How to change the texture of an object after a few frames?

Question

So my question is that I want to change the texture of the object after a few frames. For example, after every 100 frames, the texture changes to the next texture. I have this little bit of code, so can you please.

import bpy
D = bpy.data
D.objects['Cube'].material_slots[0].material = D.materials['Material.001']

BTW, I am using blender 2.83.

Answer 1

for "changing materials" I might use a mix shader in a single material and key the Factor between 0 and 1, with animation. As you'll see in the screencap, the factor is in color showing that it was animated (by the following script)

It's important to notice that when you add Mix Shaders, they are not referenced by the (re)name you give them but appear to be "Mix Shader", "Mix Shader.001", "Mix Shader.002" and so on.

Per @MarkusvonBroady's comment below, you can also use Node Groups to mix "Material Outputs", to better organize what could become an unwieldly number of nodes in a single Material definition. Here is the file.

for node in bpy.data.materials["MyMatl with mixer"].node_tree.nodes:
    print(node)
bpy.data.materials["Material.003"].node_tree.nodes["Mix Shader.001"].inputs[0].default_value = 0
bpy.data.materials["Material.003"].node_tree.nodes["Mix Shader.001"].inputs[0].keyframe_insert('default_value', frame=1)
bpy.data.materials["Material.003"].node_tree.nodes["Mix Shader.001"].inputs[0].keyframe_insert('default_value', frame=49)
bpy.data.materials["Material.003"].node_tree.nodes["Mix Shader.001"].inputs[0].default_value = 1
bpy.data.materials["Material.003"].node_tree.nodes["Mix Shader.001"].inputs[0].keyframe_insert('default_value', frame=50)

Answer 2

I had time and interest to conjure up an example python script that may do what you're looking for: to reassign a material based on a frame change. It uses a call-back Handler that subscribes to frame changes and applies a different material when it detects a frame # boundary change. You'd want to enhance this perhaps with a list of frame changes and Material names in two lists, for multiple materials.

This assume objects['Cube'], and materials['Material.001'] and materials['Material.002']

The file contains the script and demo object and materials (plus an extra animated sphere). Note that I also incorporated @MarkusvonBroady's Group technique as an example applied to the Sphere object as Material.003.

import bpy
matlID=0
this handler will is set up to be called with the "handlers.frame_change_pre" callback for every frame change
def frame_change_handler( scene ):
    global matlID
    print( "frame=", bpy.context.scene.frame_current )
    currFrame = bpy.context.scene.frame_current
    print(matlID)
    if ( (currFrame >= 10) and (matlID!=2) ):
        print("change to Material.002")
        D.objects['Cube'].material_slots[0].material = bpy.data.materials['Material.002']
        matlID=2
    if ( (currFrame < 10) and (matlID!=1) ):
        print("change to Material.001")
        D.objects['Cube'].material_slots[0].material = bpy.data.materials['Material.001']
        matlID=1
D = bpy.data
initialize to first material
D.objects['Cube'].material_slots[0].material = D.materials['Material.001']
matlID=1
for m in D.materials:
    print(m)
bpy.app.handlers.frame_change_pre.clear()
bpy.app.handlers.frame_change_pre.append( frame_change_handler )
print( "frame_change being tracked" )
```