clipka <ano### [at] anonymousorg> wrote:
> Welcome to the POV-Ray newsgroups :)
I actually already had an account (for years) I just completely forgot about it.

> Is that really what you want? I mean, the fact that you're using
> something different than OpenGL is a clear indication that you're not
> happy with the OpenGL results... or am I missing something?
I was trying to mimic the inheritance you get when using LDraw parts as they
only have one mesh per part which can be used in any color. In OpenGL this is
done by blending the triangle color with an alpha enabled texture. But reading
your comments here and on LDraw.org I think I need to look into texture_map for
that.

> In POV-Ray, layered textures do not inherit anything from other textures
> in the stack. Each has its own independent finish properties. It is also
> important to note that wherever lower layers peep through, finish
> effects such as specular highlights and reflections from both layers are
> added.
I noticed this and ended up adding info on png's being transpaent or not to
generate different kinds of (layered) textures.

> Layered textures therefore tend to be difficult to control. If possible,
> I'd recommend using texture maps (they tend to be slower though). You
> can use the alpha channel of an image to choose between two textures,
> and then use the colour channel of the same image for one of them. Let
> me know if you need help with the details.
Thanks I'm going to look into that.

> That said, maybe I can add a switch to layered textures in POV-Ray that
> would cause the alpha channel of a layer to knock out not only that
> layer's diffuse component, but also highlights and reflection. I guess
> such a switch might come in handy for non-LDraw users as well.
That would be very helpful especially when coming from an OpenGL background.

>
> I hope I am making sense to you, and am barking up the right tree. If
> not, let me know.
Yes very much so, thanks.


> > http://forums.ldraw.org/thread-21710-post-23886.html#pid23886
>
> Looks pretty convincing to me. What bothers you about it specifically?
Mainly the fact the non transparent part of the image_map isn't transparent on
transparent part usage. The difference being patterns painted on transparent
plastic or them being part of the transparent plastic. I think both situations
can appear in real LEGO though so I'm not sure which one is correct. But for now
I want them to be the same as much as possible.

But I suspect texture_map can solve that too.

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