BPY multi-rendering and file naming

Question

I am trying to create a script that would render my scene multiple times (let's say, a hundred times), with only some minor changes after each render. What I am trying to do is to render something, then make a change, and then render again, and repeat this process. Right now, I currently face two problems

How to ensure the rendering is first finished before any other changes are done? That means, render is commenced, finished, and then necessary changes are made to the scene? I already figured out that there exists a method in bpy.app.handlers (bpy.app.handlers.render_complete()) that triggers when rendering is done, but so far I did not figure out how to make it work. I am not even sure this is exactly the function I need and. Either way, I am not really sure about what argument is needed since documentation doesn't mention anything specifically.
How to set a name for a file that is being rendered? Right now I am using OS library to rename a file after it is rendered (since the file is labelled as "" defaultly), but this seems like an extremely unreliable way to do it (also, it raises some other problems that might pop up later.

I'm voting to close as a duplicate of: Is it possible to make a sequence of renders and give the user the option to cancel the process through the UI at any given time?, however, if you don't care about your script hanging, what you're trying to do is much simpler: using bpy.ops.render.render() will work, because it's synchronous - it hangs. The line below it will happen after the render finishes, so you can then safely edit the scene and render again. — Markus von Broady, Apr 21 '22 at 09:52

X Y · Answer 1 · 2022-04-21T11:24:48.323

Example to do something after render

# make sure your blend file is saved and in object mode
import bpy, bmesh
bpy.context.scene.render.image_settings.file_format = 'PNG'
bpy.context.scene.render.resolution_percentage = 10
def remove_first_vert(object_name):  # object type must: 'MESH'
    oj = bpy.data.objects[object_name]
    bpy.ops.object.mode_set(mode='EDIT')
    me = oj.data
    bm = bmesh.from_edit_mesh(me)
    bm.verts.ensure_lookup_table()
    bmesh.ops.delete(bm, geom=[bm.verts[0]], context='VERTS')
    bmesh.update_edit_mesh(me)
    bpy.ops.object.mode_set(mode='OBJECT')
for r in range(4):
    bpy.context.scene.render.filepath = f"//img_{r}.png"
    bpy.ops.render.render(write_still=True)
    #  Interface locked until render finish
remove_first_vert('Cube')

Print time when render done use bpy.app.handlers

# make sure your blend file is saved and in object mode
import bpy, bmesh
import time
from bpy.app.handlers import persistent
@persistent
def fn_print_time_when_render_done(dummy):
    print("----- the time is: ", time.time())
bpy.context.scene.render.image_settings.file_format = 'PNG'
bpy.context.scene.render.resolution_percentage = 10
def remove_first_vert(object_name):  # object type must: 'MESH'
    oj = bpy.data.objects[object_name]
    bpy.ops.object.mode_set(mode='EDIT')
    me = oj.data
    bm = bmesh.from_edit_mesh(me)
    bm.verts.ensure_lookup_table()
    bmesh.ops.delete(bm, geom=[bm.verts[0]], context='VERTS')
    bmesh.update_edit_mesh(me)
    bpy.ops.object.mode_set(mode='OBJECT')
bpy.app.handlers.render_complete.append(fn_print_time_when_render_done)
for r in range(4):
    bpy.context.scene.render.filepath = f"//img_{r}.png"
    bpy.ops.render.render(write_still=True)
    #  Interface locked until render finish
remove_first_vert('Cube')


bpy.app.handlers.render_complete.remove(fn_print_time_when_render_done)

BPY multi-rendering and file naming

1 Answers1

Example to do something after render

Print time when render done use bpy.app.handlers