#!BPY
"""
Name: 'Material by Element'
Blender: 261
Group: 'Material'
Tooltip: 'Material by Element'
"""

import bpy
import random


print("MaterialByElement:")     #to test output...

scena = bpy.context.scene       #active scene
contesto = bpy.context          #context

N=10    #n. of material you want to be created
K=200   #KAOS - N*5 gives more contrast - N*10 is regular

#put here RGB values of main color:
r=0.4    #R
g=0.08   #G
b=0.04   #B

i = 0                           #reset counter

mats=bpy.data.materials

#unlink all materials and deletes them
for matter in mats:
    matter.user_clear()                 #unlink
    bpy.data.materials.remove(matter)   #remove "matter" from materials slot
    i+=1

i=0                             #reset counter

#creates new material set
for i in range(0,N):
    k=bpy.data.materials.new("MatByEl_"+str(i))
    #this is to have more difference between objects
    if i%2==0:
        k.diffuse_color=(r+(i/K), g+(i/K), b+(i/K))
    else:
        k.diffuse_color=(r-(i/K), g-(i/K), b-(i/K))

matter=bpy.data.materials

for obj in contesto.selected_objects:       #for every object in selection
    scena.objects.active = obj              #makes it active
    for mat in obj.material_slots:
        bpy.ops.object.material_slot_remove()   #remove all materials
    bpy.ops.object.material_slot_add()                  #add ONE material
    obj.data.materials[0]=matter[random.randrange(0,N-1)] #assign one of the N materials