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Request ; Random Per island Node

Posted: Mon Mar 16, 2020 1:57 pm
by Benny
Can this node be included with Luxcore in the near future :

- For making fast random colorvariation for Plants tree etc,.....
- For joined objects that need colervariation ,bump ,roughness etc...

Re: Request ; Random Per island Node

Posted: Mon Mar 16, 2020 2:09 pm
by Dade
Isn't already possible to achieve the same result using Object ID texture :?:

I remember some work has been done in BlendLuxCore about this topic.

Re: Request ; Random Per island Node

Posted: Mon Mar 16, 2020 2:55 pm
by Benny
No, can not be done with OBject id texture /color .

Only solution is to use random vertex color , but this verry slow to assign , compared to the new node with cycles Random Per island

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 8:55 am
by juangea
Dade, as Benny says it’s not possible right now.

Object ID gives random color per object, what that node does is to give random values per island, with this I mean that you can have 1 object with 10 leafs for example, and using that node inside the shader of that object will give you color variation in all the leafs, they are 1 object, not 10 objects, the object has 10 separated geometric parts,

Right now it’s impossible to generate random values for separated parts inside the same object, this was an option added to cycles recently, and it’s super important to give variation on floors, trees and plants, etc...

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 9:44 am
by Sharlybg
let me find a link it seem there is remap node for that purpose.

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 10:36 am
by Dade
juangea wrote: Tue Mar 17, 2020 8:55 am Object ID gives random color per object, what that node does is to give random values per island, with this I mean that you can have 1 object with 10 leafs for example, and using that node inside the shader of that object will give you color variation in all the leafs, they are 1 object, not 10 objects, the object has 10 separated geometric parts,

Right now it’s impossible to generate random values for separated parts inside the same object, this was an option added to cycles recently, and it’s super important to give variation on floors, trees and plants, etc...
I can write shape that can assign vertex colors based on this "island" concept. It is something to do as pre-processing because, indeed, I can not establish what is an "island" at run-time (during the rendering).

I could introduce this "island" concept in general: does Blender has this mesh information ? Can it be exported ?

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 11:07 am
by Sharlybg
IS that enough for your need ?
Random island.jpg

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 11:16 am
by juangea
All those boxes are joined in a single object?

If they are not, join them in a single mesh with a single material, and you will see no color variation, that's where the "random per island" comes into play.

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 11:28 am
by Benny
For more information you can take a look here :D ; Blender 2.82 & 2.83 etc... : https://developer.blender.org/rB1c2f7b022a

Re: Request ; Random Per island Node

Posted: Tue Mar 17, 2020 11:28 am
by Sharlybg
Aah now i understand your particular need. This is in Devs side :D