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Backfacing normals
Posted: 18 November 2012 02:20 PM   [ Ignore ]
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If I make an object that is only one plane one side will have normals facing out (light side) and the other side will have backfacing normals (dark side).

I asked a friend about this and she said:

In Modo, in the Paint tab (the equivalent of Poser’s material room) there is a checkbox under each material that says “Double-Sided”. If you check this, it -will- double the number of polygons for that material -but- it will also make it so that there are no backfacing polys: the material can be viewed from both directions.

My question is whether there is an equivalent in Hexagon.

If I make one plane objects then they have a dark side when used in DS and Poser.

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Posted: 18 November 2012 03:30 PM   [ Ignore ]   [ # 1 ]
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There’s nothing you can do in Hex that will make DAZ and Poser render backfacing polys.  There are some different possible solutions.


-Make a liner or another layer of polys facing the other way.  This is not going to do well on Genesis clothes most of the time because of smoothing.  Sometimes it worked with the Gen 4’s and sometimes would self-clip.
-Light or render them with multiple lights, not just UberEnvironment light+specular.  The more complex the lighting setup, the less dark and opaque the backfacing polys will look.
-Use an Uber shader and the Translucent option.  This is tricky to work with.


Most often when modeling with DAZ and Poser in mind, you use a single poly sheet only when it will only be viewed exclusively from one side.  If you’re making props that are meant to be seen from both sides, you need to add the opposite-normal poly layer.  If you can share what type of item it is, I might be able to help more.

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Posted: 18 November 2012 05:11 PM   [ Ignore ]   [ # 2 ]
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Hi, thanks for the info. 

What I’d like to do (but thinking I can’t) is make a round/circular plane and apply a transmap to it so that it looks very lacy.  If I do this it will look ok from the front but from behind it will look dark.

I thought about making a very small thickness or a second plane but getting them exact in Hex’s uvmapping would be an all day effort and probably not work.  Both surfaces would have to be aligned exactly to get a transmap that looked clean and sharp when used.

I hope that’s clear.  Let’s say I want to put a snowflake transmap on the circular plane.  If I had two planes they would have to be exactly aligned so that the snowflake didn’t look blurry.  Is this clear?

I use Hexagon to do all my uvmapping even though it is not the best at it.  I don’t know how to make UVmapper add seam breaks like Hex does.  Hex is really simple to do that but the results are terrible quite often.  I wish Daz3D would step up their updates on this excellent software.

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Posted: 18 November 2012 05:15 PM   [ Ignore ]   [ # 3 ]
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I’m unfamiliar with Hex’s specifics.  Can you not create your round plane, UV map it, then dup the plane and flip the normals with it still being part of the main object?  In Blender that’s like five minutes’ work, and the UVs would be perfectly aligned.

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Posted: 18 November 2012 06:07 PM   [ Ignore ]   [ # 4 ]
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Yes, I think I can do that.  What a wonderfully simple solution.  I’m embarrassed that I didn’t think of it.

I was once told that Blender was easy to uv map in so I downloaded it and took a look.  Hexagon and Blender seem to be similar in the way they uvmap. Of course I didn’t delve deeply into because I would have had to spend hours or days trying to learn it.  Maybe I didn’t give it a chance.  Or am I confusing Wings3D with Blender?

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Posted: 18 November 2012 06:13 PM   [ Ignore ]   [ # 5 ]
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No idea. :D I don’t know what Hex can and can’t do with UVs.  Blender allows pinning, live unwrap, selection of vert loops in the UV window, proportional editing, and alignment of any given set of verts on either axis, which are the features I use the most often.  The ability to turn on syncing so you can select any given verts or faces in the 3d window and see where they fall on the UV (and vice versa) is a pretty huge feature for me as a clothing maker.


I know Hex can do seams but I don’t know how much it lets you manipulate things in the UV itself. Blender allows pretty much ultimate control over that.  I think I’ve heard that Hex has an equivalent to Blender’s mirror modifier, but I don’t know if it can apply mirrored UVs that way or not (Blender can).

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Posted: 18 November 2012 09:42 PM   [ Ignore ]   [ # 6 ]
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Hexagon does some of what you mention and some I don’t know what it is so don’t know if Hexagon does it or not.  It’s got pinning, selection of vert loops in the uv window and you can select vertices/faces/points from either the 3D window or uv window.

One thing that it doesn’t do (and I wish it would) is to maintain vertices relative to one another when you are straightening many lines at once.  Hexagon will straighten them until they are just one line.  If you grab all the horizontal lines in a square map and want to straighten them,  they will smoosh down into one line.  I have to do this all one by one.  In better softwares you can straighten them all at once and they will stay in their relative positions. 

If Blender can do that, please, please let me know.  Thanks.

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Posted: 18 November 2012 09:47 PM   [ Ignore ]   [ # 7 ]
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I think you’d still have to do it a vert loop at a time.

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Posted: 18 November 2012 11:08 PM   [ Ignore ]   [ # 8 ]
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Just trying to figure out what you guys mean by placing a texture on a single-thickness plane and not being able to see the reverse?

This is a single poly, mapped and textured - the duplicate is flipped 180 degrees to see the back - no problem.

Hexagon’s UV mapper can do most of what Blender can, except mirror UV’s.  Even a sophisticated mapper like UU3D can’t straighten out a multiple selection of edges without collapsing them into a single line - at least, I haven’t found a method of doing so:)

Wings 3D can.

I don’t personally use Hex’s UV mapping on complex meshes for two reasons - one because it doesn’t remember seams and pins after saving and opening, so that has to be a single-session operation and secondly, because it fits everything onto the grid and has no idea of proportions.  It will often give an insignificant part of the map prominence and squash down the major parts, so you have to eyeball proportions.

Other than that, it does do a pretty good job of unwrapping if you place your seams and pins correctly.

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Posted: 18 November 2012 11:14 PM   [ Ignore ]   [ # 9 ]
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Roygee - 18 November 2012 11:08 PM

Just trying to figure out what you guys mean by placing a texture on a single-thickness plane and not being able to see the reverse?

This is a single poly, mapped and textured - the duplicate is flipped 180 degrees to see the back - no problem.

And it’s is in Hexagon.  DS/Poser are the issue here as they will not do that - with UberEnvironment lights on the backfacing will be black.  Using a complex light set with a non-UE diffuse shadowcaster helps but doesn’t eliminate the darkening of the backfacing side.

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Posted: 19 November 2012 01:09 PM   [ Ignore ]   [ # 10 ]
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I have two-sided lighting turned off in preferences for Hexagon so that I can always see backfacing polys.  If you turn off your two-sided lighting the reversed plane will look darker in Hexagon than the original.  As SickleYield says, you can see the texture in Hexagon fine and the texture even shows up in DS and Poser but the backfacing polys will be much darker in color and with certain lighting they will look black.  Just not good for product creation.

I used SY’s suggestion and I got Hexagon going squirrely trying to show backfacing and forward facing polys at the same time so I moved the duplicated surface .002 away from the original.  that worked fine.  Both in the same space might have worked in Poser but I probably would have gotten some dark areas showing through so I moved it a tad.

@SY, I believe it was in a video I watch of Modo or 3DSmax that I saw the lines all straightened at the same time but they stayed in their relative positions.  I remember thinking how cool that was and would love for Hexagon to do it. 

Why don’t I move away from Hexagon and learn something else?  Because it took me forever to learn Hexagon as it was (and still learning).  I have had Blacksmith3D for months and still can’t use it for what I needed it for.  I had Poser6 for 2 years before I ever made my first render (didn’t help that I was a DS/Bryce user).  I am a very slow learner if I don’t have a teacher.  Learning on my own is torcherous as I have so many questions.  Ack

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Posted: 19 November 2012 01:16 PM   [ Ignore ]   [ # 11 ]
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Burpee - 19 November 2012 01:09 PM

I used SY’s suggestion and I got Hexagon going squirrely trying to show backfacing and forward facing polys at the same time so I moved the duplicated surface .002 away from the original.  that worked fine.  Both in the same space might have worked in Poser but I probably would have gotten some dark areas showing through so I moved it a tad.

@SY, I believe it was in a video I watch of Modo or 3DSmax that I saw the lines all straightened at the same time but they stayed in their relative positions.  I remember thinking how cool that was and would love for Hexagon to do it. 

Why don’t I move away from Hexagon and learn something else?  Because it took me forever to learn Hexagon as it was (and still learning).  I have had Blacksmith3D for months and still can’t use it for what I needed it for.  I had Poser6 for 2 years before I ever made my first render (didn’t help that I was a DS/Bryce user).  I am a very slow learner if I don’t have a teacher.  Learning on my own is torcherous as I have so many questions.  Ack

Yes, sorry, you do want it translated a teensy bit.  I forgot to mention it.


I’ve heard Modo is used by a lot of DAZ artists, but I haven’t tried it.  I hate Max’s interface with a burning passion.  But then, Blender was my first 3d program, and it’s ninety degrees off from anything else in terms of interface.  My current plan is to add Zbrush to my existing workflows the next time I get a big enough payout.

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Posted: 19 November 2012 06:27 PM   [ Ignore ]   [ # 12 ]
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Also, if you use area lights or convert an object (primitive) for use as a light source in Lux/Reality, you have to pay attention to this, too..because the light is emitted from the ‘front’ side. 

That was something that I had forgotten about when I recently tried to do render in Lux, with geometry lights…my light was coming from the wrong direction (it was going up, instead of down)...

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Posted: 19 November 2012 09:24 PM   [ Ignore ]   [ # 13 ]
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Regarding “double sided polygons”...

This is done with the click of the mouse in UVMapper pro, but UVMapper classic (the free version) has no such capability.

But knowing how double-sided works, I decided to do an experiment using UVMapper classic and damned if it didn’t work!!!

Here’s how I did it:

Select a model. Let’s call this model “mesh1”.

Load “mesh1” into UVMapper classic.

Immediately resave the model as say, “mesh2” using the following parameter: In the “OBJ Export Options” the ONLY box you want checked is “Reverse Winding Order”.

Close UVMapper classic.

Open Hexagon and load/import both “mesh1” and “mesh2”.

If you look at mesh2 by itself, you’ll see that the mesh is “inside out”. This is what we want.

Select both mesh1 and mesh2 and then hit “weld”.

Saving this as say, “mesh12” gives you a doublesided version of the original mesh1.

CAUTION:
If mesh1 was previously UV mapped, welding mesh1 and mesh2 destroys it so that “mesh12” must be remapped again.

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Posted: 19 November 2012 10:37 PM   [ Ignore ]   [ # 14 ]
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Clever:)

But then you get those horrible rendering artifacts when facets share the same space - unless you offset, in which case you could just as well have given it thickness:)

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Posted: 19 November 2012 11:12 PM   [ Ignore ]   [ # 15 ]
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Roygee - 19 November 2012 10:37 PM

But then you get those horrible rendering artifacts when facets share the same space - unless you offset, in which case you could just as well have given it thickness:)

Yesssssss…..!!  smile

For instance, Poser goes REALLY bananas when I try to use doublesideds with transparency. I think this is because Poser defaults to rendering both sides of the polys and gets confused trying to paint 2 different images in the same space. Oddly, Poser’s preview doesn’t show backfaces so a model can be seen “inside out” (and doublesideds are seen “correctly” from either side), but both the “poser 4” and the “firefly” renderer DO render backfaces, so Poser “sees” 4 different surfaces occupying the same plane on any doublesided poly.

It doesn’t like that.  smile

ADD:

Hold da’ phone!

I just brought up Poser to see if there was an option to disable backfaces, and in “firefly” there is, called “remove backfacing polys”.  The “Poser 4” renderer has no such option.

Maybe I’ll go looking for the “fairywings” I made long ago which uses the partially transparent doublesided polygons that caused me the above problems and see if rendering them in firefly with backfaces disabled helps the matter any.

 

 

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