images for the material shaders not assigned to the specified shader

lednevandrey

Hello everyone.

I am new to C4D scripts.
I may have posted this message in the wrong section of this forum, please let me know if that happened.

I want to create a script to get a material with certain properties and assign it to an object selected in the scene.
For the Brightness and Displacement channels, images from the disk are added.

import c4d
from c4d import storage

def main():

    # doc = c4d.documents.BaseDocument

    # Step 1: Create a new material
    material = c4d.BaseMaterial(c4d.Mmaterial)  # Creating new material
    material.SetName("MyMat")  # Assigning a name to a material
    doc.InsertMaterial(material)  # type: ignore # Adding material to a document

    # Step 2: Disable the Color Channel
    material[c4d.MATERIAL_USE_COLOR] = False

    # Step 3: Disable the Reflectivity channel
    material[c4d.MATERIAL_USE_REFLECTION] = False

     #Step 4: Enable the Brightness channel
    material[c4d.MATERIAL_USE_LUMINANCE] = True
    
    # Step 5: Select a texture file for the Brightness channel
    luminance_texture_path = storage.LoadDialog(type=c4d.FILESELECTTYPE_IMAGES, title="Select a texture for the Brightness channel")
    if luminance_texture_path:  # Checking if the user has selected a file
        luminance_shader = c4d.BaseShader(c4d.Xbitmap)  # Create a shader for the image
        luminance_shader[c4d.BITMAPSHADER_FILENAME] = luminance_texture_path  # Assigning a path to a file
        material[c4d.MATERIAL_LUMINANCE_SHADER] = luminance_shader  # Assigning a shader to a material
        
    # Step 6: Enable the DISPLACEMENTt channel
    material[c4d.MATERIAL_USE_DISPLACEMENT] = True

    # Step 7: Select a texture file for the Displacement channel
    displacement_texture_path = storage.LoadDialog(type=c4d.FILESELECTTYPE_IMAGES, title="Select a texture for the Displacement channel")
    if displacement_texture_path:  # Checking if the user has selected a file
        displacement_shader = c4d.BaseShader(c4d.Xbitmap)  # Create a shader for the image
        displacement_shader[c4d.BITMAPSHADER_FILENAME] = displacement_texture_path  # Assigning a path to a file
        material[c4d.MATERIAL_DISPLACEMENT_SHADER] = displacement_shader # Assigning a path to a file

    # Updating the material to apply the changes
    material.Update(True, True)

    # Step 8: Assign material to selected objects
    selected_objects = doc.GetActiveObjects(c4d.GETACTIVEOBJECTFLAGS_0)  # type: ignore # Get a list of selected objects
    if selected_objects:  # Checking if objects are selected
        for obj in selected_objects:
            texture_tag = c4d.TextureTag()  # Create a new texture tag
            texture_tag.SetMaterial(material)  # Assigning the material to the tag
            obj.InsertTag(texture_tag)  # Add a tag to the object

    # Updating the scene
    c4d.EventAdd()

# Script running
if __name__ == '__main__':
    main()

Why are the selected images for the material shaders not assigned to the specified shader?

edit (@ferdinand):
@lednevandrey said:

Script for S4D 2023.2

ferdinand

Hello @lednevandrey,

Welcome to the Maxon developers forum and its community, it is great to have you with us!

Getting Started

Before creating your next postings, we would recommend making yourself accustomed with our forum and support procedures. You did not do anything wrong, we point all new users to these rules.

Forum Overview: Provides a broad overview of the fundamental structure and rules of this forum, such as the purpose of the different sub-forums or the fact that we will ban users who engage in hate speech or harassment.
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It is strongly recommended to read the first two topics carefully, especially the section Support Procedures: Asking Questions.

About your First Question

The issue with your script is that you never insert your bitmap shaders. A shader must be inserted into a scene graph just like any other node before it can be used. Referencing a shader in a shader parameter does not replace inserting a shader. While for shaders this might be a bit surprising for beginners, one can look at it from an generator object angle to gain clarity. You would not expect to be able to link a that cube object into the document first. From this angle it is a bit more obvious that shaders are not any different and must be inserted before being linked anywhere.

In most cases shaders are owned by the material which use them and inserted with c4d.BaseList2D.InsertShader(). But there is some complexity to how shaders are structured when shaders own shaders. See Base Shader Manual: Access and Structure (C++) for details. The manual is for C++ but also applies to Python.

So, for the displacement part it should be for example something like this.

import c4d
import mxutils

# ...
path: str = storage.LoadDialog(type=c4d.FILESELECTTYPE_IMAGES, title="Select a texture for the Displacement channel")
if path:
    # The mxutils.CheckType call is here so that we can be sure that allocation did not fail. Then
    # we insert the shader into the document by attaching it to the material which itself
    # is being inserted into the document.
    shader: c4d.BaseShader = mxutils.CheckType(c4d.BaseShader(c4d.Xbitmap)
    material.InsertShader(shader)
    
    # Now we can link the file in the shader, and shader in the material. A shader can only
    # be linked/used once by a material in the classic APU of Cinema 4D. So, if we wanted
    # to use #path twice, we would have insert a second shader for the second usage.
    shader[c4d.BITMAPSHADER_FILENAME] = path
    material[c4d.MATERIAL_DISPLACEMENT_SHADER] = shader

Cheers,
Ferdinand

lednevandrey

Hi Ferdinand!

Thank you for your attention to my problem.
I took into account your comments and reworked the script. But when I run it, the console shows an error:

ModuleNotFoundError:No module named 'mxutils'

How to install a module 'mxutils' in the C4D environment?

ferdinand

Hey @lednevandrey,

Oh, my bad, I did not see that you were using 2023. mxutils is a feature of Cinema 4D 2024 and onwards. You cannot install it on 2023. Just replace lines like:

shader: c4d.BaseShader = mxutils.CheckType(c4d.BaseShader(c4d.Xbitmap)
material.InsertShader(shader)

with

shader: c4d.BaseShader = c4d.BaseShader(c4d.Xbitmap)
if shader is None:
    raise MemoryError("Failed to allocate shader.")
material.InsertShader(shader)

you technically also can write just

shader: c4d.BaseShader = c4d.BaseShader(c4d.Xbitmap)
material.InsertShader(shader)

when you are fine with a bit cryptic error when shader allocation fails; BaseList2D.InsertShader will then complain that it cannot deal with being passed a NoneType for its shader argument. Type checking only exists in Python for code to fail more gracefully. mxutils.CheckType just makes this just a little bit less cumbersome to do.

Cheers,
Ferdinand

lednevandrey

Hi Ferdinand!
Thank you. It worked.

ferdinand

Great to hear that you found your solution! Do not hesitate to ask more questions when you run into problems while exploring our Python API. But just as a heads up, we prefer users opening new topics for new questions. For details see the Support Procedures linked above.

Cheers,
Ferdinand