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I have a cube with a subdivision surface. I'm using the set position node, and a noise texture, to make the object bumpy. (See Photo) When I duplicate the object, I'd like the location of the noise to be randomly different on the other object. Is there a way to randomize the vector location of the noise texture per-object? Thanks!
This task seems quite simple at first glance, but on closer inspection it is quite tricky.
The problem here is that "random" is not really random in this case. From the outside it is, of course, but within a node tree it is not.
If you apply a node tree multiple times, the random value created in it will give the same result in all use cases, because the node Noise Texture generates the values based on the positions, which are always the same in all use cases.
Normally this is not relevant, because a random value is mostly related to the positions of the single vertices/edges/faces, but exactly this position should not be variable in your case.
If you use the position as a variable, you will get exactly the result you don't want: The random value changes when you move the object.
Therefore you have (at least) two possibilities to avoid the problem:
Control via Group Input
One possibility would be to "feed" an individual value from outside into the nodes, so that within the nodes a unique value can always be generated.
This could look like this:
Here I have created a Group Input of type Integer, where the vector for the node Noise Texture changes when it is modified.
This way, even when you move the object, the noise remains unchanged.
However, you have to set an individual "Seed" value for each object.
Control via Index
Another option would be to feed this variable value into a node tree from the outside, and create all objects in this one tree.
This could look like this:
Here I first create several Empties in a Collection. I use these as positions for the individual rocks.
Then I first use the node Collection Info in the node tree and instantiate several cubes at the positions of the Empties in it.
After that I capture the index and the position of the instances. The index is crucial here, because with this unique value per instance I can now control the displacement.
Unlike the previous variant, however, the position of the individual objects is always relative to the zero point of the object in which the nodes operate.
Therefore, I also capture the position of the instances to be able to compensate for this difference and achieve a displacement from the center of each individual object.
(Blender 3.2)
you can use this node setup:
result:
Note: but yes, if it would be the same location, it would be the same noise...
