Tthanks to @Calandro, I have discovered the dirty vertex paint mode!
This is a great start and I am now experimenting with how I can make the transition between the two materials more interesting.
Basically, I want to add some texture to the transition between the two material like on the screenshot below:
Can you show me the node setup you did use the magic texture? I can’t find it on the file you shared.
A word of advice for the future. Use “compress” when you save your files so they are not the huge files you share. I use only compressed Blend files in my work and never had a problem with them, so, compressing is a standard for me configured on the settings. That doesn’t affect files created before the change. Those files need to be “saved as” in order to select “compress” manually when saving them.
PS: I decided to investigate why your file was so huge and found out that you also packed an HDRI environment in the file. After unpacking it the file now has 178 KB instead of 70 MB. That’s a HUGE difference. Try using smaller HDRI images if you really need to pack them.
Oh, I see what the problem is. You are using a map range node to modulate the output of the attribute node, but you don’t know what values you have coming out from the vertex paint colors so you must rise a lot the maximum values and reduce a lot the minimum or you can do it as I did, and instead of using a map range node you use a ColorRamp node instead. It’s much easier to control visually.
I made a test here and found out that the minimum value you have in your vertex colors is 0.02 and the maximum is 0.914. You could try to work with that using the map range, but that would never give you the possibility to have as much control as you can have using a ColorRamp node. Including the use of many steps, if you desire. You could also use an RGB Curves node instead of the ColorRamp one, but that’s not as easy and intuitive as the ColorRamp.
