You should not try to directly link
to and use the symbols provided by the a system OpenGLES 2.0
driver.
Once you have allocated an OpenGLES 2.0 context you can make it
current using cogl_push_gles2_context()
. For those familiar with
using the EGL api, this serves a similar purpose to eglMakeCurrent.
COGL_FEATURE_ID_GLES2_CONTEXT
support
with cogl_has_feature()
. This function will return FALSE
and
return an COGL_GLES2_CONTEXT_ERROR_UNSUPPORTED
error if the
feature isn't available.Returns
A newly allocated CoglGLES2Context or NULL
if there
was an error and error
will be updated in that case.
Since: 2.0
Stability Level: Unstable
cogl_is_gles2_context ()
CoglBool
cogl_is_gles2_context (void *object
);
Gets whether the given object references a CoglGLES2Context.
Since: 2.0
Stability Level: Unstable
cogl_gles2_context_get_vtable ()
const CoglGLES2Vtable *
cogl_gles2_context_get_vtable (CoglGLES2Context *gles2_ctx
);
Queries the OpenGLES 2.0 api function pointers that should be
used for rendering with the given gles2_ctx
.
Returns
A pointer to a CoglGLES2Vtable providing pointers to functions for the full OpenGLES 2.0 api.
Since: 2.0
Stability Level: Unstable
cogl_push_gles2_context ()
CoglBool cogl_push_gles2_context (CoglContext *ctx
,CoglGLES2Context *gles2_ctx
,CoglFramebuffer *read_buffer
,CoglFramebuffer *write_buffer
,CoglError **error
);
Pushes the given gles2_ctx
onto a stack associated with ctx
so
that the OpenGLES 2.0 api can be used instead of the Cogl
rendering apis to read and write to the specified framebuffers.
Usage of the api available through a CoglGLES2Vtable is only
allowed between cogl_push_gles2_context()
and
cogl_pop_gles2_context()
calls.
If there is a runtime problem with switching over to the given
gles2_ctx
then this function will return FALSE
and return
an error through error
.
Parameters
ctx |
||
gles2_ctx |
A CoglGLES2Context allocated with
|
|
read_buffer |
A CoglFramebuffer to access to read operations such as glReadPixels. (must be a CoglOffscreen framebuffer currently) |
|
write_buffer |
A CoglFramebuffer to access for drawing operations such as glDrawArrays. (must be a CoglOffscreen framebuffer currently) |
|
error |
A pointer to a CoglError for returning exceptions |
Since: 2.0
Stability Level: Unstable
cogl_pop_gles2_context ()
void
cogl_pop_gles2_context (CoglContext *ctx
);
Restores the previously active CoglGLES2Context if there
were nested calls to cogl_push_gles2_context()
or otherwise
restores the ability to render with the Cogl api instead
of OpenGLES 2.0.
The behaviour is undefined if calls to cogl_pop_gles2_context()
are not balenced with the number of corresponding calls to
cogl_push_gles2_context()
.
Since: 2.0
Stability Level: Unstable
cogl_gles2_get_current_vtable ()
CoglGLES2Vtable *
cogl_gles2_get_current_vtable (void
);
Returns the OpenGL ES 2.0 api vtable for the currently pushed
CoglGLES2Context (last pushed with cogl_push_gles2_context()
) or
NULL
if no CoglGLES2Context has been pushed.
Returns
The CoglGLES2Vtable for the currently pushed
CoglGLES2Context or NULL
if none has been pushed.
Since: 2.0
Stability Level: Unstable
cogl_gles2_texture_2d_new_from_handle ()
CoglTexture2D * cogl_gles2_texture_2d_new_from_handle (CoglContext *ctx
,CoglGLES2Context *gles2_ctx
,unsigned int handle
,int width
,int height
,CoglPixelFormat format
);
Creates a CoglTexture2D from an OpenGL ES 2.0 texture handle that
was created within the given gles2_ctx
via glGenTextures()
. The
texture needs to have been associated with the GL_TEXTURE_2D target.
Parameters
ctx |
||
gles2_ctx |
A CoglGLES2Context allocated with
|
|
handle |
An OpenGL ES 2.0 texture handle created with
|
|
width |
Width of the texture to allocate |
|
height |
Height of the texture to allocate |
|
format |
The format of the texture |
Since: 2.0
Stability Level: Unstable
cogl_gles2_texture_get_handle ()
CoglBool cogl_gles2_texture_get_handle (CoglTexture *texture
,unsigned int *handle
,unsigned int *target
);
Gets an OpenGL ES 2.0 texture handle for a CoglTexture that can then be referenced by a CoglGLES2Context. As well as returning a texture handle the texture's target (such as GL_TEXTURE_2D) is also returned.
If the CoglTexture can not be shared with a CoglGLES2Context then
this function will return FALSE
.
This api does not affect the lifetime of the CoglTexture and you must take care not to reference the returned handle after the original texture has been freed.
TRUE
for low-level
CoglTextures such as CoglTexture2D or CoglTexture3D but
not for high level meta textures such as
CoglTexture2DSliced
Parameters
texture |
||
handle |
A return location for an OpenGL ES 2.0 texture handle |
|
target |
A return location for an OpenGL ES 2.0 texture target |
Since: 2.0
Stability Level: Unstable
Types and Values
CoglGLES2Context
typedef struct _CoglGLES2Context CoglGLES2Context;
Represents an OpenGLES 2.0 api context used as a sandbox for OpenGLES 2.0 state. This is comparable to an EGLContext for those who have used OpenGLES 2.0 with EGL before.
Since: 1.12
Stability Level: Unstable
struct CoglGLES2Vtable
struct CoglGLES2Vtable { };
Provides function pointers for the full OpenGLES 2.0 api. The api must be accessed this way and not by directly calling symbols of any system OpenGLES 2.0 api.
Since: 1.12
Stability Level: Unstable
enum CoglGLES2ContextError
Error codes that relate to the cogl_gles2_context api.
Members
Creating GLES2 contexts
isn't supported. Applications should use |
||
An underlying driver error occured. |