Extension for material properties?


Extension for material properties?
#1
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).
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RE: Extension for material properties?
#2
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.
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RE: Extension for material properties?
#3
(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.
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RE: Extension for material properties?
#4
(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.
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RE: Extension for material properties?
#5
(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.
LEGO ergo sum
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RE: Extension for material properties?
#6
(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.
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RE: Extension for material properties?
#7
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
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RE: Extension for material properties?
#8
(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'
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RE: Extension for material properties?
#9
(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...
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RE: Extension for material properties?
#12
(2020-10-04, 7:00)Philippe Hurbain Wrote: Speaking of materials, we still don't have satisfying way to use texmap patterns containing metallic inks...

Well actually we do: Gloss Map. But I don't know if any of the editors support it.
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RE: Extension for material properties?
#10
(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.
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RE: Extension for material properties?
#11
(2020-10-04, 8:07)Magnus Forsberg Wrote: How many of these properties could be placed in ldconfig?
IMO we are missing colour codes and properties on textile materials.
IMHO linking material (eg. rubber) to color was a kludge and it would be better to find another way...
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RE: Extension for material properties?
#13
(2020-10-04, 8:23)Philippe Hurbain Wrote: IMHO linking material (eg. rubber) to color was a kludge and it would be better to find another way...

Is there anything saying LDconfig is only for colors? Or could it contain one section for colors, and another for materials/finishes?
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RE: Extension for material properties?
#14
(2020-10-04, 14:09)N. W. Perry Wrote: Is there anything saying LDconfig is only for colors? Or could it contain one section for colors, and another for materials/finishes?
Problem is not so much defining material than to use it. Basic LDraw syntax has a color property, but no material one...
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RE: Extension for material properties?
#15
(2020-10-04, 14:27)Philippe Hurbain Wrote: Problem is not so much defining material than to use it. Basic LDraw syntax has a color property, but no material one...

I guess materials would be called by the syntax of the !MATERIAL (or !TEXTURE) meta.

Or maybe they could be called by the existing color property, using some kind of prefix system. E.g., color code 16 would be main color with no material specified, but 1600101 could be main color with a rubber finish, 1600201 would be main color in a slope texture, etc.  (Or use letters for material codes, or a character separator.)
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RE: Extension for material properties?
#16
(2020-10-04, 21:52)N. W. Perry Wrote: Or maybe they could be called by the existing color property, using some kind of prefix system. E.g., color code 16 would be main color with no material specified, but 1600101 could be main color with a rubber finish, 1600201 would be main color in a slope texture, etc.  (Or use letters for material codes, or a character separator.)

I like this idea.

We could reuse one of the 'useless' color ranges (like the invisible ones).
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RE: Extension for material properties?
#17
(2020-10-05, 18:02)Roland Melkert Wrote: I like this idea.

We could reuse one of the 'useless' color ranges (like the invisible ones).

I like this since it allows legacy software to be able to use a new ldconfig.ldr and default to still show colors correctly.

You and me might like this because it is neat because we see masks with the possibility of describing surfaces. However. I fear that we might make it too difficult for less technically inclined users.

For this reason I also want us to consider META statements, such as something like this impacting the next line:

0 !SURFACE [ROUGHNESS=0.8] [OTHER_FEATURE=VALUE] ...
1 2 0 0 0 1 0 0 0 1 0 0 0 1 subfile.dat
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RE: Extension for material properties?
#18
(2020-10-05, 22:00)Lasse Deleuran Wrote: I like this since it allows legacy software to be able to use a new ldconfig.ldr and default to still show colors correctly.

You and me might like this because it is neat because we see masks with the possibility of describing surfaces. However. I fear that we might make it too difficult for less technically inclined users.

For this reason I also want us to consider META statements, such as something like this impacting the next line:

0 !SURFACE [ROUGHNESS=0.8] [OTHER_FEATURE=VALUE] ...
1 2 0 0 0 1 0 0 0 1 0 0 0 1 subfile.dat

My sense is that the technical difficulty of using a meta command vs. editing the config to include a new color/finish/material is approximately equal. So whatever solution gets the job done while meeting all the needs of an LDraw specification is probably best.

(And of course, the ldconfig is really just a bunch of meta commands anyway…)
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RE: Extension for material properties?
#19
(2020-10-05, 18:02)Roland Melkert Wrote: I like this idea.

We could reuse one of the 'useless' color ranges (like the invisible ones).

One problem with this is that the material is then tied to a specific color. So, you then need to have a separate entry for every combination of color and non-standard material.
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RE: Extension for material properties?
#20
(2020-10-08, 0:45)Travis Cobbs Wrote: One problem with this is that the material is then tied to a specific color. So, you then need to have a separate entry for every combination of color and non-standard material.

It should work the opposite way. If "1600101" refers to main color with a rubber finish, all you'd need to do is create the entry for rubber finish under 00101. The prefix would always be an existing color code, so the only entries you'd need to create are the materials.
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RE: Extension for material properties?
#21
(2020-10-05, 18:02)Roland Melkert Wrote: I like this idea.

We could reuse one of the 'useless' color ranges (like the invisible ones).

What needs to happen next, if we want to go forward? (Just to keep the idea alive.)  Wink
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