Hair Sampler Transparency not seem to work

[dpotuznik]

Hi,

Sorry for all my questions i am new on Houdini and i have V-Ray for a few month and we start a big project (i am a little stressed). So i don't know if it's a bug or i just don't know how to do that

i try to get the alpha from my line, i get the color but the alpha not seem to work.

Thank you for your help.
Best Regards
Daniel

[dpotuznik]

Hi,

If i try to use the userFloat it crash houdini.

Thank you for your help.
Best Regards
Daniel

[thomaskc]

No it's a bug I'm pretty sure, its easy to test if you create a grid with and apply material with a transparent png and use it for say diffuse and transparency, on cpu it works like you would expect, but on GPU it looks veeery odd hehe

[dpotuznik]

Thank you for your feedback,

But i use the CPU, and even then it not working.

i found a workaround to create a polywire so it create a real polygon, but i see the air shader render that more quickly and need less memory.

[dpotuznik]

mmmhhhhh but, not really a workaround , he take more than 3 min by frame to generate the wire ..
so i really hope to found a solution for this.

i found another workaround it's to use the color and map the color to the alpha and use a black and white and recolor the ramp for the color.

[chakarov]

Hello dpotuznik , are you trying to put @Cd as a color for the material and @ Alpha as transparency? If yes, than you could just use VRay UserColor and VRay UserFloat to get the attributes.

edit:
but for some reason everytime render is pressed the @ Alpha is different, I've added the issue and will message here once it is fixed.

[dpotuznik]

Hi,

Thank you for your response,
yes i tried that y have set on my geometry @Cd and alpha but houdini crashes when i render.
If you look on the video , maybe i am doing someting wrong ?

Thank you for your help.

[chakarov]

Yes, it happens once on my side, but couldn't get the reason of it. Anyway, I've logged it.

[dpotuznik]

Hi,

Thank's, in the meantime i have an workaouround, i use the color to map the alpha and recolor the black and white ramp

Have nice day,
Daniel

[chakarov]

Hi again dpotuznik , it looks like this issue is fixed in nightly build from today. I'm not getting any crashes or inconsistent @ Alpha attribute. Renders fine with HairSampler and with UserColor, V-Ray Material and V-Ray Hair material. You do not need colorToFloat or floatToColor or any kind of value converters, they are there only for internal use, all the attributes types are automatically converted during render.

[dpotuznik]

hi, Perfect thank you very much .. this is why i love v-ray
you rock.
Best regards
Daniel

[dpotuznik]

Hi @chakarov,
Sorry i am pretty new on v-ray, i have an link for the nightly , but i don't sure is the right one, i don't see the folder for houdini anymore.
Thank you for your help.
Best Regards
Daniel

[chakarov]

Hello dpotuznik , once you've purchase the license you should get access to stable nightly builds. If you have some problems with access to them you should write to support@chaosgroup.com.

[dpotuznik]

ah ok , yes i was in trial .. i bought now
Have nice day.
Best regards
Daniel

[dpotuznik]

but i don't see houdini on https://nightlies.chaosgroup.com/main , i see all the other but houdini disapears from the list yesterday.
(i already have a annual liscence for modo also )