Painting Vertex Colors does not update live in Cycles

There is a nice tutorial on painting with light from Max Hammond at Vimeo: https://vimeo.com/31659495

The problem I experience that Cycles does not catch the updates live. I am using the latest stable Blender 2.74 on Mac. When I paint vertex colors, the Cycles render viewport is not updated unless I exit vertex paint mode (pressing Tab) or perform a Shift-K fill. Regular brush painting does no trigger render restart. Any clues?

Thank you.

this is a code problem. It’s difficult to update cycles memory at any change, and it’s laborious to determine which change can or not update cycles memory, at a cost of usability… there may be a solution for vertexpaint calls, but it has not (yet) been writen. :frowning:

up to now, you’ll need to exit ‘renderedview’ and again enter, or to perform any action that triggers the update, just like the ones you described.

It may be related to why you can’t perform editmode operations when the rendered view is going, or why various editmode and objectmode graphics aren’t drawn ect…

I really wouldn’t call this a bug, as this would be a rather non-trivial thing to tackle (as in how you would handle updating the BVH tree and geometry data in real-time). I have not heard of any other app. that does this, if it was easy someone would’ve done it already.

Well, I wouldn’t be surprised if it didn’t work like that when testing it by myself.

The question raised when I saw it worked on a 3 years old video https://vimeo.com/31659495 (see at 13:47 Max paints vertices and the render view is updated live).

It works the same as in that tutorial in 2.74.

To update in real time the duplicate object that you are painting on has to have a subdivision surface modifier.

If you dont want to add a subsurf but still want the interactiveness, add a edge split modifier with sharp edges enabled (and edge angle disabled)

Great, thanks a lot! It works!!!