OpenGL.contextdata

Storage of per-context values of various types

Because OpenGL needs persistent references to the objects we're constructing to shadow Python objects, we have to store references to the objects somewhere

For any given Python GUI library, we can use a weakref to the library's representation of the GL context to call the cleanup function. That means some per-GUI library code in OpenGL (or the library), but it gives us very natural operations within OpenGL.

Note: you can entirely disable use of this module by setting:

OpenGL.ERROR_ON_COPY = True OpenGL.STORE_POINTERS = False

before importing OpenGL functionality.

Functions

cleanupContext( context = None )

Cleanup all held pointer objects for the given context

Warning: this is dangerous, as if you call it before a context is destroyed you may release memory held by the context and cause a protection fault when the GL goes to render the scene!

Normally you will want to get the context ID explicitly and then register cleanupContext as a weakref callback to your GUI library Context object with the (now invalid) context ID as parameter.

delValue( constant , context = None )

Delete the specified value for the given context

constant: Normally a GL constant value, but can be any hashable value
context: the context identifier for which we're storing the value

getContext( context = None )

Get the context (if passed, just return)

context: the context ID, if None, the current context

getValue( constant , context = None )

Get a stored value for the given constant

constant: unique ID for the type of data being retrieved
context: the context ID, if None, the current context

setValue( constant , value , context = None , weak = False )

Set a stored value for the given context

constant: Normally a GL constant value, but can be any hashable value
value: the value to be stored. If weak is true must be weak-reference-able. If None, then the value will be deleted from the storage
context: the context identifier for which we're storing the value
weak: if true, value will be stored with a weakref Note: you should always pass the same value for "weak" for a given constant, otherwise you will create two storages for the constant.