blender-impl-animation

Quick Reference

Critical Warnings

ALWAYS set the property value BEFORE calling keyframe_insert() — keyframes record the current value at call time.

ALWAYS call fcurve.update() after manually adding or modifying keyframe points via keyframe_points.add() or direct .co assignment.

ALWAYS create animation_data before accessing .action or .nla_tracks — call obj.animation_data_create() if obj.animation_data is None.

NEVER use bone.layers or pose.bone_groups in Blender 4.0+ — removed. Use BoneCollection API.

NEVER insert keyframes on objects not linked to any collection — they will exist in bpy.data but have no scene presence.

ALWAYS call scene.frame_set(frame) when you need depsgraph evaluation at that frame (e.g., for visibility keyframes, constraint evaluation). Direct scene.frame_current = frame does NOT trigger depsgraph update.

ALWAYS use bpy.data.objects.get("Name") with None-check instead of direct key access bpy.data.objects["Name"] — prevents KeyError crashes.