NAME
dynload_overview - Dynamic Loading of Extension Nodes When Coin tries
to get hold of a node type object (SoType) for a class based on the
name string of the node type, it will - if no such node type has been
initialized yet - scan the file system for a dynamically loadable
extension node with that given name. This can be completely disabled by
setting the environment variable COIN_NO_SOTYPE_DYNLOAD to a positive
integer value, new from Coin v2.5.0.
On UNIX, extensions nodes are regular .so files. On Win32, extension
nodes are built as DLLs. On Mac OS X systems, extension nodes are built
as .dylib files. (Note: The extension nodes have to be built using the
flag ’-dynamiclib’, not ’-bundle’.)
Whether the dynamically loadable objects should be named with or
without the ’lib’ prefix is optional. Both schemes will work.
People don’t usually program in a way so that they instantiate new
nodes through the node class’ SoType object, but that is the way nodes
are created when model files are loaded. This means that for all Coin
applications that load model files, the custom extension nodes will
automatically be supported for the model files without you having to
modify their source code and rebuild the applications.
See ftp://ftp.coin3d.org/pub/coin/src/dynloadsample.tar.gz for an
example using two dynamically loadable extension nodes. You only use an
examiner viewer to view the two extension nodes in action.
Only a limited set of C++ compilers are supported as of yet. This is
because, to initialize the extension node, it is necessary to know
something about how the C++ compiler mangles the initClass symbol. If
we don’t know that, there is no way to locate the initClass method in
the library, which means the extension node can not make itself known
to the type system.
If your C++ compiler is not supported, the source file to add support
for a new compiler in is src/misc/cppmangle.icc. It is fairly trivial
to add support for new compilers, but if you don’t understand how, just
ask us about it. Patches with support for new compilers are of course
very welcome.
See also:
SoType
Since:
Coin 2.0