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shaders and CopyOP


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Hello !

This is my first contribution! (and my first to a forum)

(I'm a french Houdini user (is there any others here? Houdini is very rare in France! what a pity )) :blink::ph34r:

Here is my problem:

i'd like to apply a vex shader whose input parameters vary on a per copy basis. (i'm interested in

re-creating the matrix effect where letters fall down, but the question is general).

Suppose :

I created a grid of spheres with

-a Sphere OP

-a Grid OP

-a Copy OP with source:Grid OP and template:SphereOP

i'd like then to apply the same shader to each copied sphere but i want a parameter of the shader

(saying the color, but it could be any parameter like the amount of noise...) to change with each sphere.

I can do some basic things like using a primitiveOP to set the color of each sphere ( with a param("something",0)

expression where "something" come from the copyOP).

I've got a result in interactive display and in OPenGl rendering.

But no result in mantra: all the spheres look the same.

thank you for your answers. :):)

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hello,

enfin un autre francais sur ce site!

but I am going to coninue in english just in case anyone wants to read this post...

actually, I am sorry I have no reply to your problem right now, but I am curious about it.

are you currently professionaly working with houdini? or is it a personnal stuff? I also know houdini is very rare in france, but I have heard that some are testing it. But I believe things are about to chage as houdini is getting quite known these days.

in my case I am currently trying to develop a project for tv, and I am testing which software are going to be used. And every day I am more convinced that I will use houdini. so, I will have to find houdini users! so I am glad to find at least one houdini user in france...

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http://b.fx.free.fr/ <--- also French

And yes, Houdini is quite rare... worldwide actually. Same goes for where I come from, the Netherlands.

But I don't really care though, wheter people want to use Houdini or not. I love to use it, that's all. And I think the (current) Houdini community is very nice :D

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Hi FrenchOP,

To do what you want, connect the Shader SOP to the geometry before the Copy SOP. Select the shader you want in the Shader SOP and the stamping parameters in the Copy SOP. Remember to turn on "Stamp Inputs" in the Copy SOP. Also note that "Use indirect references" in the Shader SOP must be toggled off.

Now, in the shader, you can add the param() function like you described and each copy should shade differently.

I hope the above helps!

Cheers!

steven

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