Is there a way I can randomize the sample seed?

Question

I want something so that when I hit Render, I get a certain noise pattern but then when I hit render a different time, without changing anything, I get a different one. Is there a time-based randomizer for the sample seed?

I'm using 2.8.

PS The clock button isn't useful for me because I want something where I can be on the same frame and get a different noise pattern

Answer 1

Let's put it into an add-on that one can install once and forget about it:

bl_info = {
    "name": "Random Render Seed",
    "author": "Martynas Ziemys",
    "version": (1, 0),
    "blender": (2, 80, 0),
    "location": "CyclesRenderSettings",
    "description": "Random Render seed EVERY TIME before rendering",
    "warning": " ",
    "wiki_url": " "
                "",
    "category": "Render",
}
import bpy, random
from bpy.app.handlers import persistent

@persistent
def RandomSeedHandler(scene):
    bpy.context.scene.cycles.seed = random.randint(10, 1000000000)

def register():
    bpy.app.handlers.render_pre.append(RandomSeedHandler)

def unregister():
    bpy.app.handlers.render_pre.remove(RandomSeedHandler)

if __name__ == "__main__":
    register()

If this is copied to a new text block and saved with .py extension it can be installed as an add-on.

Answer 2

Disclaimer: I can't code, but can copypaste snippets.

This script changes seed on every F12 render in 0-1000 range. Viewport update is laggy, so the number will change only on mouse hovering:

import bpy
from random import randint

def change_seed(scene):

    bpy.data.scenes["Scene"].cycles.seed = randint(0,1000)

bpy.app.handlers.render_pre.append(change_seed)