Have one Bumpmap Overide another at parts?

As the Title mentions,is there anyway to have two bump maps with one that is covering the top of the other. In my specific example a I have a mask,the mask has a generated rough plastic texture but certain parts are meant to have paint over them,this paint is meant to be raised up and i have a image bump map for this. For the parts with the paint i don’t want the rough plastic bumpmap being visible.

Is there anyway to do this?

Image Of Mask,i don’t want the roughness on the Green


Node Set up (ignore the unconnected Nodes,its for a glossy effect that i have not got working nicely yet)


To cancel out the voronoi on the green, you can make a mask from this green and plug it to the fac of a Mix RGB between the voronoi and pure black (or grey)

Im still somewhat new to Node stuff,so im still trying to figure out the finer details.So ill admit you lost me in some parts :P. Firstly do i need to do anything specific to create a ‘mask’ for it, do i need to change the texture colour,or greyscale it like my bump map? Secondly where on the node set up their should i plug the mix RBG,before the Gamma,after it,ect?

As Reference Here is my Texture and Bump Map, my Bump Map as a transparent background,will that effect anything?


Transparency will act as black.

Try this setup :


Thank you for all your help, just one final question though,and this is minor at best. When i do that though it does everything i want,but the paint indents in while i want it be pushed out? I can use a invert node between the Gamma and Mix but that inverts the Voronoi aswell.


Try white instead of grey then

That just seems to remove the bump all together on those parts, it seems like white is flat, while black is pushed in. Not sure if that may have something to do with the bumpmap itself.

In bumpmaps 50% grey is flat, everything brighter is moving up, everything darker is moving down, if I remember correctly.

Alternatively you can try something like this (using the Mask as a mix factor for 2 shaders, one with bump, one without bump):



which will give you a result like this:

Im aware of what its meant to be, im just saying that for whatever reason on mine, the white is acting as the neutral instead of the grey (It may be because the entire texture is pushed up or something thanks to the gamma,im not sure).

Your way at least for me doesn’t seem to want to work.




My end game plan was to have the plastic having that rough bump texture to it, with a normal image texture for the paint details, ontop of then having another image texture as the displacement for the paint details (giving it a paint stroke look).

You have to put the output of the voronoi texture into the height input of the bump node, not the normal

Well im a genius :stuck_out_tongue:

Thanks for the help aswell, its not entirely getting the same effect as the Displacement version though, im not sure wether its the nature of the Bump node or something else. I fiddled around with strength and distance a bit but still could not get it to quite look like Chameleon Scales set up.


The displacement seems to have a degree of randomness,like its natural defects and roughness in the plastic, the bump version seems to not have the same depth, and doesn’t quite get that plastic look that I want. Im not sure what is causing that effect i like in the plastic though,since the Voronoi is the exact same, im thinking maybe the mix RGB or the gamma is giving letting it get that more random effect or something,but im not sure.

the displacement input does actually perform bump. The only reason you have different results is because you plugged your bump on only one diffuse shader while you have 2 of them mixed together.

But let’s actually go back to the basics. Your first problem is that your mask (painted area) has sharp edges and you don’t want that.

Bump is just one way to make normals but the end result is still a normal map. Each pixel of the texture gets its own normal from a comparison between its own greyscale value and the values of its surroundings. When this normal is deducted, the pixel reacts to light according to it.
If the bump map goes straight from black to white without any in-between value, only the edge pixels will have very thin vertical normals, so it will not really show the difference in height between black and white, whereas if the edges are a bit softer, the normals converter has more in-between values to work with. You can see the difference here :


Now. Mixing 2 diffuse shaders can be done but doesn’t make much sense.
When you mix shaders it’s usually for using different types (Diffuse + Glossy for example)

If you want your bump to add up on top of the voronoi while masking it, the best way is actually to use an add node (MixRGB) and use the paint mask for both the color and the fac :


The Color Ramp node is there to sharpen the edge of the green color, but the soft edges are kept for the bump.
I kept the same texture with the sharp circles and soft circles so you see the difference again.

By the way :

As this post just demonstrated, that’s not how it works. There’s no such thing as a “flat” value. Any value is flat if surrounded by the same value, and non flat if surrounded by different values.
I guess what you meant by “flat” is “with an offset of 0” but again there’s no such thing as an offset once the bump map is converted to normals. Normals carry no height information. And there’s no 50% value either, since there’s no limit.

Actually let me show this last fact (that bump values have no limits) so you don’t have doubts on that :
Here is a texture with values from 0 to 1 :


Here it is as a bump map but multiplied by 100 :


Here is the same but with Clamp enabled, which clamps the values to 1 :


Thank you for all your help,i figured out a method based on your above node set up (just swapping out some colour inputs for some of my image textures and slipping the gamma in the right place.), i’m not sure how elegant it is,but it seems to work, and it lets me change the paint texture out with a more ‘painted’ version when i get that done.



((Damm Terminator Artefacting :P))

For the terminator artifact you have to either subdivide or use Blender Internal.