Script point light strength in cycles

You can do this by adding an event handler to the frame change event.

import bpy def my_handler(scene): fm = bpy.data.scenes['Scene'].frame_current if fm >= 1: lampStrength = 100 if fm >= 50: lampStrength = 200 if fm >= 100: lampStrength = 300 if fm >= 150: lampStrength = 400 scene.objects['Point'].data.node_tree.nodes['Emission'].inputs['Strength'].default_value=lampStrength print("lamp strength: " + str(lampStrength)) def register(): bpy.app.handlers.frame_change_post.append(my_handler) def unregister(): bpy.app.handlers.frame_change_post.remove(my_handler) if __name__ == "__main__": register() 

Credit for frame change portion of script here: Running a script for each frame

One alternative is to use a Driver: https://www.blender.org/manual/animation/drivers.html .

If you are using nodes for your lamp then you probably want to put the driver on your strength property.

When you configure a driver to use a script, you have to tell blender you trust the script. This usually means you have to save the file and reload it with driver scripts enabled (this often shows up as a button in the top bar when blender notices an untrusted script in a driver).

If the script is very deterministic, you might be able to replace it with keyframes. It is possible for a python script to compute keyframes.

Consider this excerpt from http://web.purplefrog.com/~thoth/blender/python-cookbook/animate-cycles-lamp-strength.html:

import bpy def mission1(obj): lamp = obj.data e_node = lamp.node_tree.nodes["Emission"] data_path = 'nodes["Emission"].inputs[1].default_value' for fr in [100, 130, 150, 200, 300]: fr2 = fr+10 e_node.inputs[1].default_value = 20 lamp.node_tree.keyframe_insert(data_path=data_path, frame=fr) e_node.inputs[1].default_value = 100 lamp.node_tree.keyframe_insert(data_path=data_path, frame=fr2) for fc in lamp.node_tree.animation_data.action.fcurves: for kp in fc.keyframe_points: kp.interpolation = 'CONSTANT' mission1(bpy.context.active_object) 

Blender 2.8

CYCLES render:

import bpy light = bpy.data.objects['Light'] light_strength = 1 light.data.use_nodes = True light.data.node_tree.nodes['Emission'].inputs['Strength'].default_value = light_strength 

EEVEE render:

import bpy light = bpy.data.objects['Light'] light_strength = 1000 light.data.energy = light_strength