svn merge ^/trunk/blender -r55372:55392

1 files changed, 23 insertions, 0 deletions

diff --git a/doc/python_api/examples/bpy.types.NodeTree.py b/doc/python_api/examples/bpy.types.NodeTree.py
new file mode 100644
index 00000000000..401b3a01ae0
--- /dev/null
+++ b/doc/python_api/examples/bpy.types.NodeTree.py
@@ -0,0 +1,23 @@
+"""
+Poll Function
++++++++++++++++
+The :class:`NodeTree.poll` function determines if a node tree is visible
+in the given context (similar to how :class:`Panel.poll`
+and :class:`Menu.poll` define visibility). If it returns False,
+the node tree type will not be selectable in the node editor.
+
+A typical condition for shader nodes would be to check the active render engine
+of the scene and only show nodes of the renderer they are designed for.
+"""
+import bpy
+
+
+class CyclesNodeTree(bpy.types.NodeTree):
+    """ This operator is only visible when Cycles is the selected render engine"""
+    bl_label = "Cycles Node Tree"
+
+    @classmethod
+    def poll(cls, context):
+        return context.scene.render.engine == 'CYCLES'
+
+bpy.utils.register_class(CyclesNodeTree)