Updating the texture image node using python

Question

Updating texture image node issue using python.

I have several different texture input files that I want to render out using the same node group setup and blender file.

Python doesn't seem to be updating the texture image node as expected

I'm using @Chris script located at https://blender.stackexchange.com/a/218744/86978

I've narrowed down the issue to the line bpy.data.images[fileName].filepath = eachFile # change this to you texture name

when it tries to execute this line it creates an error KeyError: 'bpy_prop_collection[key]: key "2plantpic_test.png" not found' or if I use the full path it gives this error KeyError: 'bpy_prop_collection[key]: key "/tmp/tex_tures/2plantpic_test.png" not found'

Things I've tried / checked:

1. The files are located in the directory /tmp/tex_tures/
2. If I rem out the line bpy.data.images[fileName].filepath = eachFile the files and directories get created but the different image texture files I want to be rendered out aren't rendered (since it doesn't change the texture image node).
3. Replaced the bpy.data.images line with eachFile = bpy.data.images.load(eachFile) but the image textures still aren't being updated to the new PNG images

How the script is suppose to work:

1. Loop through all PNG files in the /tmp/tex_tures
2. Replace the image texture file node with each PNG file found and render them out.
3. Place the render files into their own separate directory

The Script is below:

import bpy
import glob
import os


print ("Script start")

scn = bpy.context.scene

here = bpy.path.abspath('/tmp/tex_tures') #textures location

output_path = scn.render.filepath

for eachFile in glob.glob(os.path.join(here, '*.png')):
    print("-------------------")
    print("eachFile: ",eachFile)
    fileName = bpy.path.basename(eachFile)
    print("fileName: ",fileName)
    fileNameStart = os.path.splitext(fileName)[0]
    print("fileNameStart: ", fileNameStart)
    
    eachFile = bpy.data.images.load(eachFile)
    #bpy.data.images[fileName].filepath = eachFile # change this to you texture name
    #bpy.data.images[eachFile].filepath = eachFile # change this to you texture name
    #print("texture name used: ",bpy.data.images[fileName].name)
    #bpy.data.images['/tmp/tex_tures/2plantpic_test.png'].filepath = eachFile # change this to you texture name
    
    directory = os.path.join(here, fileNameStart)
    print("directory", directory)
    if not os.path.exists(directory):
        os.makedirs(directory)
    scn.render.filepath = os.path.join(directory,"")

    bpy.ops.render.render(animation=True)
    
bpy.context.area.ui_type = 'TEXT_EDITOR'

I'm using Ubuntu 20.04 Linux Blender 2.93.3 I've also attached the blender file and image of nodes

Thanks

Answer 1

You can use BlendDataImages.load() to load and assign the image to the texture node in one go as already explained in How to load an image from disc and assign it to a newly created image texture node?. How you can get a reference to any shader node is nicely explained in Control Cycles/Eevee material nodes and material properties using python?.

Demo on how to iterate through a list of images (by using the default hdris), assign each to the default cube, set the render path based on the originals and call the render operator:

import bpy
import os

C = bpy.context
scn = C.scene

# Get the images
folder = bpy.path.abspath("//images")
images = [os.path.join(folder, f) for f in os.listdir(folder) if f.endswith(".exr")] 

# Get the material
mat = C.object.active_material
nodes = mat.node_tree.nodes

# Get the node
img_node = nodes.get("__PLACEHOLDER__")
if img_node:
    # Iterate through all images, replace the image
    for img in images:
        img_node.image = bpy.data.images.load(img)
        # Set the output path and render (jpg is a placeholder)
        img_folder, img_file = os.path.split(img)
        img_name, img_ext = os.path.splitext(img_file)
        scn.render.filepath = bpy.path.abspath("//rndr_{}.jpg".format(img_name))

        bpy.ops.render.render(write_still=True)

As mentioned by @batFINGER in the comments, more god-like would be converting the list of images into a real sequence (img_000.exr, img_001.exr, img_002.exr etc.) and control the playback using the Offset property of the image node. Explanation: Is possible play video in reverse mode into Texture Image node?