C4DtoA 5 Image alpha transparency rendering as black

[Anonymous]

Hi,

I'm trying to create a shader that has a transparent area using an alpha mask (it's a label for a glass bottle). I've tried every solution I can find online and I can't get it to work, the transparent area always renders as solid black. I'm completely new to Arnold and trying to get my head around how the network editor works etc. Here's what it currently looks like... The area in black on the alpha file should show as transparent ie. the area below the yellow sash. Could someone help me with a step-by-step guide as to how to create it?

Many thanks in advance!

[Stephen.Blair · Accepted solution]

Add an Arnold Parameters tag to the geometry

Clear the Opaque check box

Connect the alpha mask to Geometry > Cutout Opacity (on a Standard Surface)

[Anonymous]

Brilliant, thank you. It's easy when you know how!

[Anonymous]

Help! It worked perfectly, and then as soon as I changed something and it rendered again it stopped working! The transparent area is rendering as black again. I've checked the 'opaque' option on the tag is unchecked. I've tried recreating the shader from scratch. Just can't get it to work again! Is there something I'm doing wrong? Are there any know glitches with C4DtoA that might cause this?

[peter.horvath6V6K3]

Seems like you have found a bug. When the Lathe object is under a Cloner, the Arnold tag thinks it's a spline instead of a polymesh, so in the end the shape has the opaque flag on. You can workaround this if you enable the Show custom parameters flag in the tag.

Try to fix this in one of the next releases.

[Anonymous]

Ok, great, the workaround worked! Thank you. Nice to know I'm not going crazy and there is actually a bug! I'm loving the results using Arnold.

[Alexandre_Perinelli]

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,

It seems that C4Dtoa is full of bugs nowadays ... is there any loosening into its development since it belongs to Autodesk ?

It would be difficult for me to enumerate all the small bugs I've noticed but I've faced as well to this one and it's definitely one of the worst ....very disappointing. 😞

[peter.horvath6V6K3]

I'm sorry if you feel there are too many bugs lately, maybe I became too lazy, but it's not because of Autodesk. 🙂

This specific problem with the Lathe object supposed to be fixed in 2.4.0. If you still have the issue, please send me a scene I can reproduce it with. Also would be nice if you could report all the bugs you have found (in a separate thread or to support). It's quite difficult to fix something I don't know of.