Automated Alpha Maps

[agitat3d]

Hi All,

I was wondering if it is possible to proceduraly create an alpha map that grows over time? Or maybe this definition is a little clearer; To have an area of transparency on an object grow over time

The Idea is that:

1. A point on a surface is defined

2. An area to be made transparent grows concentric to that point over time

3. I am very happy

Or

Maybe this area could be painted and then used as an alpha map?

Any suggestions?

Thanks muchly!

Edited April 13, 2008 by agitat3d

[zasid]

The Best bet would be to goto to your COP network

Do these steps

Goto the network view at the obj level set a COP2net node and go inside it .

put a Noise node

Uncheck per component option that will give u a black and white noise patterns which would act as ur procedural texture

Play around with the parameters and set the key frames where u like.

after the file node apply null node and name it something like Imageout.

now where ever you applying the texture in that field type the following.

op:obj/cop2net/imageout

This is will setup the procedural texture for you HTH !

[rdg]

you can also calculate the distance to the seed point (seed[xyz]):

like:

length(seedx -$TX, seedy - $TY, seed -$TZ) / multiplier

you can also use a chf("lookup", lenght()) lookup channel to controll the behaviour.

But this won't work for concave/convex object. so it might be better to do such calculations in UV space.

hm. The COP approach offers more control, probably.

[agitat3d]

Thank you. Thats certainly a good place to start

[agitat3d]

I was thinking of creating a rotoshape with its pivot == to the point on surface to start the concentric shape. Then I could scale the rotoshape from its pivot from a very small value getting larger over time. The rotoshape mask could then be applied to the alpha channel? Sounds like it could work?

[eetu]

Refinement for the copnet approach; make a rotoshape, drop a DilateErode COP after it and animate the size parameter.

You would need a clean uv-mapping though.

eetu.

[agitat3d]

Hi again,

I have assigned the image from cops to the map_base channel in shop. I have then assigned a meterial node to my object and pointed to the material node. My texture is not displaying. I am getting the error "Unable to access file ../../cop2net1/OUT_image"? Do I have to transfer the attributes or something like that?

[agitat3d]

Refinement for the copnet approach; make a rotoshape, drop a DilateErode COP after it and animate the size parameter.

You would need a clean uv-mapping though.

eetu.

Thank you. Helpful suggestion. That was my next task once have got the texture to assign to the object correctly.

[agitat3d]

The Best bet would be to goto to your COP network

Do these steps

Goto the network view at the obj level set a COP2net node and go inside it...

Here is my hip file if any one can tell me how to assign the procedural texture?

Kind thank yous

hip_and_geo.rar

[eetu]

Here's a quick fix.

You need to refer to it like "op:/obj/....../IMG_OUT" - you need the op: as it is expecting a filesystem path.

Also, I couldn't get it to be time-dependent with your shop network, so I just dropped a default material and it works

eetu.

decompose2.zip

[agitat3d]

Here's a quick fix.

You need to refer to it like "op:/obj/....../IMG_OUT" - you need the op: as it is expecting a filesystem path.

Also, I couldn't get it to be time-dependent with your shop network, so I just dropped a default material and it works

eetu.

Hi,

Thanks for sorting that for me it works a treat. Just a quick question. How does the geo know to assign that texture? Cant quite understand

Thanks again

[eetu]

Just a quick question. How does the geo know to assign that texture? Cant quite understand

Heh, check the "Material" tab on the object level geometry node.

Materials are the current sidefx-preferred method for applying shaders.

eetu.

[agitat3d]

Heh, check the "Material" tab on the object level geometry node.

Materials are the current sidefx-preferred method for applying shaders.

eetu.

Ah. Thanks for that one eetu. You've been most helpful.

[agitat3d]

Heh, check the "Material" tab on the object level geometry node.

Materials are the current sidefx-preferred method for applying shaders.

eetu.

Hey eetu,

I need to use the image generated in cops as an alpha but cant seem to get an alpa channel using your setup. Also the material seems to be repeating on every face? I dont quite understand why I cant just use a vex layered surface? urrrg

[eetu]

A Material is mostly just a container for the shader and e.g. a possible associated displacement shader.

Lay down a material node in a shop network, and inside that you can put your favourite shader. Remember to connect it to the material input.

It works with uv's just the same.

BTW, have you checked out the Material Palette? Or, gasp, the help file for materials?

eetu.

[agitat3d]

A Material is mostly just a container for the shader and e.g. a possible associated displacement shader.

Lay down a material node in a shop network, and inside that you can put your favourite shader. Remember to connect it to the material input.

It works with uv's just the same.

BTW, have you checked out the Material Palette? Or, gasp, the help file for materials?

eetu.

Hi ya,

Yeah I did try that and the diffuse works fine, however the alpha doesnt seem to have any effect. : (

for_eetu.rar

[eetu]

Your .tif texture didn't have anything in it's alpha.

Here the texture is loaded in the copnet, an alpha is keyed for it and then dilated.

The material gets the alpha'd image from the copnet using op:

Getting clearer?

eetu.

decompose_04.rar

[agitat3d]

Thank you for your time