Refresh viewport after updating RenderData width and height

shivamist

Hello,
I have a script that is used to update the resolution of the active document. Recently we implemented a way to get overscan size data (VFX work) and i'm having trouble with refreshing the viewport.
The issue resides in the fact that if you don't interact with the resolution slider or input something manually, the viewport show effectively the change with the Safe Frames but if there is an existing Background object/ Material with Frontal projection it will not update. Only an user interaction can help.

Here are some code snippets that i used to showcase the issue and what i tried in terms of flags/update/dirty states :

import c4d
import random

def main():
    doc = c4d.documents.GetActiveDocument()
    rd = doc.GetActiveRenderData()
    bd = doc.GetActiveBaseDraw()
    print(f"Render Data X_Res before : {rd[c4d.RDATA_XRES]}")
    print(f"Render Data Y_Res before : {rd[c4d.RDATA_YRES]}")
    print("-------------------------------------------------")
    xres = random.randint(0, 1920)
    yres = random.randint(0, 1080)
    rd[c4d.RDATA_XRES] = xres
    print(f"Render Data X_Res after : {rd[c4d.RDATA_XRES]}")
    rd[c4d.RDATA_YRES] = yres
    print(f"Render Data Y_Res after : {rd[c4d.RDATA_YRES]}")
    print("-------------------------------------------------")

    rd.Message(c4d.MSG_UPDATE)
    rd.SetDirty(c4d.DIRTYFLAGS_ALL)
    rd.SetDirty(c4d.DIRTYFLAGS_DATA)
    c4d.GeSyncMessage(c4d.EVMSG_UPDATEBASEDRAW)

    c4d.EventAdd()

if __name__=='__main__':
    main()

import c4d
import random

def main():
    doc = c4d.documents.GetActiveDocument()
    rd = doc.GetActiveRenderData()
    bd = doc.GetActiveBaseDraw()

    print(f"Render Data X_Res before: {rd[c4d.RDATA_XRES]}")
    print(f"Render Data Y_Res before: {rd[c4d.RDATA_YRES]}")
    print("-------------------------------------------------")

    xres = random.randint(1000, 1920)
    print(f"Random X_Res: {xres}")
    yres = random.randint(500, 1080)
    print(f"Random Y_Res: {yres}")

    # Set the new X and Y resolution using SetParameter
    rd.SetParameter(c4d.RDATA_XRES, xres, c4d.DESCFLAGS_SET_USERINTERACTION | c4d.DESCFLAGS_SET_FORCESET | c4d.DESCFLAGS_SET_INDRAG)
    rd.SetParameter(c4d.RDATA_YRES, yres, c4d.DESCFLAGS_SET_USERINTERACTION | c4d.DESCFLAGS_SET_FORCESET | c4d.DESCFLAGS_SET_INDRAG)

    print(f"Render Data X_Res after: {rd[c4d.RDATA_XRES]}")
    print(f"Render Data Y_Res after: {rd[c4d.RDATA_YRES]}")
    print("-------------------------------------------------")
    print("-------------------------------------------------")

    rd.Message(c4d.MSG_UPDATE)
    rd.SetDirty(c4d.DIRTYFLAGS_ALL)
    rd.SetDirty(c4d.DIRTYFLAGS_DATA)
    c4d.GeSyncMessage(c4d.EVMSG_UPDATEBASEDRAW)
    c4d.DrawViews(c4d.DRAWFLAGS_FORCEFULLREDRAW)
    c4d.EventAdd()

if __name__=='__main__':
    main()

Video showcasing the issue :

Thanks for your help in advance
C4D R2025.0.2

ferdinand

Hello @shivamist,

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

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About your First Question

You did a great job in your first posting with providing all the information we need. But I still struggle a bit with understanding your core issue. Your claim is "The issue resides in the fact that if you don't interact with the resolution slider or input something manually, the viewport [do not] show [...] the change with the Safe Frames [...] if there is an existing Background object/ Material with Frontal projection [...]".

I cannot reproduce this, nor does your video show that IMHO. Could you please elaborate and/or give us a scene file?

Cheers,
Ferdinand

This is what I did:

shivamist

@ferdinand
Here is the User action that fixes the viewport aspect ratio :

The process is :

Launch script
Open "Render Settings" windows
Either click or drag the width/height box in the Output videopost

Let me know if it's still unclear!

ferdinand

What I more meant was: What would you consider incorrect in my video/when running your script? And while I write this I sort of have an epiphany So, you mean your script fails when you have a BG object and the user manually interacts with the Render settings to change a value and you then run your script?

Because in my video and also yours, things are updating just fine I would say?

shivamist

@ferdinand
What's incorrect is the aspect ratio of the Background object or anything material that is in a Frontal projection

In the following screenshot you can see that on the border of the Safe Frames (turned them red for easier readability), the Background object stops at the border of the image

Here is the result after using the script with SetParameter() :

I hope the issue is clear now, the expected behavior would be that if the resolution changes, the background object should follow

ferdinand

Yes, this clarifies things, thanks a lot. I will have a look (but only tomorrow since I am now already on my Linux machine).

Cheers,
Ferdinand

ferdinand

Hey @shivamist,

After some poking in the code, I found out you were effectively writing to the wrong parameter, you should write to the virtual resolutions in this case, and also learnt something myself. Find my answer in detail below.

Cheers,
Ferdinand

Result

Code

"""Changes the resolution of the active RenderData in the active Cinema 4D document so that 
resolution dependent scene elements such as a Background object are updated accordingly.
"""

import c4d
from random import randint

# The active Cinema 4D document, you do not have to get that manually, it is automatically injected
# into most script modules by the Cinema 4D Python environment.
doc: c4d.documents.BaseDocument

def main() -> None:
    """Main logic of the script.
    """
    # Get the active render settings for the active document.
    rData: c4d.documents.RenderData = doc.GetActiveRenderData()

    # I quite frankly myself never did really understood the difference between the XRES and
    # XRES_VIRTUAL and YRES and YRES_VIRTUAL values until now. Just not to long ago I was joking
    # that VIRTUAL values are for when you only hypothetically want to change the resolution ;) But
    # after looking at some render data implementation code I now understand that you generally want
    # to write virtual values. One can think of XRES and YRES as hard set values where Cinema 4D will
    # not run extra logic to make sure that these values harmonize with the scene. XRES_VIRTUAL
    # and YRES_VIRTUAL on the other hand are soft set values which come with such checks. So, unless 
    # one wants to specifically bypass these checks, one should always write to the _VIRTUAL values.

    # One also does need indeed to set the DESCFLAGS_SET_USERINTERACTION flag here as 
    # RenderData.SetParameter does check for this. This also means that one should not use 
    # GeListNode.__setitem__ (the bracket operator) to set parameters on render data when one
    # requires correct GUI updates (for pure rendering it does not matter as far as I can tell).
    rData.SetParameter(c4d.RDATA_YRES_VIRTUAL, randint(1000, 1920), c4d.DESCFLAGS_SET_USERINTERACTION)
    rData.SetParameter(c4d.RDATA_XRES_VIRTUAL, randint(500, 1080), c4d.DESCFLAGS_SET_USERINTERACTION)

    c4d.EventAdd()


if __name__=='__main__':
    main()

shivamist

Hello @ferdinand ! Thanks for answer it is very clear, i will use virtual resolution from now on