Hi Guys;
As you can see in my attached file, I applied a transparency texture to my geometry.
My problems are :
1) The transparent area doesn't render correctly.
2) The transparency doesn't affect Alpha !

Any idea to solve these problems..?

Thanks.

Any Idea….?

I'm not up to speed with Mantra, but from other software solutions it might be a differentiation between transparency and clip map or its equivilent… ie. mask.

When I tried Arnold (sitoa) I discovered that it doesn't output the alpha from transparency (obeying IoR values) - not in a straight forward manner anyway, maybe there's some shader wizardry to circumvent that limitation of the Standard uber shader - I hope Mantra shader isn't crippled in the same way.

Hi, I'm using a daily build (542) which seems to have removed a lot of shaders from the SHOP gallery, which is where I'm used to working. I had a look in MAT and found the Classic Shader which is the equivalent of the Mantra Surface Shader (SHOP). Using a black/white texture in the opacity tab on this Shader works as expected. (giving the results you need)
Trying the same method with the Principled Shader doesn't seem to work. ie. Set Transparency to 1, got to surface textures tab and add black/white texture to Transparency.

To be honest, I'm so accustomed to the SHOP that I'm finding the transition to MAT a bit frustrating. The old Principled Shader in SHOP could be edited to allow transparency maps. The new one in MAT seems to have something setup already but I can't get it to work and haven't looked inside yet.

Rob

It is as the posts above said: The reason why you're getting solid alpha is because transparency and opacity are not equivalent.

Transparency is basically refraction, so its affected by ior, roughness, and lighting (this is why you're seeing the environment map in the parts that are transparent, unless you turn off its visibility in refraction).
Opacity treats as if the parts of the object is not there, so it does affect alpha.

The principled shader doesn't have opacity map built-in, but there are a number of ways to get the effect you're looking for (eg using layer mix).

robsdesign: can you elaborate on the issue you're having with transparency maps with the new principled shader?

Right, opacity is more of a screen door effect… you think you can see through something but only because the individual holes / negative space are too small to discern.

Most usable renderers make a distinction.

Dlee, I'm just comparing the old Principled Shader to the new one, or rather MAT vs SHOP. The old one had no opacity but by following instructions from the forum, I managed to dive in and add it myself. https://www.sidefx.com/forum/topic/43020/?page=1#post-194315 [sidefx.com]

As you can see on that thread, I'm using a metal/roughness workflow and had issues with the Mantra Surface shader's metallic setup. Adding an opacity map to the principled was a workaround.

It may be because I do 99% of texturing in Substance Painter so I just need a simple/efficient way of applying those maps. For something like an alpha/opacity map, it just seems a bit messy to have nodes plugged in to the shader rather than to use the UI generated by the shader's contents.

I don't want to elaborate too much as I've not had enough time to explore either the new MAT workflow or dive into the Principled shader. I will have to test Substance metal/roughness workflow with the Classic and Principled shaders again.

I'm sure there is some key points that I'm not aware of so I'm hoping for some tutorials/quickstart on the MAT workflow.

Rob

Thank guys for reply:
I solved the problem by connecting the “Principled Shader” node and a “Texture” node to a “Compute Lighting”. The Texture node is where I put my transparency image in.