Author Topic: Alpha Channel on Glass and Mirror  (Read 6302 times)

2018-03-07, 16:43:40

nmkhaksar

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Hi all-
I was wandering if the problem of the alpha channel behind a glass material, or the alpha on the reflection and refraction channel on glass or mirror material is fixed. I am working with corona and Cinema4D, and I don't find this option. I was previously working with vray and we had the option of assigning an -all channel- tag in the reflection and refraction of a material.
Thank you for your time, Nima

2018-03-07, 17:37:18
Reply #1

beanzvision

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Hi all-
I was wandering if the problem of the alpha channel behind a glass material, or the alpha on the reflection and refraction channel on glass or mirror material is fixed. I am working with corona and Cinema4D, and I don't find this option. I was previously working with vray and we had the option of assigning an -all channel- tag in the reflection and refraction of a material.
Thank you for your time, Nima

Hey! Do you have an example at all of which you are referring to? I think I understand but not 100% :D

2018-03-07, 20:22:36
Reply #2

Eddoron

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I think I know what he means.

Turn off the object's visibility in the glass material. (visible in masks and in the composition tag of the object you want to hide)
The best way for that is to render the masks separately, by enabling the "render only masks(disable shading)" in the CRN render settings.

Left side with these options shown enabled/disabled.



2018-03-08, 11:17:41
Reply #3

nmkhaksar

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Thanks for ye answers.
Actually this is not about seeing the glass in the alpha channels.
I am referring to the fact of having the selection of a material behind the glass, with the deformation of the refraction, or having the selection of a material in the reflection (glass or mirror).
I have attached an example of an image I just did, I need to have the selection of the wood table in the reflection, and the deformed wood in the refraction of the glass/water.
I hope this is clear!

Thanks for your time


2018-03-09, 08:32:11
Reply #4

beanzvision

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Something like this?

2018-03-09, 08:59:30
Reply #5

nmkhaksar

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Beanzvision Yes!!

2018-03-09, 09:58:22
Reply #6

beanzvision

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Well, It's probably not the correct way to do it but my method was to split the table where the stripes were, hide the rest of the table from the render and turned on multipass/alpha. For the stripe material in the advanced option, I changed the Alpha mode to always white. And surprisingly it worked. ;)

Like I said, I know it's not the correct way to do it but in this case it works. :)
« Last Edit: 2018-03-09, 11:23:11 by beanzvision »

2019-04-23, 10:22:28
Reply #7

ARKlm

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I think I know what he means.

Turn off the object's visibility in the glass material. (visible in masks and in the composition tag of the object you want to hide)
The best way for that is to render the masks separately, by enabling the "render only masks(disable shading)" in the CRN render settings.

Left side with these options shown enabled/disabled.

In my last two render this method doesn't work....Before yes but now not...is this a bug?
Then I tried to put alpha mode (in advanced option) white or black, but nothing...I don't have any mask of the objects behind the glass. The only way is to turn off in the render the glass, but al the object's mask behind the glass are incorrect, because they ignore completely the refraction glass.
« Last Edit: 2019-04-23, 10:44:14 by 8snowman8 »

2019-04-27, 08:46:45
Reply #8

ARKlm

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Ehi Corona Staff, could you please give a feedback about my problem/question above?

2019-04-30, 16:09:35
Reply #9

maru

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I am not sure about C4D, but in Max this is currently not possible.
We know that this is an important feature, and we have it logged.
(internal: id=337617195)

2019-05-04, 08:48:21
Reply #10

ARKlm

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Thanks, maru. In archviz it is very important this feature (the glass mask and the mask of the objects behind), it will be perfect if corona could calculate one time both masks.
thanks
bye