Jump to: Board index » General » Fusion

How do you avoid negative RGBA values with matte control?

Learn about 3D compositing, animation, broadcast design and VFX workflows.
  • Author
  • Message
Offline

joemart

  • Posts: 81
  • Joined: Wed Apr 14, 2021 3:16 pm
  • Real Name: Joseph Martire

How do you avoid negative RGBA values with matte control?

PostTue Oct 04, 2022 4:09 pm

I'm substracting a polygon with another and the Alpha value seems to go below 0. How do I avoid this? Is there a way to default it to 0 if it goes below 0? How would I go about this?
Offline

Sander de Regt

  • Posts: 2782
  • Joined: Thu Nov 13, 2014 10:09 pm

Re: How do you avoid negative RGBA values with matte control

PostTue Oct 04, 2022 4:18 pm

How are you substracting them? What method are you using?
Sander de Regt

ShadowMaker SdR
The Netherlands
Offline
User avatar

Chad Capeland

  • Posts: 2887
  • Joined: Mon Nov 10, 2014 9:40 pm

Re: How do you avoid negative RGBA values with matte control

PostTue Oct 04, 2022 5:25 pm

You don't need MatteControl to subtract a mask. The masks themselves have a paint mode.
Chad Capeland
Indicated, LLC
www.floweffects.com
Offline

bentheanimator

  • Posts: 119
  • Joined: Mon May 13, 2019 10:38 pm
  • Real Name: Ben Hall

Re: How do you avoid negative RGBA values with matte control

PostTue Oct 04, 2022 7:13 pm

They're both right but if you need to floor a channel you can always add a Brightness and Contrast node. There's a check box for Clip Black and White. That will 0.0 black and stop White at 1.0.
Offline
User avatar

Bryan Ray

  • Posts: 2288
  • Joined: Mon Nov 28, 2016 5:32 am
  • Location: Los Angeles, CA, USA

Re: How do you avoid negative RGBA values with matte control

PostTue Oct 04, 2022 8:20 pm

Remember to tick the Alpha box if you need to clamp the alpha, though. BrightnessContrast has that unchecked by default.
Bryan Ray
http://www.bryanray.name
http://www.sidefx.com

Return to Fusion

Who is online

Users browsing this forum: No registered users and 13 guests