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Cogl 2.0 Reference Manual | ![]() |
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Top | Description |
CoglContext; CoglBool cogl_is_context (void *object
); CoglContext * cogl_context_new (CoglDisplay *display
,CoglError **error
); CoglDisplay * cogl_context_get_display (CoglContext *context
); enum CoglFeatureID; CoglBool cogl_has_feature (CoglContext *context
,CoglFeatureID feature
); CoglBool cogl_has_features (CoglContext *context
,...
); void (*CoglFeatureCallback) (CoglFeatureID feature
,void *user_data
); void cogl_foreach_feature (CoglContext *context
,CoglFeatureCallback callback
,void *user_data
); enum CoglReadPixelsFlags;
A CoglContext is the top most sandbox of Cogl state for an application or toolkit. Its main purpose is to act as a sandbox for the memory management of state objects. Normally an application will only create a single context since there is no way to share resources between contexts.
For those familiar with OpenGL or perhaps Cairo it should be understood that unlike these APIs a Cogl context isn't a rendering context as such. In other words Cogl doesn't aim to provide a state machine style model for configuring rendering parameters. Most rendering state in Cogl is directly associated with user managed objects called pipelines and geometry is drawn with a specific pipeline object to a framebuffer object and those 3 things fully define the state for drawing. This is an important part of Cogl's design since it helps you write orthogonal rendering components that can all access the same GPU without having to worry about what state other components have left you with.
Cogl does not maintain internal references to the context for resources that depend on the context so applications. This is to help applications control the lifetime a context without us needing to introduce special api to handle the breakup of internal circular references due to internal resources and caches associated with the context.
One a context has been destroyed then all directly or indirectly dependant resources will be in an inconsistent state and should not be manipulated or queried in any way.
For applications that rely on the operating system to clean up resources this policy shouldn't affect them, but for applications that need to carefully destroy and re-create Cogl contexts multiple times throughout their lifetime (such as Android applications) they should be careful to destroy all context dependant resources, such as framebuffers or textures etc before unrefing and destroying the context.
CoglBool cogl_is_context (void *object
);
Gets whether the given object references an existing context object.
|
An object or NULL
|
Returns : |
TRUE if the object references a CoglContext,
FALSE otherwise |
Since 1.10
Stability Level: Unstable
CoglContext * cogl_context_new (CoglDisplay *display
,CoglError **error
);
Creates a new CoglContext which acts as an application sandbox for any state objects that are allocated.
|
A CoglDisplay pointer |
|
A CoglError return location. |
Returns : |
A newly allocated CoglContext. [transfer full] |
Since 1.8
Stability Level: Unstable
CoglDisplay * cogl_context_get_display (CoglContext *context
);
Retrieves the CoglDisplay that is internally associated with the
given context
. This will return the same CoglDisplay that was
passed to cogl_context_new()
or if NULL
was passed to
cogl_context_new()
then this function returns a pointer to the
display that was automatically setup internally.
|
A CoglContext pointer |
Returns : |
The CoglDisplay associated with the
given context . [transfer none]
|
Since 1.8
Stability Level: Unstable
typedef enum { COGL_FEATURE_ID_TEXTURE_NPOT_BASIC = 1, COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP, COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT, COGL_FEATURE_ID_TEXTURE_NPOT, COGL_FEATURE_ID_TEXTURE_RECTANGLE, COGL_FEATURE_ID_TEXTURE_3D, COGL_FEATURE_ID_GLSL, COGL_FEATURE_ID_OFFSCREEN, COGL_FEATURE_ID_OFFSCREEN_MULTISAMPLE, COGL_FEATURE_ID_ONSCREEN_MULTIPLE, COGL_FEATURE_ID_UNSIGNED_INT_INDICES, COGL_FEATURE_ID_DEPTH_RANGE, COGL_FEATURE_ID_POINT_SPRITE, COGL_FEATURE_ID_MAP_BUFFER_FOR_READ, COGL_FEATURE_ID_MAP_BUFFER_FOR_WRITE, COGL_FEATURE_ID_MIRRORED_REPEAT, COGL_FEATURE_ID_GLES2_CONTEXT, COGL_FEATURE_ID_DEPTH_TEXTURE, COGL_FEATURE_ID_PRESENTATION_TIME, } CoglFeatureID;
All the capabilities that can vary between different GPUs supported
by Cogl. Applications that depend on any of these features should explicitly
check for them using cogl_has_feature()
or cogl_has_features()
.
The hardware supports non power
of two textures, but you also need to check the
COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP and COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT
features to know if the hardware supports npot texture mipmaps
or repeat modes other than
COGL_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE respectively.
|
|
Mipmapping is supported in conjuntion with non power of two textures. | |
Repeat modes other than
COGL_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE are supported by the
hardware.
|
|
Non power of two textures are supported
by the hardware. This is a equivalent to the
COGL_FEATURE_ID_TEXTURE_NPOT_BASIC , COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP
and COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT features combined.
|
|
Support for rectangular textures with non-normalized texture coordinates. | |
3D texture support | |
GLSL support | |
Offscreen rendering support | |
Multisample support for offscreen framebuffers | |
Multiple onscreen framebuffers supported. | |
Set if
COGL_INDICES_TYPE_UNSIGNED_INT is supported in
cogl_indices_new() .
|
|
cogl_pipeline_set_depth_range() support | |
Whether
cogl_pipeline_set_layer_point_sprite_coords_enabled() is supported.
|
|
Whether cogl_buffer_map() is
supported with CoglBufferAccess including read support.
|
|
Whether cogl_buffer_map() is
supported with CoglBufferAccess including write support.
|
|
Whether
COGL_PIPELINE_WRAP_MODE_MIRRORED_REPEAT is supported.
|
|
Whether creating new GLES2 contexts is suported. | |
Whether CoglFramebuffer support rendering the depth buffer to a texture. | |
Whether frame presentation time stamps will be recorded in CoglFrameInfo objects. |
Since 1.10
CoglBool cogl_has_feature (CoglContext *context
,CoglFeatureID feature
);
Checks if a given feature
is currently available
Cogl does not aim to be a lowest common denominator API, it aims to expose all the interesting features of GPUs to application which means applications have some responsibility to explicitly check that certain features are available before depending on them.
|
A CoglContext pointer |
|
A CoglFeatureID |
Returns : |
TRUE if the feature is currently supported or FALSE if
not. |
Since 1.10
Stability Level: Unstable
CoglBool cogl_has_features (CoglContext *context
,...
);
Checks if a list of features are all currently available.
This checks all of the listed features using cogl_has_feature()
and
returns TRUE
if all the features are available or FALSE
otherwise.
|
A CoglContext pointer |
|
A 0 terminated list of CoglFeatureIDs |
Returns : |
TRUE if all the features are available, FALSE
otherwise. |
Since 1.10
Stability Level: Unstable
void (*CoglFeatureCallback) (CoglFeatureID feature
,void *user_data
);
A callback used with cogl_foreach_feature()
for enumerating all
context level features supported by Cogl.
|
A single feature currently supported by Cogl |
|
A private pointer passed to cogl_foreach_feature() . |
Since 0.10
Stability Level: Unstable
void cogl_foreach_feature (CoglContext *context
,CoglFeatureCallback callback
,void *user_data
);
Iterates through all the context level features currently supported
for a given context
and for each feature callback
is called.
|
A CoglContext pointer |
|
A CoglFeatureCallback called for each supported feature |
|
Private data to pass to the callback |
Since 1.10
Stability Level: Unstable
typedef enum { /*< prefix=COGL_READ_PIXELS >*/ COGL_READ_PIXELS_COLOR_BUFFER = 1L << 0 } CoglReadPixelsFlags;
Flags for cogl_framebuffer_read_pixels_into_bitmap()
Since 1.0