In Evee, I can create a shader node setup with two shaders (grass & dirt) and with a transparent & black png map which then allows me to use texture painting (add / subtract or Mix (black/white) to paint a dirt road into the grass.
But when I switch to Cycles, the road disappears and no painting mode works (add/subtract…add alpha/erase alpha…mix black/white)
Is there an easy way to convert this system to Cycles so I can render in cycles what I painted in Evee?
Thanks for any clues.
Texture paint mode will use the “internal” unsvaved image. Cycles needs to reload this image to see changes. to reload go out and in to cycles again.
Be careful in Cycles it does still paint but you do not see the updates, to se the updates you need to reload cycles (go to Eevee and back to cycles).
Thanks for suggestion, but If I paint in Cycles, it does not show. If I switch to Evee it does show. But when I switch back to Cycles, it still does not show.
Did you set the material up, with the image plugged in? Cycles needs the material to be setup for it to show, texture paint will show the image even if you do not plug it into the shader.
This is cycles and I can see the image (and transparency). As I said it does not update in Cycles, I have to go to Eevee and back to cycles for it to update.
Thanks for the suggestions. I finally found the answer: I must paint in Evee and then save the map in order for it to show in cycles.
Saving also does it but for me (4.1 up), I do not need to save the image, I do have to go back and forth from Eevee to cycles to see the painting (that way cycles reloads the texture.)
I can also paint in Cycles but I do not see the result until I go back to Eevee and then load cycles again.
I am on Linux but that should not matter.
It is best to keep saving the image while painting anyway just in case 
