Faces Transparency Issue

[Anonymous]

Hello, I've been having some trouble setting up transparency properly on certain objects in Maya, where seemingly random faces have different amounts or seemingly flipped faces when viewed through other transparent faces. I generally have two different methods for making objects like cups with transparency. One is by using splines and  revolving them to make the polygons, and it won't have this issue at all when I assign the material. However when building from box modeling or retopoing more unique objects, this issue occurs, especially if I use the insert edge loop tool. 

I've tested different shaders (currently using stingray as we use .glb for work) and messing with the normals in various ways but that hasn't helped either.  I've attatched an image from maya, and a 3d viewer, as well as the maya file for the model. I would really appreciate any help you can provide. Thank you!

[jordan.giboney]

Hi @Anonymous 

Thanks for being a part of our community and sharing your scene file! I will have a look at it today. 

For testing purposes, can you tell me what version of Maya you are working with (including update)? Select Help > About Maya to see what update you have installed. 

Also, can you tell me what render engine you are using to create these images? (Arnold, Maya hardware, etc.)

Thanks again for posting!

[Anonymous]

I'm using 2019.1. The images are just from the work view, with that "rendered" image from an online glb viewer. Although I've tested other viewers, file types, and materials but it occurs with translucency on all of the options. 

[jordan.giboney]

Hi @Anonymous 

Thanks for your quick reply! Thats very interesting. Would you be able to upload an example scene file to this thread so i can take a closer look at it?

Thank you for posting!

[Anonymous]

the glass.zip on my original post has a scene file with the problem in it. Thank you!

[mspeer · Accepted solution]

Hi!

Transparency is a problem for every 3D engine, but if your problem is the visible face pattern, then simply use

Edit Mesh -> Reorder Vertices

to get rid of this.

[Anonymous]

That worked! Thank you! Do you know why this happens? What does the ordering of these vertices have to do with the way it determines translucency? Also for future reference I found this video on the topic helpful as well. https://www.youtube.com/watch?v=j6hyEu1r48o&feature=youtu.be

edit: I did actually find a comment explaining why it does this:

"One specific case where ordering your vertices is important is realtime rendering of hair strands. The reason this is important is because the traditional alpha blended transparency does NOT order vertices which in turn produces weird results when you see alpha blended geometry on top of each other (image google "alpha blended artifacts" and see for yourself). The reason vertex order is important in the hair case is because we can take advantage of the fact that GPU renders vertices by their index order and make the interior strands vertices render first and render the exterior strands after and get less artifacts with it. This is just an example and even in this case there are limitations, for instance not all hair style interior and exterior hair strands so reordering the vertices wouldn't do anything to solve the issue."

[ankurroy8999]

help me. how to use reorder vertice to solve this issue