diff options
-rw-r--r-- | doc/python_api/examples/bpy.app.handlers.2.py | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/doc/python_api/examples/bpy.app.handlers.2.py b/doc/python_api/examples/bpy.app.handlers.2.py new file mode 100644 index 00000000000..aaaedeabecb --- /dev/null +++ b/doc/python_api/examples/bpy.app.handlers.2.py @@ -0,0 +1,23 @@ +""" +Note on Altering Data ++++++++++++++++++++++ + +Altering data from handlers should be done carefully. While rendering the +``frame_change_pre`` and ``frame_change_post`` handlers are called from one +thread and the viewport updates from a different thread. If the handler changes +data that is accessed by the viewport, this can cause a crash of Blender. In +such cases, lock the interface (Render → Lock Interface or +:data:`bpy.types.RenderSettings.use_lock_interface`) before starting a render. + +Below is an example of a mesh that is altered from a handler: +""" + +def frame_change_pre(scene): + # A triangle that shifts in the z direction + zshift = scene.frame_current * 0.1 + vertices = [(-1, -1, zshift), (1, -1, zshift), (0, 1, zshift)] + triangles = [(0, 1, 2)] + + object = bpy.data.objects["The Object"] + object.data.clear_geometry() + object.data.from_pydata(vertices, [], triangles) |