Struct
CoglMatrixEntry
Description [src]
struct CoglMatrixEntry {
/* No available fields */
}
Represents a single immutable transformation that was retrieved
from a CoglMatrixStack using cogl_matrix_stack_get_entry().
Internally a CoglMatrixEntry represents a single matrix
operation (such as “rotate”, “scale”, “translate”) which is applied
to the transform of a single parent entry.
Using the CoglMatrixStack api effectively builds up a graph of
these immutable CoglMatrixEntry structures whereby operations
that can be shared between multiple transformations will result
in shared CoglMatrixEntry nodes in the graph.
When a CoglMatrixStack is first created it references one
CoglMatrixEntry that represents a single “load identity”
operation. This serves as the root entry and all operations
that are then applied to the stack will extend the graph
starting from this root “load identity” entry.
Given the typical usage model for a CoglMatrixStack and the way
the entries are built up while traversing a scenegraph then in most
cases where an application is interested in comparing two
transformations for equality then it is enough to simply compare
two CoglMatrixEntry pointers directly. Technically this can lead
to false negatives that could be identified with a deeper
comparison but often these false negatives are unlikely and
don’t matter anyway so this enables extremely cheap comparisons.
CoglMatrixEntrys are reference counted using
cogl_matrix_entry_ref() and cogl_matrix_entry_unref() not with
g_object_ref() and g_object_unref().
Instance methods
cogl_matrix_entry_calculate_translation
Determines if the only difference between two transforms is a
translation and if so returns what the x, y, and z components of
the translation are.
cogl_matrix_entry_get
Resolves the current entry transform into a #graphene_matrix_t by
combining the sequence of operations that have been applied to
build up the current transform.
cogl_matrix_entry_ref
Takes a reference on the given entry to ensure the entry stays
alive and remains valid. When you are finished with the entry then
you should call cogl_matrix_entry_unref().
cogl_matrix_entry_unref
Releases a reference on entry either taken by calling
cogl_matrix_entry_unref() or to release the reference given when
calling cogl_matrix_stack_get_entry().