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Complex material help

bearrrs
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bearrrs polycounter lvl 3
So I really suck at materials. It's the thing I think I'm weakest at. I understand how to set up your basic material and the fundamentals of PBR, but when it comes to anything more complex I'm pretty lost.

I'm sure getting better at materials is something everyone could benefit from, so if anyone has any really great material tutorials they'd like to share I'd really appreciate it.

Thanks!
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  • Vailias
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    Vailias polycounter lvl 18
    I'm in process of building a video series on this topic currently. :)

    But I suppose a good question to start with for right now is "What do you want to achieve?" Is there a specific material you're wanting to build right now but don't know how?
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  • bearrrs
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    bearrrs polycounter lvl 3
    Awesome, I'd obviously be super interested in that, so let me know when you finish if you can!

    I'm in a game art program right now at college, and this semester alone I've made 3 unique environments completely different from each other. so there have been a lot of various materials I've made that I'd like to improve.

    To get more specific, the most recent I've been having trouble with is creating a really good crystal material. Additionally, I've had a few friends try to tackle a lava shader, and come out with OK but not great results.
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  • Vailias
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    Vailias polycounter lvl 18
    Ah well I hope your game art program is way better than my game programming program. :)

    That said, what you need most when dealing with materials is good sold maths skills. Specifically geometry, algebra, linear algebra, and some very light calculus doesn't hurt. Its not as scary as it sounds though. ;)

    What you need just as much, is good solid observational skills. Being able to dissect the look of a surface into its component contributions is really key. Its what you need the math for. Just knowing the math is the tool to make observation into reality.

    So for your crystal material, you're thinking of something like a diamond, or gemstone I imagine like the attached, yes?

    I'll assume you know the basics of material creation so I'm not going to go too in depth on that, but I'll give a few pointers to what distinguishes translucent materials like this.

    For this kinda material there are 3 distinct parts. Reflection, refraction, and transmission.

    Reflection is handled in UE4 mainly via roughness and or specular.
    Transmission is essentially the same as opacity, so you wont want it to be completely clear.
    Refraction is an unitless index. In UE4 materials, this is a float that corresponds to the materials refractive index. Here's a handy list http://hyperphysics.phy-astr.gsu.edu/hbase/tables/indrf.html


    Another important piece to know, and notice, is that reflection and refraction happen only at surface boundaries, not within a volume, also, note that 3d objects surfaces are single sided, while a translucent material in the real world has at least two visible boundaries between the material and air, so there are two points of transition. Two solutions you can try, 1 is to make the material double sided, the other is to actually make the crystals double sided, with a slight offset so they're sort of hollow crystal shapes.
    This inward face creates a second set of shiny reflections and a second refraction of the scene behind, both of which are fairly crucial to selling a shiny translucent material.

    I have to stop writing now, but that should be some decent research material for you, and hopefully point you in the right direction.

    Also if you want, subscribe to my youtube channel: https://www.youtube.com/user/vailias I have some tutorials there already, some showoff stuff, and will be putting the upcoming videos there also.
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  • bearrrs
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    bearrrs polycounter lvl 3
    It's a really great program for the most part, I think, but it's a little broad, so if you want to get really specific with things like particles or materials you sort of have to seek that out yourself.

    Also, I hadn't considered your solutions for handling the two points of transition at all. I'll definitely try that out.

    Thanks for the advice, it was really helpful and I really appreciate it. I subbed to your channel on youtube. : 3
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  • makinmagic3
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    makinmagic3 polycounter lvl 11
    A good tutorial I think is "Complete introduction to materials in UDK", while it's not UE4 or whatever engine your using, it still gives some tips about material nodes and how they combine together.

    Just wait for the price to go down (on offer or something) - website usually has deals on every now and again.

    Link: https://www.udemy.com/3dmotive-the-complete-introduction-to-materials-in-udk/#/

    Also check out the UE4 content example project, and see how the materials are setup there.
    or check out the Unreal Engine youtube channel.
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