Question About Hair Displaying Unusual Texture Glitches

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Question About Hair Displaying Unusual Texture Glitches

Postby Schadenfreude » Wed May 20, 2020 4:10 am

Hey,

So I'm a complete XNALara noob, just trying to get into it. I had a quick question about hair textures appearing glitched and unusual. I linked to one such image below:

https://imgur.com/a/aKmvcOt

It's not only this particular model that's having the issue; a number of models I attempted to load in had similar problems.

I'm wondering if there's some setting I could adjust that would get rid of this or compensate for it? I tried googling a solution, but failed to find anything.

Thanks in advance for any help, and sorry for the newbie question!

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Re: Question About Hair Displaying Unusual Texture Glitches

Postby Ems » Wed May 20, 2020 8:09 am

Lots of models use two-sided meshes, Japanese games notoriously. Meaning whole or parts of meshes have duplicate faces, where duplicates have normals directed to the opposite side. Some engines display polygons to have only one side, one is rendered opaque and the other is transparent. Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle.

Turn on "back face culling" and "always force culling" in options to sort these out. Problem is that then you can't put models that don't require these functions on the same scene without some display oddities.

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Re: Question About Hair Displaying Unusual Texture Glitches

Postby Schadenfreude » Wed May 20, 2020 4:52 pm

Ems wrote:Lots of models use two-sided meshes, Japanese games notoriously. Meaning whole or parts of meshes have duplicate faces, where duplicates have normals directed to the opposite side. Some engines display polygons to have only one side, one is rendered opaque and the other is transparent. Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle.

Turn on "back face culling" and "always force culling" in options to sort these out. Problem is that then you can't put models that don't require these functions on the same scene without some display oddities.


Thanks for the info and explanation, I appreciate it!

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Re: Question About Hair Displaying Unusual Texture Glitches

Postby XNAaraL » Thu May 21, 2020 11:19 pm

Ems wrote:Lots of models use two-sided meshes, Japanese games notoriously. Meaning whole or parts of meshes have duplicate faces, where duplicates have normals directed to the opposite side. Some engines display polygons to have only one side, one is rendered opaque and the other is transparent. Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle.

Turn on "back face culling" and "always force culling" in options to sort these out. Problem is that then you can't put models that don't require these functions on the same scene without some display oddities.

True, turn on "back face culling" and "always force culling" (BFC/AFC) in options sort "these" out.
True, you will just replace one problem (black spots) with another problem (you can't put models that don't require these functions on the same scene without some display oddities ... except you convert the faulty model to the NGFF format )

Your explanation of what happens will be confirmed by 99.99% of all porters. However, this explanation is just a hypothetical model to describe it, like in the Atomic theory the Rutherford model is one model and the Bohr model, the Lewis model and others like the Dalton model is just a hypothetical model to describe it.

So in short:
Sure, you "model theory" can help to explain it, but is wrong in roots, if you compare it with another "true" model.
Before I will explain what really happened (next post) ... I try to list what is false:

False: "Lots of models use two-sided meshes. Meaning whole or parts of meshes have duplicate faces".
True: "Lots of models use two-sided materials. (No modeler would makes model with coplanar or coincident faces)"

False: "where duplicated faces have normals directed to the opposite side."
True: "where the polygons have the vertices (3D points) in counter-clockwise winding, and the duplicated faces have specified that the polygons have a clockwise winding ... maybe also flipped Normals"

False: "Some engines display polygons to have only one side, one is rendered opaque and the other is transparent."
True: "Is a engines display as default that polygons have only one side, then this engine have also a option to render the polygons two-sided. Even if there were an engine without this option, it wouldn't matter. The shader also has this property (CullMode = None)"

False: "Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle. Turn on "back face culling" and "always force culling" in options to sort these out."
True: "It is illogical that a visual artifact can be solved by adding additional (unnecessary) polygons and then giving the engine the command BFC/AFC to send them to the graphics card but not to draw these ployons there."

To provocate:
False: "Lots of models use two-sided meshes, Japanese games notoriously"
True: "Models, extracted by a "daemon tool" that use the wrong file format (.smd and mesh.ascii) and now not can know how to save the "Two Sided" (cm = none) state using a file format that not support this state, will produce superfluous duplicated faces, and this polygons will caust such a trouble (if the porter not remove it)."

Before I explain my "model theory" (what really happens inside XNALara or XPS), try to use your "Backface model theory" (sometimes referred to as Daltonism) and explain:
  1. Why are some spots in black (dark)? What caust the spots? Image
  2. Why have this model display oddities for (BFC/AFC) , even the "Normals" are calculated outsided? Image

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Re: Question About Hair Displaying Unusual Texture Glitches

Postby Schadenfreude » Tue May 26, 2020 1:13 am

XNAaraL wrote:
Ems wrote:Lots of models use two-sided meshes, Japanese games notoriously. Meaning whole or parts of meshes have duplicate faces, where duplicates have normals directed to the opposite side. Some engines display polygons to have only one side, one is rendered opaque and the other is transparent. Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle.

Turn on "back face culling" and "always force culling" in options to sort these out. Problem is that then you can't put models that don't require these functions on the same scene without some display oddities.

True, turn on "back face culling" and "always force culling" (BFC/AFC) in options sort "these" out.
True, you will just replace one problem (black spots) with another problem (you can't put models that don't require these functions on the same scene without some display oddities ... except you convert the faulty model to the NGFF format )

Your explanation of what happens will be confirmed by 99.99% of all porters. However, this explanation is just a hypothetical model to describe it, like in the Atomic theory the Rutherford model is one model and the Bohr model, the Lewis model and others like the Dalton model is just a hypothetical model to describe it.

So in short:
Sure, you "model theory" can help to explain it, but is wrong in roots, if you compare it with another "true" model.
Before I will explain what really happened (next post) ... I try to list what is false:

False: "Lots of models use two-sided meshes. Meaning whole or parts of meshes have duplicate faces".
True: "Lots of models use two-sided materials. (No modeler would makes model with coplanar or coincident faces)"

False: "where duplicated faces have normals directed to the opposite side."
True: "where the polygons have the vertices (3D points) in counter-clockwise winding, and the duplicated faces have specified that the polygons have a clockwise winding ... maybe also flipped Normals"

False: "Some engines display polygons to have only one side, one is rendered opaque and the other is transparent."
True: "Is a engines display as default that polygons have only one side, then this engine have also a option to render the polygons two-sided. Even if there were an engine without this option, it wouldn't matter. The shader also has this property (CullMode = None)"

False: "Putting doubles on those and flipping normals is a workaround that makes both sides visible from every angle. Turn on "back face culling" and "always force culling" in options to sort these out."
True: "It is illogical that a visual artifact can be solved by adding additional (unnecessary) polygons and then giving the engine the command BFC/AFC to send them to the graphics card but not to draw these ployons there."

To provocate:
False: "Lots of models use two-sided meshes, Japanese games notoriously"
True: "Models, extracted by a "daemon tool" that use the wrong file format (.smd and mesh.ascii) and now not can know how to save the "Two Sided" (cm = none) state using a file format that not support this state, will produce superfluous duplicated faces, and this polygons will caust such a trouble (if the porter not remove it)."

Before I explain my "model theory" (what really happens inside XNALara or XPS), try to use your "Backface model theory" (sometimes referred to as Daltonism) and explain:
  1. Why are some spots in black (dark)? What caust the spots? Image
  2. Why have this model display oddities for (BFC/AFC) , even the "Normals" are calculated outsided? Image


Thanks for the in-depth explanation, this helps a lot to explain why these texture issues exist.

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