alpha texture

[Carrie Galaga]

Hi 

this is a question about the alpha texture.

for example : hair

I put alpha texture on hair object.

abnormality is seen in the part that it overlaps...

hair behind becomes completely transparent.

I tried much hair

but I found the hair which did not appear of such a symptom.

why do these hair not have abnormality of alpha?

special texture?　upload setting?　method of fabrication?

(I use Blender)

Please tell me the solution

Sorry for being bad at English

 

 

 

[Wulfie Reanimator]

Alpha-on-alpha or "alpha-sorting" is a common problem in 3D rendering. The geometry typically used for hair is very difficult to "sort" (to find out which texture is in front of the other) and when it goes wrong, you see the issue. The texture that is behind was mistakenly placed in front, so it disappears.

To fix it, you need to use fewer alpha textures, use alpha in smaller areas, or just hope for the best.

Sometimes, alpha-sorting just works. Sometimes, the same hair will have issues. Sometimes, selecting the hair will fix some of the issues.

[Ardy Lay]

Engineer the object geometry so that the means of the faces with transparency are always placed in the z-buffer in the order that provides the desired appearance.  

[Kyrah Abattoir]

Trying to avoid overlapping alphas is a common game design problem.

You don't need to heavily overlap alphas to make good looking hair, if you do it just means you're doing it wrong.

Remember that Game modeling isn't so much about reproducing reality accurately, but about giving the illusion that you did and do it cheaply.

[Cyrule Adder]

 

This is a common problem. Unlike other geometry, anything set with Alpha Blending cannot benefit from the Zbuffer, which determines the rendering order of solid polygons, and to tell the render what to part of a mesh to skip. Instead what happens is your solid geometry is rendered first (Front to back). Then your alpha meshes are rendered from back to front as best as possible. The problem here is that it's not easy to figure out what is considered to be in front, or behind. This is because one mesh could be "in front" at multiple angles, with an object in between. So you get a Z-fighting issue. Which is where it looks like something is popping back and forth. Or something completely disappears.

Alpha Blending is intended for things with significant transparency.

 

Ultimately, the best fix is to use Alpha Masking, instead of Alpha blending. Alpha Masking will still make use of the Zbuffer, eliminating any of the Z-fighting issues. The difference here is that where you can have soft smoke with Alpha Blending, you cannot emulate this with alpha masking. Alpha Masking says it's either completely invisible, or it's completely solid at this pixel.

Edited August 15, 2020 by Cyrule Adder

[Carrie Galaga]

Wulfie, Ardy, Kyrah, Cyrule thank you for your advice.

 

I changed the setting to solve Z-fighting.

this is effective in Blender, but is not reflected in SL in-world...

I do not make rendering.

 I understand the difference between Alpha  Masking and Alpha Blending.

 

When I make it,

 show texture on the both sides using "Solidfy" or NOT?  or mixes these?

I try such a work.

but my problem has not been fixed...:'(

Edited August 16, 2020 by Carrie Galaga

[Cyrule Adder]

7 hours ago, Carrie Galaga said:

Wulfie, Ardy, Kyrah, Cyrule thank you for your advice.

 

I changed the setting to solve Z-fighting.

this is effective in Blender, but is not reflected in SL in-world...

I do not make rendering.

 I understand the difference between Alpha  Masking and Alpha Blending.

 

When I make it,

 show tex tea on the both sides using "Solidfy" or NOT?  or mixes these?

I try such a work.

but my problem has not been fixed...:'(

Solidify would not be the correct modifier. You'll want to use "Make Double Sided"

And the reason why it's not reflected in Second Life, is you did not change the settings to help resolve the Z-fighting issues in SL. Additionally, SL's Alpha blending has well known to be kinda *****.

[Carrie Galaga]

thank you @Cyrule Adder

I heard "Make Double Sided" for the first time.

Will it be such a thing?↓↓

https://www.katsbits.com/tutorials/blender/double-sided-faces-different-materials.php

I want to try it later

and check Z-fighting issues sequentially.

Please tell me if there is a site serving as a reference

 

 

 

Edited August 16, 2020 by Carrie Galaga

[n0minous]

19 hours ago, Cyrule Adder said:

Solidify would not be the correct modifier. You'll want to use "Make Double Sided"

And the reason why it's not reflected in Second Life, is you did not change the settings to help resolve the Z-fighting issues in SL. Additionally, SL's Alpha blending has well known to be kinda *****.

I think Double Sided only works in Blender though or at least collada doesn't seem to support exporting double sided materials. Also, aren't SL's backfaces always transparent? I might be wrong since I've only researched forum posts from like 2012.

@Carrie Galaga This post describes duplicating a plane and flipping the normals so that the texture appears on both sides. Idk if you have to move them apart to avoid Z-fighting, but he doesn't seem to for leaves.

 

[Carrie Galaga]

@n0minous thanks for advice

I made hair-parts using "Solidfy" (both sides texture) and only for one side hair-parts

I try making of the hair which mixed these now

 

but very peculiar...

some hair designer [ex] [ex] [ex] uses Alpha Blending  well

 

[n0minous]

Yw, you could try using alpha blending and alpha masking for different layers of hair or reordering the vertex indices as recommended in this thread  . If you haven't already, I suggest using the forum's search function since a lot of solutions to common questions are available.

Edited August 16, 2020 by n0minous

[Kyrah Abattoir]

1 hour ago, n0minous said:

you could try using alpha blending and alpha masking for different layers of hair

While this is something i've seen other creators do, That's just cramming in more polygons rather than fixing the underlying design problem, alpha blending layering issues have existed since the dawn of 3D games, this isn't new or specific to SL. As a creator it is your job to avoid creating situations where it becomes visible.

Good hair design doesn't need heavily layered alpha blended strands, that's the hallmark of someone piling crap together until it looks right. And I know because that's what I (and everyone else who made prim hair) used to do before I decided hair creation wasn't something I was gonna focus on.

[Wulfie Reanimator]

4 hours ago, Carrie Galaga said:

some hair designer [ex] [ex] [ex] uses Alpha Blending  well

Looks pretty "normal" to me.

[n0minous]

@Kyrah Abattoir I don't have any experience creating hair cards and I just wanted the OP to know the importance of searching forums for info since many solutions can be found by digging. I was a bit too hasty in finding a good solution this time, though. By delving more, I was able to find a goldmine and it seems that using alpha blending only for the tips of hair that require translucency is best in order to minimize sorting issues:

Ofc creating hair cards that both avoid sorting issues and create the illusion of volume can take a long time to master. I didn't mean to say that you can just layer cards on top of each other willy-nilly and I apologize if it sounded that way.

[Cyrule Adder]

6 hours ago, n0minous said:

@Kyrah Abattoir I don't have any experience creating hair cards and I just wanted the OP to know the importance of searching forums for info since many solutions can be found by digging. I was a bit too hasty in finding a good solution this time, though. By delving more, I was able to find a goldmine and it seems that using alpha blending only for the tips of hair that require translucency is best in order to minimize sorting issues:

Ofc creating hair cards that both avoid sorting issues and create the illusion of volume can take a long time to master. I didn't mean to say that you can just layer cards on top of each other willy-nilly and I apologize if it sounded that way.

Well... there are tools to help you do that. But if you don't want to bash your brains out by attempting to wrangle a mixture of Alpha masking, and blending. What you can do is you can paint your hair cards in photoshop with a "softish" brush in the alpha channel. When I say "Softish" I mean there's a very clear dark zone, and soft fuzzy edges that spans out a good ways.

When you run alpha masking, you will usually be asked about an "alpha-cutoff". A typical alpha texture runs from 0 transparency to 100. The cutoff selects from zero, all the way up to the point you've marked. But here's the magic. Due to the way the GPUs work, textures are sampled, and many times these values will get blended. What will happen is the alpha will be anti-aliased. Assisting in making it look cleaner.

[Kyrah Abattoir]

14 hours ago, n0minous said:

@Carrie Galaga This post describes duplicating a plane and flipping the normals so that the texture appears on both sides. Idk if you have to move them apart to avoid Z-fighting, but he doesn't seem to for leaves.

you have to make sure they will triangulate the same way too or it can look weird.

[Carrie Galaga]

@n0minous @Kyrah Abattoir @Cyrule Adder @Wulfie Reanimator

thank you for important advice

I will try it based on the advice of you in various ways:)

but it will take time a little as I am inexperienced...

please give me a little more time

I report progress again

Edited August 17, 2020 by Carrie Galaga