(Bug): Issue with roto masking

[ApplicationCoding]

Make sure to follow our issue report guidelines

• [X] I'm using the latest version of Natron (not required but recommended)
• [X] I've restarted Natron and the issue persists
• [ ] I've run Natron via the command line and the issue persists
• [X] I've followed the contributing guidelines to the best of my understanding
• [X] My issue is not on the issue tracker or in a pull request already (go search for it and dig around a little bit!)
• [X] This bug is reproducible

Natron version

Natron 2.4.2

Operating system

Windows 10 21H2

System specs

RAM: 8GB CPU: Intel(R) Core(TM) i5-4460 CPU @3.20GHz GPU: Intel(R) HD Graphics 4600

Did you install Natron using the official installer?

• [X] Yes, I used the official installer
• [ ] No, I installed from a binary archive
• [ ] No, I compiled Natron from sources
• [ ] No, I installed Natron via another method

Custom installation path

No response

What were you trying to do?

On my animated short, I was trying to mask the smoke so that it looks behind the focal point. I used the roto and it did not work. So I used the Corner Pin node instead as an alternative to the roto node. Please refer to the image below to see if I have connected the nodes wrong or I have done a wrong step on rotoing.

What did you expect to happen? What happened instead?

It did not mask the clip. Project link: https://bit.ly/3sEclNL

Step-by-step reproduction instructions

1. Start Natron
2. Add a Read node
3. Add a Roto node
4. Add points

Additional details

No response

[Shrinks99]

This doesn't seem to be a bug, the roto node generates an alpha, you can then use a premult node to apply your alpha to the RGB channels. The cornerpin node is not an alternative to the roto node, it transforms images, but if it does what you want here that's great.

For more information on masking workflows in Natron, check out my forum post on the topic. Also if you have any other questions about how to use Natron the forum is a much better place to ask them!

[ApplicationCoding]

Oh okay. Thanks for the help @Shrinks99 🙂

[Shrinks99]

If your question has been answered you should close this issue :)

[ApplicationCoding]

The question has been answered. The forum issue did solve my problem. Thanks!