write-new-node.md

Writing a new libnodegl node

The vast majority of the code is "node code", in files following the node_*.c pattern. Since nodes need to be able to introspect each others, all their respective "private" context are declared in a common (not publicly exposed) header internal.h. This header also contains the structures definitions and prototypes required to implement a new node.

In order to add a node, you need to:

• in nodegl.h.in: declare a new NGL_NODE_* with an arbitrary unique FourCC
• create a node_*.c file declaring a const struct node_class. Don't forget the Copyright header. See other node files, such as node_identity.c
• in nodes_register.h: register the new node
• reference the source file node in libnodegl/meson.build
• run make nodegl-updatespecs (from the top-level Makefile) to update nodes.specs every time you update the parameters of the node
• similarly, run make nodegl-updatedoc to update the reference documentation after every change to the parameters
• refer to internal.h for the available callbacks to implement in your class map