Strange behaviour with Cycles nodes

hi all,

Yesterday, I had this idea of using the bump node and a cross product to have a new variation of the noise texture, and today while I was testing it, I found out that Cycles doesn’t use this result if I connect it to another bump node…
Here’s my setup:


As you can see, the emission is showing the correct values. But as soon as I connect this result to another bump node, Cycles don’t calculate this anymore!

Does anyone knows about this odd limitation?

Hmmmmmmmmmmmm

I was in doubt if Cycles couldn’t get the derivatives of nodes that already use derivatives… so I made a ‘small’ test, and I’ve manage to setup a workaround by creating an handmade ‘Bump node’… but still, this is not the best way to do it. :frowning: