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Extension for material properties? - N. W. Perry - 2020-09-30

I had this topic in mind, when I stumbled on this very old thread. With the vastly increased use of photo-realistic rendering since then, I'm wondering if the subject has been given any more thought?

In particular, I've found that there's a fair number of parts that are made of a softer plastic than the typical ABS brick, and/or have a rougher, matte finish (like the slope texture that kicked off that thread). While there are already color categories for rubber, various metals, etc., there seems to be a lack of options for describing different solid plastic properties within LDraw.


As a more general note, this seems like another in a family of physical part characteristics that I could envision being described by a series of metadata extensions, possibly as part of a hypothetical LDraw 2.0. Others in the family could include snapping/connectivity info, physical part dimensions (for accurately rendering seams, or calculating part collisions), and kinematic info (for describing technical functions like gear meshes).


RE: Extension for material properties? - Gerald Lasser - 2020-09-30

Yes, I agree, it is about time to pick this topic up again after 9 years.

Especially when I did now the Technic Panels of the Lamborghini I noticed this with the test renders again they are too shiny when rendered with Stud.io

concerning Studio, they do have a small shadow library, e.g. for some slopes, where they add the typical pattern. I think they take the LGEO data for that.


RE: Extension for material properties? - Magnus Forsberg - 2020-09-30

(2020-09-30, 21:13)Gerald Lasser Wrote: Yes, I agree, it is about time to pick this topic up again after 9 years.

But I think we all agreed on that no added info should be forced into the dat-files.
We don't want to recycle any file to add any metadata info.


RE: Extension for material properties? - N. W. Perry - 2020-09-30

(2020-09-30, 21:24)Magnus Forsberg Wrote: But I think we all agreed on that no added info should be forced into the dat-files.
We don't want to recycle any file to add any metadata info.

Yeah. By "metadata" (and perhaps I'm misusing the term), I mean something separate and apart from the "data"—just as shadow libraries are now used. A user could add the info to any part, either in a joined file or by appending the .dat file itself, but no .dat would be made non-compliant by not having it.


RE: Extension for material properties? - Willy Tschager - 2020-10-03

(2020-09-30, 21:24)Magnus Forsberg Wrote: But I think we all agreed on that no added info should be forced into the dat-files.
We don't want to recycle any file to add any metadata info.

We never agreed if information should be stored in a parallel library or just one file:

https://news.lugnet.com/cad/?n=11226

and we never will. I gave up on the topic and you should do the same.

w.


RE: Extension for material properties? - Orion Pobursky - 2020-10-03

(2020-10-03, 8:05)Willy Tschager Wrote: We never agreed if information should be stored in a parallel library or just one file:

https://news.lugnet.com/cad/?n=11226

and we never will. I gave up on the topic and you should do the same.

w.

I really think we should pull in and officialize (or, at least, officially bless) all the common meta commands (snapping, flexible parts, and instructions) and Roland's shadow library.


RE: Extension for material properties? - Gerald Lasser - 2020-10-03

I actually like the proposal in the "very old" thread, i.e. having a material start meta and end meta.

I got now the Trolls container, which is opaque on the outside, i.e. slightly rough, but on the inside it is shiny ABS. That's not a simple material property that can be applied to the part in general.

Some materials are covered by assigning a special color, like Rubber or metal


RE: Extension for material properties? - Roland Melkert - 2020-10-03

(2020-10-03, 18:44)Gerald Lasser Wrote: I actually like the proposal in the "very old" thread, i.e. having a material start meta and end meta.

I got now the Trolls container, which is opaque on the outside, i.e. slightly rough, but on the inside it is shiny ABS. That's not a simple material property that can be applied to the part in general.

Some materials are covered by assigning a special color, like Rubber or metal

We already have a material start/end meta (sort of), it's called the texture extension.

It just needs some changes to make it work with in a different mode.

Maybe introduce a new meta name which is backwards compatible with the texture one. So parsers don't need to support jet another begin/end/next mechanism.  They would only need to disable part of it's parameter handling etc when the meta is called texture instead of e.g. 'material'


RE: Extension for material properties? - Philippe Hurbain - 2020-10-04

(2020-10-03, 19:18)Roland Melkert Wrote: We already have a material start/end meta (sort of), it's called the texture extension.
It just needs some changes to make it work with in a different mode.
Maybe introduce a new meta name which is backwards compatible with the texture one. So parsers don't need to support jet another begin/end/next mechanism.  They would only need to disable part of it's parameter handling etc when the meta is called texture instead of e.g. 'material'
Then there is a need for some nesting, which is currently excluded from texmap specification: eg. we need to be able to apply texmap pattern on grainy slopes (BTW, what happens in various implementations if we try to apply texmap on something containing a subpart itself texmapped?)

Speaking of materials, we still don't have satisfying way to use texmap patterns containing metallic inks...


RE: Extension for material properties? - Magnus Forsberg - 2020-10-04

(2020-10-03, 18:44)Gerald Lasser Wrote: Some materials are covered by assigning a special color, like Rubber or metal

How many of these properties could be placed in ldconfig?
IMO we are missing colour codes and properties on textile materials.