I’m a bit stuck on texturing. I have a chimney with a texture, but I want it to be textured with soot. Now it looks like a new chimney, but I want it to look used. Can somebody help me with this?
Happy Blending!
You need to use a mask to mix the soot in. In your case I would probably paint the mask with texture paint. The mask should be a black and white image (black = 0 mix factor white = 1).
You can plug the mask image into the factor of a colour mix node to change the base colour (mixing the bricks colour with your soot colour).
You can also use the “mask” image to change the roughness etc.
Create a new image set up the colour mix nodes to mix the brick colour with a dirty soot colour, then go to texture paint and paint in the bits you want to be sooty.
I understand the theory, but I am still too inexperienced to put this into practice. Can you help me with the mask setting up the shading? Many thanks!
It depends how you want to mix the soot in.
If the top frame is the soot shader and the bottom one the bricks you can use a mask image plugged into the Mix shader node’s factor input.
An alternative would be use the mask to mix just the colour in just one principled BSDF like this:
Note that with this method the soot can share the normals of the bricks.
There are many ways you can use the mask as a factor to mix different things. For example you could add another colour mix node with 2 shades of grey to control the roughness input of the principled shader and plug the mask into the factor of that as well so the soot would have a different roughness value.
The rule of thumb is to use the mask as a factor to mix things.