How to animate vertex color of an object?

Question

Is it possible to animate the vertex color of an object?

Answer 1

Cycles

In Cycles Render, it's rather easy. Create your two Color Layers and animate the MixRGB's Fac: value.

I'm not familiar enough with Blender Internal to find a suitable answer for that engine. Luckily, brecht provided an answer

Blender Internal

Answer 2

manipulating Color Layer directly with Python as a function of frame number

We can animate a color_layer vertex by vertex procedurally with frame_change_pre handler, docs for which are here. This assumes that there is a vertex color map called 'Col', and that you know how to render Vertex Colors

import bpy
import random

obj = bpy.data.objects["Cube"]
mesh = obj.data

color_layer = mesh.vertex_colors["Col"]

def set_vcols(frame):
    i = 0
    for poly in mesh.polygons:
        for idx in poly.loop_indices:
            r = 0.5
            g = 255 / (frame % 255)
            b = random.random()
            color_layer.data[i].color = r,g,b
            i += 1

def my_handler(scene):
    frame = scene.frame_current
    set_vcols(frame)

bpy.app.handlers.frame_change_pre.append(my_handler)

If you go this route, while developing it might seem that your code is not being executed as you hoped, run the below code from console, then rerun your script:

purge the event list:

f_change = bpy.app.handlers.frame_change_pre
del f_change[0:len(f_change)]