Python scripting in Blender: how can I save a sequence of rendered images?

Question

I'm very new to Python scripting, so I've been trying something simple -- an animation of a bunch of cubes doing a 3D random walk.

I've managed to get the program to render every frame of the process, but I have no idea how to save each frame. Can anyone help?

Here's the code. What I'm missing would come in the def render_and_save function.

Cheers!

import bpy
import random

number_of_cubes = 10
animation_length = 10

def create_cubes(number_to_make):
    i = 0
    while i < number_to_make:
        bpy.ops.mesh.primitive_cube_add(radius=1, view_align=False, enter_editmode=False, location=(0, 0, 0))
        i += 1

def move_cube():
    bpy.ops.transform.translate(value=(random.randint(-1,1), random.randint(-1,1), random.randint(-1,1)), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

def select_cube(cube_name):
    bpy.ops.object.select_all(action = "DESELECT")
    bpy.ops.object.select_pattern(pattern = cube_name)

def move_all():
    j = 0
    while j < number_of_cubes:
        if j == 0:
            name_of_cube = "Cube"
            print(name_of_cube)
        elif j < 10:
            name_of_cube = "Cube.00" + str(j)
            print(name_of_cube)
        elif j < 100:
            name_of_cube = "Cube.0" + str(j)
            print(name_of_cube)
        select_cube(name_of_cube)
        move_cube()
        j += 1

def render_and_save(moves):
    bpy.ops.render.render(use_viewport = True)
    filename = str(moves)+".png"
    #But what should go here to make it save each image?

create_cubes(number_of_cubes)

moves = 0
while moves < animation_length:
    move_all()
    render_and_save(moves)
    moves += 1

Answer 1

By default bpy.ops.render.render() does not save single image renders. Simply set write_still=True to enable it.

def render_and_save(moves):
    bpy.context.scene.render.filepath = "//renders/"+str(moves)+".png"
    bpy.ops.render.render(use_viewport = True, write_still=True)

The filepath setting is the same value available in the output panel of the render settings. By putting "//render/" at the start of it will place the images in a folder called renders that is in the same folder as the blend file - the "//" is short for current blend file parent folder.