Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] I need help! => Topic started by: wardy_mk on 2023-06-06, 10:09:32

Title: Rendering out an alpha channel to 'cut out' an object
Post by: wardy_mk on 2023-06-06, 10:09:32

Hello. Can someone please tell me what the procedure is for rendering out a channel to 'cut out' an item in my render scene please? Usually I use an object buffer in the render tag along with multi-pass but I don't seem to have the option in Corona.

Any help much appreciated!

Title: Re: Rendering out an alpha channel to 'cut out' an object
Post by: Beanzvision on 2023-06-06, 11:35:51

Hi there, can you please share some examples? This would be a huge help.

Title: Re: Rendering out an alpha channel to 'cut out' an object
Post by: wardy_mk on 2023-06-06, 12:09:35

Here you go, have a look at the attached. This shows the procedure (last to first) of obtaining a 'masking' channel for the item I want to isolate.

Create an object. Create a render tag and drop it onto the object. Apply the Object Buffer to it. Go to render settings and enable multi pass and object buffer. Render it out and now I have an alpha channel in my document which I can use to 'cut out' the object.

Hope that makes sense!
I can give you this simple c4d file if you like?

Title: Re: Rendering out an alpha channel to 'cut out' an object
Post by: Beanzvision on 2023-06-06, 12:28:48

I'm not seeing where Corona is involved here. Everything seems C4D related so far.

Title: Re: Rendering out an alpha channel to 'cut out' an object
Post by: Nejc Kilar on 2023-06-06, 12:58:53

Howdy! From my understanding you're trying to create masks for objects much like you can with C4D's standard renderers and the Object Buffer workflows?

If so in Corona it is potentially even easier.

Go under the Corona menu (top bar) and bring up the MultiPass manager. In there search for the "Mask" pass (its under the mask category). Into its selection field you can simply drag the object you'd like to have a mask of. Do also make sure you switch the "no manual selection" option to "include selection".

Alternatively you can also leverage the "Object buffer ID" for pretty much the same workflow you had as with the C4D's Object Buffer functionality. In that case you want to set the "Object buffer ID" to X and then place a "Corona compositing" tag onto the object you want to mask out. Inside the "Corona compositing" tag you'll see you can set up the object buffer IDs.

Hope that helps. If not, we'll just try again :)

Title: Re: Rendering out an alpha channel to 'cut out' an object
Post by: wardy_mk on 2023-06-06, 16:46:08

EXCELLENT! That's what I was looking for. I knew there'd be a Corona-based alternative. Thanks!