Glossy material over bump

Experimenting with cycles - it quickly became apparent that there is currently a limitation in the way bump maps are handled. They apply to the final material node only and therefore affect all shaders applied to the object. This means that you cannot for example have a bump on one shader - and apply a smooth glossy finish over the top. I think bump maps would be better moved to the shader node level (would give greater flexibility) - but for now, I did have a brainwave for a workaround. Basically I rendered the scene twice, once with the underlying bump material and once with the gloss overlay - I then composited them together.

It gives a great sense of depth to the material - almost as if the sphere is lacquered.


That’s a cool effect. I haven’t composited 2 scenes together. Is that a relatively straight forward node set up?

Yep - just render either the glossy or bump, save it. Then render the other. Go into the compositor node, add an image input node and load your saved image into it, then add a colour mix node (set to either mix, add or screen - depending on the effect you are after) and input both the image input node and the current render layer node in a ratio that best suits. 4 nodes in total.

I guess ideally you should render both images as separate layers (with the different materials in each layer) and composite them automatically (don’t know how to do that yet though - or even if it is possible).

Alternatively - is it possible for an object to hold two materials at once (and mix them)? You can certainly add two (or more) materials to a mesh - but there appears no way to mix them.

Can anyone give any pointers?


cool thank you! I’m not sure on your questions, maybe someone with the knowledge will show up :slight_smile:

Compositing is “the great big not-so secret.” Cycles is only one of several renderers that you can use at the same time. You don’t have to “get it all to come out perfectly in just one render,” and in fact it’s mostly a waste of time to try.