Hi
This is a cycles question.
Can someone please tell me in idiot terms how to paint in cycles?
I’ve managed to uv unrap and add a texture to an entire object, but that’s not what I always want. Im trying to paint some rust onto the corners of a cube for instance, this is where im going wrong some how.
In idiot steps can someone hold my hand please?
Cheers.
Here is how to paint on top of an image texture in cycles. This is not a great solution for rust, which should be done either with a procedural shader or with an image mask and an actual photo of rust. But if you want to paint on your cube…
Edit: after adding the image texture, change the coordinates to ‘UV’ from generated.
Hi, thanks for the reply.
When I get to step five, it covers the whole object in my rust texture 
Try the attached blend. The material looks complicated in the property tab, but if you look at it in the node editor it looks fine. Two textures, one splat map for the rust, the other is the actual rust.
rust-cube.blend (828 KB)
Hey thanks, that’s working, but I’m still confused lol. Going to study your node setup.
Thanks guys.
In essence you have a black and white image that controls how two shaders (with or without textures) are mixed together. For example, if you mix say, glass and diffuse together without changing any other parameters, you’ll get an object that looks like cloudy glass. In other words, it’s partly like a completely solid object, and partly like an object made entirely of glass. It’s half way between both. If you change the mix factor to say, 0.1, it’ll be 10% glass and 90% solid over the whole object. In other words it might start looking like fairly opaque plastic.
Now the cool part comes when you connect something to the factor so you get something other than a uniform mix between two shaders. Some examples of that something can be a noise texture, a calculated thing like fresnel or Z depth, or a UV mapped texture. In the attached example we use a black and white image to control the mix. So where the image is pure white it’ll be 100% ‘painted’ and where it’s pure black it’ll be 100% rusted. So using texture paint with a white brush, you can paint the sides of the cube to cover the rust with paint. Or, you could invert the image in the UV Image panel so it’s initially 100% no rust, and paint the edges with black in the 3D view to add rust where you want it. You can also paint with grey which will be a partial mix between paint and rust.
Hopefully that makes sense.
