Collapsible nodes, savable as presets would work for me.
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On
> Behalf Of Andy Jones
> Sent: 22 May 2007 23:12
> To: XSI(at)Softimage.COM
> Subject: Re: dissolve texture with alpha mask
>
> I think what you're hitting on is the sort of "damned if you do, damned
> if you don't" of nodes. I don't know if you've ever used Fusion or
> Shake, but if you look at those two programs, it's a pretty good
> example
> of how node-based systems can try to either put everything you might
> want into each node, or keep everything broken out into simple
> components. Both systems can have big advantages. Ultimately, a
> Fusion
> comp will often have fewer nodes because more operations are provided
> in
> each node. But in a Shake comp, you'll always know exactly what each
> node does with little fussing about. Which is better? Ultimately,
> it's
> just a matter of opinion, and depends on the individual. Personally, I
> usually prefer working with nodes that are fairly simple. That way I
> know exactly what everything is doing and can understand what is and
> isn't optimized. But at the same time, I find my shader trees in XSI
> to
> be pretty enormous by the time I finish them. Which is why I end up
> writing custom shaders instead.
>
> Ultimately, I think the happy medium lies with the ability to create
> "macros" that are sets of nodes combined to do a particular task.
> XSI's
> ability to do this is pretty limited, as it requires knowledge of spdl
> syntax. But it is possible. And in fact, quite a few of the shaders
> in
> XSI are actually several shaders bundled together into one. But there
> is certainly a lot of room for improvement in terms of making it easier
> to these types of shaders by combining nodes. With such a system, you
> would create a shader tree that does exactly what you want, providing
> the ability to manipulate your alpha however you want, then you'd
> reference that shader tree into your materials as a single node. And
> you could update it later, non-destructively.
>
> - Andy
>
> Ponthieux, Joey wrote:
>
> > Brad, Andy,
> > I finally got this to work. Thanks! It would seem that what I
> > needed was the a mix2colors node and that helped tremendously. I
> > managed to separate the alpha and and run it through an intensity
> > node. It worked fine.
> >
> > Am I missing something or doesn't this seem like an awful lot of
> extra
> > work for something which I think should be real fundamental. It
> > strikes me that if I set up a file->image->sprite->material network,
> > this is a real simple structure which quickly and simply generates
> the
> > underlying structure of the decal texture on a transparent placard.
> > But there is no where to manipulate the sprite's alpha level, or
> > rather the positive image area. Instead you are relegated to create
> > large cumbersome to accomplish a simple task.
> >
> > Several things stand out:
> >
> > 1. Why doesn't the Sprite node have alpha level manipulation? In the
> > Stencil settings you can set mode to alpha but the threshold does
> > nothing. Apparently this is some sort of zpic data threshold.
> >
> > 2. Why doesn't the file node provide for alpha level manipulation? It
> > has a ton of features, cropping, image level effects, timing, etc
> etc,
> > etc. You can even blur the alpha, but nowhere can I find that it
> > provides for alpha level manipulation.
> >
> > 3. Layers are well suited to this effect but are prevented from
> > facilitating the effort by the base color. The base material
> > transparency effects the base color as well as all layers. Why can't
> > the base transparency be separated from the layer transparency? I
> have
> > been unable to determine if this is even possible, but it should be.
> > Further, Layers provide a premult switch where the base colors don't.
> >
> >
> > Ironically what is so frustrating about this is that in Maya, almost
> > every node provides the ability to manipulate alpha level, even if
> > they don't accept an alpha. And a number of real important nodes have
> > no concept on how to pass the alpha through. Really bizarre and very
> > frustrating because you have to do all these complex channel runs
> just
> > to process alpha across these nodes.
> >
> > But XSI passes alpha through just about everything without fail, yet
> > provides little to no manipulation of the alpha once injected into
> the
> > node. It's an XSI thing I suppose because most nodes do this, the
> RGBA
> > controls are off limits once data is piped into the node input
> element.
> >
> > What would be really useful however is a Levels node which allow
> > individual manipulation of the levels of all channels of whatever is
> > plugged into the node. The HLS_Adjust node is almost that node, but
> it
> > offers no control over alpha. If there was a similar node that
> > received RGBA and allowed separated gain manipulation of each channel
> > this would work well and would save a lot of needless network
> > construction just to isolate the alpha and manipulate it's level.
> >
> > I understand that a network can be created to do what I want, I just
> > think it could be easier.
> >
> > Anyway, been a long day, needed to extract this from my head LOL
> >
> > Joey
> >
> >
> >
> > Andy Jones wrote:
> >
> >> Are you using a sprite shader? If so, separate your alpha channel
> >> and multiply it by a scalar that represents the value of the overall
> >> presence of your "letter A." So, basically, you end up manipulating
> >> your alpha channel so that it ranges between 0 where there is never
> >> any image and the alpha value of the fully present part of the
> >> image. So, if it's 50% opaque, the alpha goes from 0 to .5.
> >>
> >> - Andy
> >>
> >> Ponthieux, Joey wrote:
> >>
> >>> Hello,
> >>> I have a polygon which has a texture mapped on it. The texture
> >>> has an alpha which is used to mask out unwanted areas of the image.
> >>> All unwanted areas should be transparent. I can construct this
> >>> appearance but I am finding that I am unable to fade the positive
> >>> part of the image in and out.
> >>>
> >>> For example, if I had a card, and I textured the letter A on the
> >>> card, only the letter would be visible, everything else on the card
> >>> would be transparent. Then I want to dissolve the letter in and out
> >>> at will while maintaining the base transparency.
> >>>
> >>> I have tried constant shaders, sprite shaders, layers etc. I have
> >>> manipulated mask connections, alpha connections, but still I can
> >>> find no way to accomplish this. Any suggestions would be greatly
> >>> apreciated.
> >>>
> >>
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