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Need help with alpha blending issues.


ReinaLexigle
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Hello to everyone

I'm facing problems with alpha blending in fitted hair.

here is my model rezzed in the ground with no
glitch .

1.thumb.png.4827d528446bac26eefe93bf3771e7ef.png


but when attached to the avatar look some faces
missing.

2.thumb.png.80b97870e60c1881abc12a9e4993d0da.png

 

I hope to find a solution for this issue but  i would
rather not have to use alpha masking on it

we have a lot of exemples of hair store that use
alpha blending without any issue like Doux hair or
little bones ecc.in your opinion how they avoid that
problem.

Any help or advices will be appreciated ,thank you.

NB: I'm using maya as programm and rigging in mayastar.

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1 hour ago, ReinaLexigle said:

we have a lot of exemples of hair store that use
alpha blending without any issue

Which doesn't mean that is the right thing to do. Alpha blending should be used sparingly and avoided as much as possible, as it is heavier to render. Ah yeah, I know... Who cares about that... 

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58 minutes ago, OptimoMaximo said:

Which doesn't mean that is the right thing to do. Alpha blending should be used sparingly and avoided as much as possible, as it is heavier to render. Ah yeah, I know... Who cares about that... 

HI thank you for the input

yes you're right alpha blending should be used sparingly and avoided as much as possible , my problem is i have to understand the use of alpha masking ,i cant find any help in web ,i still have that jagged texture not a smooth one.

i heared about the vertex ordering can help to resolve that problem but Unfortunately the earlier versions of maya doesnt have that option.

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15 minutes ago, Profaitchikenz Haiku said:

Just thinking that if they'e dipping into onion layers there could be some confusion as to which to render, the hair of the onion layer.

hi and thank you

they are not dipping into onion layer ,in reality  I always had that problem with alpha blending.

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26 minutes ago, Wulfie Reanimator said:

except the rezzed hair is showing alpha problems 

Yes this is another problem that I haven't found a solution ,seeing through a model with alpha texture on it 

the faces missing aree those  layers who appear from the hair in the ground.

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  • 3 weeks later...

The problem your facing is called Alpha Z sorting, Essentially it's the draw order of the mesh itself causing the Alpha Z sorting problem, This occurs on both Rigged mesh, and un-rigged mesh. Though it tends to be more noticeable via Un-rigged mesh. Alpha masking Is the "Path of least resistance" way of fixing it, since it's rendered different. But ultimately I imagine it does not achieve your desired effect as Alpha masking tends to make the texture look less soft rather than hard. To fix the problem, you need to attach the mesh in an order, which the Render engine can understand, Also note that having Materials(Select faces) on the object can also effect the draw order. If your porting between programs this can also mess up the vertex order if the file format is wrong. 

Edited by Nergal Ninetails
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On 1/18/2020 at 3:23 PM, Nergal Ninetails said:

The problem your facing is called Alpha Z sorting, Essentially it's the draw order of the mesh itself causing the Alpha Z sorting problem,

Right. The key thing to realize is that, for alpha blending, depth sorting is for the entire face, not per pixel. If you have something with a complicated shape in near-contact with something else, like hair, head and clothing, it's ambiguous which face of which object is on top. For hair vs head, you can kind of make this work by making the hair partially transparent, with an alpha value around the middle of the range.

With alpha masking, depth sorting is per pixel, and the GPU does it. But alpha values are reduced to "on" and "off", using the threshold you set in the texture pane of the edit window. So the right stuff is on top, but the transition is abrupt.

To get a good sense of this, make a simple X of two intersecting flat surfaces, with a texture with an alpha channel on each. You can do this with prims.View this with all the combinations of alpha blending and alpha masking. That will let you see how these modes work.

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  • 3 weeks later...

 

On 1/26/2020 at 10:50 AM, animats said:

Right. The key thing to realize is that, for alpha blending, depth sorting is for the entire face, not per pixel. If you have something with a complicated shape in near-contact with something else, like hair, head and clothing, it's ambiguous which face of which object is on top. For hair vs head, you can kind of make this work by making the hair partially transparent, with an alpha value around the middle of the range.

With alpha masking, depth sorting is per pixel, and the GPU does it. But alpha values are reduced to "on" and "off", using the threshold you set in the texture pane of the edit window. So the right stuff is on top, but the transition is abrupt.

To get a good sense of this, make a simple X of two intersecting flat surfaces, with a texture with an alpha channel on each. You can do this with prims.View this with all the combinations of alpha blending and alpha masking. That will let you see how these modes work.

To my understanding if i'm understanding you correctly, You are saying the texture itself which has the alpha influences the zsorting of the alpha blending mode, or draw order of the mesh; In my experience I would say you're mistaken, the only two factors that i've seen that influence it are Material ids (Select faces) and how the object is attached together in the 3d program (Vertex draw order essentially)

On 2/4/2020 at 1:07 AM, ReinaLexigle said:

Hi,What is this order please ?

There's no number or order I can give you as it's different from object to object, my recommendation is to do research into Alpha Z sorting to understand how it works why it occurs and how to control it. That being said I'll give you some tool tips on what to look for. One influence is Material ID's (Select Faces) My memory is fuzzy but if you have multiple faces The overlapping object must be set to a higher material ID than the underlying object. The second influence is the (Draw Order), this is how you attach the mesh together. so hair for example you generally have Leafs of mesh, or Strips. You attach each object based on when you want it to draw. So (Underlying objects first) then the last ones should be The overlapping object.

The program I use is 3ds Max, so i'm not sure if it works the same in blender or Maya; but the guide is universal all around, and the bug isn't bias to one application.

Unfortunately it's very hard for me to explain what i mean in text but I hope this helps you out.

Edited by Nergal Ninetails
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1 hour ago, Nergal Ninetails said:

You are saying the texture itself which has the alpha influences the zsorting of the alpha blending mode, or draw order of the mesh;

It's a property of a face's texture settings. You can see those by editing the object, selecting an individual face, and looking at the "texture" tab. There's a dropdown menu with "None", "Alpha Blending", and "Alpha Masking" options. If you select "Alpha Blending", you get face sorting. If you select "Alpha masking", you get Z-buffered clipping on a per-pixel basis, which means alpha is on or off, not a fraction, but draw order doesn't matter.

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Ah, I see where the disconnect is happening, I'm aware of the 3 different alpha modes that second life has, what i'm referring to has more to do with what happens inside of the 3d program such as 3ds max or blender. While Alpha masking is great and less intensive on the render engine, the problem with it is your are incapable of getting see through effects, such as (Windows) with the mode, hence why Alpha blending is necessary for some objects. What i'm suggesting has entirely to do with the mode 'alpha blending' nothing else. 

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1 hour ago, Nergal Ninetails said:

the problem with it is your are incapable of getting see through effects, such as (Windows) with the mode

Which is why the golden rule in game content is typically "avoid alpha blending whenever you can get away with it".

Sometimes it involve adapting your content/vision to better fit the constraints of the platform, because the other way around is very unlikely to happen.

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21 hours ago, Kyrah Abattoir said:

Which is why the golden rule in game content is typically "avoid alpha blending whenever you can get away with it".

Sometimes it involve adapting your content/vision to better fit the constraints of the platform, because the other way around is very unlikely to happen.

 

Generally in my experience in game development you have a head artist, and you adapt to their vision, or they find someone who can.The second life platform is massively different than that of current engines. That being said I don't personally feel constrained by the Alpha blending mode aside from the fact that you cant control the draw order of other objects which makes comparability from different creators 'using alpha blending' impossible. But no offence to anyone I'm not looking to get into a debate about the topics, I simply wanted to provide some clarity to OG posters question, on how to fix their texture using the alpha blending mode; While I agree since it's hair they could probably get away with using Alpha masking, but honestly that wasn't the question.

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