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Ceciliabr
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A major challenge?

Question:
Is it very difficult to include alpha channels for sky or ground ( or both) as an option?
According to this paper alpha channels are already supported in Sunflow. I'm not into coding and hold no expertise in the field, so I'm just wondering if it's a major challenge.

cec
[Sep 13, 2016 5:01:51 AM] Show Printable Version of Post    View Member Profile    Send Private Message    http://cecprojects.wordpress.com [Link] Report threatening or abusive post: please login first  Go to top 
mazoola
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Re: A major challenge?

I've used images with an alpha channel as textures, with varying degrees of success. (For instance, in my never-ending quest to find a functional 'frosted glass' material, I came up with this:

That uses a black-to-grey diffusion cloud image with a different black-to-white diffusion cloud as the alpha channel. While it's an interesting effect, I can't say it's an entirely successful one: For one thing, in the scene there's a nude woman[1] standing immediately beyond where you see that square grey shadow; for another, that square grey shadow is somehow being cast by the cube in the left foreground -- through the wall, with light from a nonexistent source.) So, as long as you don't mind the resulting image thoroughly violates the laws of physics of the virtual universe where the scene resides, I guess you could say alpha channels work.

Actually, I probably could have lived with a chaotic upheaval of the basic rules of existence had I only been able to get them to fail dependably. Instead, the outcome of the render was incredibly variable, based on a range of factors I could never identify. For instance, when I took the texture used in the previous example and applied it to individual bricks in this 8 x 4 glass brick bathroom wall[2], this was the result:[3]

Ultimately, I threw in the towel and tried to find another way to fake it.

Maz
__________
1. After all, this was a test for a frosted glass shower stall.
2. Similar to the one in the house where I grew up.
3. The other very obvious bug -- namely, the 'melting' marble splash panel -- was the result of my having erroneously both softened and smoothed edges in the original SketchUp model.
[Sep 14, 2016 4:13:47 AM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
okh
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Re: A major challenge?

Ah, yes those pesky frosted windows. Glad to hear I am not the only one who has struggled with those. What looks fine in the 3D window, somehow turns out quite differently when rendering. And also, if to semi transparent surfaces overlap (one behind another), they are sometimes displayed in the wrong order. But with some trial and error, I usually get it right (for my limited purposes, anyway).

However, I suspect what Cec would want, is to apply transparency to ground and sky - to remove all or parts of the surroundings of a construction. I can see that for her designs (and sometimes even mine) it could be useful to remove background completely - but maybe I misunderstand.

ok
[Sep 14, 2016 8:27:39 AM] Show Printable Version of Post    View Member Profile    Send Private Message    Hidden to Guest [Link] Report threatening or abusive post: please login first  Go to top 
Ceciliabr
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Re: A major challenge?

@mazoola

Hm.. I never had any trouble with frosted glass... I think.




There'a a reason God let there be light.





Without proper lighting, her mammalian protuberances are (unintentionally ?) quite visible :




It's like thin, semi-transparent curtains: they prevent us from being seen during the day, but when the night falls, they offer no protection at all - unless we light them from the outside.


cec
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Miker777
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Re: A major challenge?

tut tut cec
wouldn't catch me doing something like that wink
[Sep 14, 2016 9:49:12 PM] Show Printable Version of Post    View Member Profile    Send Private Message    Hidden to Guest [Link] Report threatening or abusive post: please login first  Go to top 
Ceciliabr
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Re: A major challenge?

@okh

No, you did not misunderstand me. It's only the sky and the ground that do not utilise transparent textures.

The reason I'm mentioning this yet again ( yes, I have posted a question about this earlier), is because I have come across other threads wishing for the same. Most other 3D applications offers both alpha channels and shadow-catchers, and people designing homes, might like to place renderings of their homes on snapshots of the location it's meant for – a pre-visualisation of their future home.

I'm just wondering if implementing alpha channels for sky and ground are very difficult tasks to perform.

cec
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Ceciliabr
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Re: A major challenge?

wink @Miker777

Like what? Like showering in high heeled shoes? wink
[Sep 14, 2016 10:00:44 PM] Show Printable Version of Post    View Member Profile    Send Private Message    http://cecprojects.wordpress.com [Link] Report threatening or abusive post: please login first  Go to top 
okh
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Re: A major challenge?

..you did not misunderstand me...
Glad we see eye-to-eye.

What also would be nice, is to have the (general) transparency slider bar available in the material dialogue (as it briefly appeared in a 4.2 beta, see thread 4444).

Just my fifty American dollars worth...

PS Mammalian disturbances aside, I suppose rooms/walls do not support transparency either - but probably also not necessary?
[Sep 15, 2016 7:58:23 AM] Show Printable Version of Post    View Member Profile    Send Private Message    Hidden to Guest [Link] Report threatening or abusive post: please login first  Go to top 
Ceciliabr
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Re: A major challenge?

@okh

I forgot walls and rooms, probably because, as you suggest, it's unnecessary.
A transparency slider bar would be great. I'm using Photoshop to manage transparency values of textures, but, as my illustration shows, the effect of semi-transparency depends a lot upon how the lights are placed.

cec
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okh
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Re: A major challenge?

Cec, you are absolutely right, and prove it often, that it is possible to work miracles with lights (and transparency) in terms of rendering. Alas, my favourite computer is pretty slow (but tiny, fanless and absolutely silent) and I am not very patient. Still, I manage to create renderings that are good enough for my purposes. But what I have tried to do, but have yet to manage, was making a lampshade that would let through a soft glow coloured by the lamp shade (and normal light under). After having tried different combinations of
- transparency in the .mtl file,
- transparent, combined and semi-transparent .png/.gif textures,
- and a few other things,
the result always came out - well - underwhelming.

For a short period during the 4.2 beta-testing the colour dialogue looked like this.
This, would be nice to see operational (was there something with Java in Linux?).

Ah yes, and I just spotted Miker777's comment.
tut tut cec wouldn't catch me doing something like that
That's fine, I can live with that smile

The most pleasant surprise with this whole discussion, though, is the fact that this thread is now appears to be in breach of Facebook community standards. Whatever else comes out of it, that counts for something...

ok
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