Referring to some figures having a single plane for transmapped per upper/lower lash geometry (eg Antonia) and others having 2 planes layered for said geometry (V4, La Femme)...

I personally haven't seen a significant difference but am curious if Poser users have a preference one way or the other. I imagine that doubled layered has more morphing options, such as thickness or irregularity, but wonder how many actually take advantage of such a thing outside of lash length in terms of spinning dials. Seems to be density can easily be handled by the maps.

Nevermind.

Double layered just in case.

I read somewhere that most people's lashes grow in a single row, and having two or more rows is an anomaly, but I don't know if that's actually true or just some nonsense the internet made up. That said, there would certainly be some variation in the direction they grow in, which two planes at a slight angle to each other might help capture. All theoretical, all course, I haven't tried out anything like that in practice.

odf posted at 6:07 PM Sun, 16 April 2023 - #4462393

I read somewhere that most people's lashes grow in a single row, and having two or more rows is an anomaly, but I don't know if that's actually true or just some nonsense the internet made up. That said, there would certainly be some variation in the direction they grow in, which two planes at a slight angle to each other might help capture. All theoretical, all course, I haven't tried out anything like that in practice.

I was leaning toward a single curved plane for upper and lower, a multi stage edge extrude and extraction followed by a slight curve added with sculpting tools and a final additional subdivision. Antonia seems to get by just fine with a single mesh for each. I ended up going double layer for the top (duplicate, slight translate), single for the bottom. Similar to LF. It only takes a couple of minutes to add the additional so I figured what could it hurt... it seems the typical practice. I waited the last minute to do it so now I'll have to merge with and regroup the head to include the lashes, no biggie. Easy stuff.

...

It's true, that little bit of extra geometry won't hurt anyone. For my lashes, of course, you'd need three or four planes top and bottom, but I'm apparently a freak. :-)

I think double layers would be cool for having like FX for the lashes, extra transparencies, etc.

Older figures had double layered lashes for FireFly and OpenGl compatibility.

Superfly will do double sided materials without issue, so one lash layer works fine in that. 

If you build a figure that will be used in FireFly it is best to have two layered lashes.

shvrdavid posted at 12:18 AM Wed, 26 April 2023 - #4463422

Older figures had double layered lashes for FireFly and OpenGl compatibility.

Superfly will do double sided materials without issue, so one lash layer works fine in that. 

If you build a figure that will be used in FireFly it is best to have two layered lashes.

I see now. It's weightmapped so anyone using it with Firefly would, predictably, more than likely also have the options of normals forward (Firefly) and show backfacing (openGL) at their disposal. In any case the normals are congruent in both layers, same facing. Makes me wonder if I should cull those polys or flip the normals in the the upper layer. I haven't reached the morphing stage with the head so an edit wouldn't have impact really (at least as far as vertice number, winding order would remain to be seen)... I'm inclined to leave it.

Thanks for clearing up that mystery shvrdavid.

Maybe a slight offset of the upper a bit closer to the lower and baked state into the referenced obj is in order though, woolgathering.

Thanks again.

Firefly and OpenGl do indeed have normals forward but neither have double sided materials in Poser. 

As an example, if all you have is normals forward on one layer, you will never see all of the lashes from a side view simply because that setting is material wide in FireFly and OpenGl. You may need to literally see the front and back of the lashes at the same time because of the curvature of the lashes and the angle you are looking at them. And you need two layers to do that in Firefly. One facing each direction, with normals forward turned off on the material. Turning normals forward on with two layers can put you right back to appearing to only having one layer. Which is obviously not what you want.

Show back facing polygons is a bit different than you might first think. Show back facing does not flip normals or make the material double sided. It is z culling based on the shader, basically just like older 32 bit video games used to save memory. It is kind of a moot point now that Poser is 64 bit anyway. But still presents issues in Firefly if culling is on. The key to z culling, is the shader used.

The geometry has to be there for certain things to work. You obviously need them for reflections, or things will look very odd. You also need the geometry behind it if transparency or translucency is in the shader, which is an example of when the backside geometry is never culled, even if it is turned on in the render engine.

I hope I explained that right, lol....

Well, that was enlightening. Thanks, shvrdavid!

After looking at the lash designs of several figures, and in light of what shvrdavid has stated, I have to admit I'm a bit confused.

La Femme has double layered lash design. That is 2 one sided planes with the normals pointing in the the same directions in both planes.

V4's lash design amounts to the same. Congruent normals.

Aiko 3 also has duel layered lashes, normals pointing in the same directions in both layers.

Posette has manifold lashes. That is a single lash geometry with thickness, enclosed. Similar to a toon type lash.

The question is, going back to A3 (gen3 daz meshes), if the double layer was intended for the renderer to discern the visibility of the lashes wouldn't that have required each layer to have normals at opposite directions rather than same facing?

Which leaves the question why duel layer lashes are still a practice if in each instance the normals are congruent across top and bottom layers.

Just trying to discern why this is the actuality in relation to the reasoning posited by shvrdavid. Am I missing something?

Example:

Aiko 3 (at this point an old figure, certainly firefly and 32 bit times)

Her top lashes (duel layer one sided planes) separated from her head and slightly offset from each other, Display face normals. Both layers have normals oriented in the same direction...

What you have discovered, is that not everyone realized why there were 2 layers to lashes.....

shvrdavid posted at 3:46 PM Sat, 29 April 2023 - #4463753

What you have discovered, is that not everyone realized why there were 2 layers to lashes.....

Lol. 👍

I'll break the cycle of misinterpretation then, a minor detail that virtually no one will notice :)

I would be curious to see a figure that got it right though, if such exists historically.