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I really like the design of Tyrael in the Diablo games and I LOVE the design and animation of his wings:

Not only in the great cutscene but also directly in Diablo II it was possible to admire them:

 Source: gamepedia.com
Left and right wings are not mirrored! Both wings are stored in single files each containing 60 frames for the animation. If you own the game you can use Dr. Tester to see the animation by yourself.

When Blizzard announced Diablo III I was very very very interested how they would realize those wings in a 3D engine. Let’s look at how it turned out:


Source: Diablo III

Wow…this looks amazing!

But how is it done? Sure, they could use an animated texture and map it to a plane but that would cost a lot texture memory. Using skinned geometry (like I did below as example) might be a possibility but would cost many bones.

However it’s made: there are several problems to solve:

  • The starting point of the wing must be fixed
  • You need a nice wavy movement
  • The wing should get thinner towards the tip

Source: Diablo III

I looked at their assets and to be honest at first I had no idea how they made such beautiful wings out of these “simple” textures:

Source: Diablo III

Important: I’m just assuming here and I don’t really know if my thoughts are correct!

OK, it’s easy to understand that you get a nice wavy movement by using a sine wave texture and moving it along a plane. BUT the starting point moves up and down and as I just mentioned: we need a fixed point:


Source: Diablo III

By looking at the in-game geometry I could see the trick: They deformed the plane so that the up-down-movement gets reduced on one side. Adding some subdivisions avoids that the texture stretches in a weird way like you can see on the left:


Source: Diablo III

This is good enough because the area where the wings connect is pretty big and allows at least a bit movement. This avoids that the wings look disconnected when the sine curve is at its minimum/maximum:


Source: Diablo III

By the way: The additional subdivisions let you add more deformation which can result in better and more interesting looking curve movement (faster/stretched at the beginning, slower/compressed at the end):


Source: Diablo III
Instead of deforming the geometry you could modify its UVs in the same matter but for better presenting what’s going on I decided to deform the plane directly.

Now we need to get rid of the opaque blue areas and here the texture’s alpha channel comes into play:

Source: Diablo III

Applying this gives us a nice animated wing “string”. It’s interesting to see that these plasma-like “fringes” seem to have a bit of life already:


Source: Diablo III

The only problem is that you can see the hard cut on the right side of the plane where the wave texture ends very abrupt (the left side isn’t a problem because there it connects to the angel’s armor which hides the harsh cut).

But this problem can be solved by using a second texture as mask (see below). Another idea is to use vertex color as transparency mask but of course a texture mask gives more control with details.

Source: Diablo III

To the right you can see how the applied mask improves the wing experience. Very interesting: the transparency in addition with the slightly squashed geometry makes the end of the wing look thinner which was one of the three mentioned problem zones!


Source: Diablo III

Now we can duplicate the plane several times to make the wings look like in the Diablo game. And to get some variation we can offset the UVs of the planes a bit:


Source: Diablo III

But as you can see this produces several problems. We’ll talk about some solutions below:


Source: Diablo III

One problem is that the texture tiles/wraps and therefore “starts again” when the UV shell is reaching over the 0-1 border.

Source: Diablo III

This can be solved by setting the texture tiling mode to : Clamp.


Source: Diablo III

Clamping basically means that the border values of the texture are repeated forever instead of the whole texture (like it happens when you tile/wrap it):

Source: Diablo III

To avoid the last problem with the harsh cut at the right side (see above) you can stretch your UVs so that it aligns with the mask again:


Source: Diablo III

Another solution I really like is using one UV set for the wave texture and another one just for the mask (without any offsets in the UV shells). I don’t know if they did this in the game because I couldn’t find such a 2nd UV set in the assets.

Source: Diablo III

By using a 2nd UV set you don’t get any problem which we talked about above but clamping the mask texture might come in handy anyway even if the UV shells don’t overlap the 0-1-area some pixel bleeding might happen:


Source: Diablo III

However you solved the problems, if you now don’t use boring planes like in my examples but pimp it up a bit then you end up with a beautiful geometry like this which is used in the game:


Source: Diablo III

The curved surfaces add volume and even if it looks a bit complicated you should remember that it’s “just” made of subdivided and deformed planes:


Source: Diablo III

As you can see there are some planes without subdivisions which actually do suffer from some “weird” texture stretching (like explained at the beginning of the article) but this gets very well hidden by all that other movement going on.
And these planes seem to use a different texture for the masking (I named it “Mask 2”). But I might be wrong here.

If you’re interested in seeing the UVs, here you go:

Source: Diablo III

If we apply our material to this wonderful geometry (and push the intensity a bit) it looks really similar to what you can see in-game:


Source: Diablo III

Do you remember the “Pattern” texture (mentioned at the beginning of the article)?

Source: Diablo III

I wasn’t sure how it’s used in the material but luos_83 suggested it could be multiplied with the mask texture which looks very reasonable:


Source: Diablo III

This adds a nice additional detail to the whole effect:


Source: Diablo III

Here’s my final material. But as I said: It’s only an assumption!

Again I’m totally in love with how Blizzards artist combine several “simple” steps to create something stunning. Only one thing I don’t like that much: When the characters move, the wings follow immediatelly without secondary motion:


Source: Diablo III

Not a major issue but got handled later – in a different BLizzard game: Heroes of the Storm improved the wings in that regard:

You can admire the dynamic wings in the menu as well as directly in the game:

The textures look similar to what was used in Diablo III but in addition to the wave texture they actually transform the geometry!

Here you can see the wings in the main menu:

And here you can see how the geometry gets transformed:

In my eyes these wings are a great example how game development works: We constantly have to overcome problems which look intimidating at first but can be beaten by using several small and creative solutions.

Thanks for reading and I hope you like what saw. Have a nice day! :)

Update 1

How awesome is that? Jill Harrington, the creator of the wings for Diablo III, said hello and revealed some more details for us:

Bloom Amount

“The second, darker mask texture is to modulate the bloom amount. Without it, the wings were still too bright at the tips. It also tints the bloom a bit.”

Fill Planes

“Those little planes that aren’t subdivided are just there to fill in the wing base a bit without adding too many polys. The not-so-great texture artifacts don’t show in the whole wing, I think!”

Secondary Motion

“There actually is a small amount of secondary motion in the wings on NPC angels. They have a rig with a handful of joints controlled by limited ragdoll. When they were created, we couldn’t set a gravity that wasn’t either “up” or “down”, so stronger physics would have basically made droopy broken wings and killed the illusion.”

Overdraw

Of course the amount of overdraw with all those layered planes with soft alpha makes me wince, but they never caused a performance hit so they got to stay that way!

Thanks a lot Jill for sharing all those information with us! :)

31 thoughts on “Diablo 3 – Wings of Angels

  1. Matthias

    Wow, nice breakdown. Another very well explained technique on your Blog. Keep it up, it’s awesome and very helpful for people like me who are getting into FX stuff :)

    Reply
    1. SimonSimon Post author

      Thank you! Yeah I’ve noticed that it’s easy to find tutorials for “normal” game art but VFX is still an issue when it comes to tutorials…or do you know good resources for that?

      Reply
      1. Nico

        I feel the same way. There are few good resources for VFX out there. So much easier to learn amazing environment art techniques because of all the stuff that is out there to learn from. VFX is like: “There are a million amazing techniques used in the latest games, but nobody ever explains them to you. So go figure them out by yourself!” :D I’m happy I found a site where you try to break down a VFX technique once in a while.

        Reply
      2. Matthias

        I found some Tutorials on Youtube from different people. I’m working with UE4 so I looked for UDK and UE4 tuts.
        I got some from people I don’t know where there working, for example this guys:

        https://www.youtube.com/channel/UCA-sP_G8gDY0V9YOOpK7V1g
        https://www.youtube.com/watch?v=G9vKSqRzhGQ

        Of course, Epic’s introducing to Cascade and particles is a good start

        https://www.youtube.com/playlist?list=PLZlv_N0_O1gYDLyB3LVfjYIcbBe8NqR8t

        But there’re also some twitch streams which were done by the Epic Games customer relation department, so some Senior VFX artist show their techniques (didn’t watch all of them by now)…one is missing, can’t find it. Hopefully I can dig this out my browsing history.

        http://www.twitch.tv/unrealengine/v/16480921
        http://www.twitch.tv/unrealengine/v/13926101
        http://www.twitch.tv/unrealengine/v/12749804
        https://www.youtube.com/watch?v=dtuLOxSkciA

        And i found this Blog also:

        http://valdism.blogspot.de/2014/04/vfx-tips-making-smoke-textures.html

        Reply
        1. SimonSimon Post author

          Wow that’s a very cool list! I already knew the Unreal Introduction which is really great but the others are awesome too! Thanks for sharing! :)

          Reply
  2. mariospants

    Just discovered your tutorials, this is wicked stuff, and you dissect it in such depth and provide those short video snippets so that nothing is missing… like I said, really great stuff, I’ll retweet it for sure.

    Reply
  3. Strelock

    Thanks for such great content, Simon. So glad that i found this blog :)

    Can you tell me the name of the tool you used to show Tyrael’s wings geometry and textures in game, please? Or is this done by modifying game assets?

    Reply
      1. Dubious

        I would like to know also. Is there some general application that works for most games or did you use some Blizzard/Diablo-specific software?

        Reply
        1. SimonSimon Post author

          Sometimes you can find modding tools but sometimes it’s better to use tools like for example Intel GPA.

          Reply
  4. essimoon

    Really great insight. I always wondered how Tyraels wings work in HotS :D
    Do you think the secondary motion is done with bones? or inside the shader?

    Reply
      1. Flo

        Was wondering about the same thing, the rest is pretty much straight forward but i could have used something like this secondary motion in the past. I would die to know if there’s a reasonable shader based approach.
        And again a really nice breakdown btw. So props to you simon!

        Reply
        1. SimonSimon Post author

          I could imagine that you can apply a sine curve into a vertex shader but that the shader reacts to the players movement…no idea. We should ask a shader-pro. Or someone could apply for a job at Blizzard, crawl through their documentation and tell us :D

          Reply
      2. HellGate

        first: your articles are great keep it up!

        to the dicussion: my guess is that they are simple ribbon emitters with initial velocity or maybe not an emitter but using verlet constraints to keep the ribbon geometry in place. since there is not uv maped mesh this would be much easier than transforming bones (like jiggle bones in the source engine)

        PS: also interested in what you used to get the wings geometry. i know how to get the textures but only them
        PPS: can you make middle mouse clicks on links work? ;)

        Reply
        1. SimonSimon Post author

          I’ll write you a mail regarding the programs but what problem do you have with the middle mouse button? When I click a link it opens in a new tab (Chrome Browser). How does your browser behave?

          Reply
  5. HellGate

    thanks a lot.

    the middle mouse problem seems to only affect the comment section (opens new tab but the original one loads the page as well)

    Reply
  6. Tororin

    Thank you for this article. You’ve must have spend a ton of time to discover and compile all of this know-how.

    Reply
    1. SimonSimon Post author

      It tooks some time yes, but only a fragment of what I’ve spent for example into the Render Hell article. :) So it’s fine and with all this nice feedback it was totally worth it. :)

      Reply
  7. Poobox

    Hey Simon,

    A lot of the effect is explained in this GDC talk, in fact it’s a truly brilliant insight into the VFX of Diablo.

    For example areas of interest for me are the BlendAdd method and the tex1 * tex2 * 2 which are used extensively in all their effects to not only make then stand out but also to create effects which look far more sophisticated than they actually are.

    Link to talk here: (I could type for hours, but obviously this guy nails it)
    http://www.gdcvault.com/play/1017660/Technical-Artist-Bootcamp-The-VFX

    Reply
  8. Gavin Gao

    omg,it is a amazing video that is so clear ! it is my pleasure to meet u simon!,
    iam a newbee in 3d game vfx ,but i am into it so much!
    would u give me some web address that u think is good for me to learn those stuff?
    and blizzard game’s texture where can i get?just give me some clue!
    sorry about my english and so much ask ^^

    Reply
    1. SimonSimon Post author

      great to hear that you like my videos :) i hope you’ll like future ones too :) regarding your questions:

      i’m sure you already know that google/youtube is full of awesome tutorials. i think the next step is to have a good community. i’m mostly visiting polycount.com where you can find tons of awesome people which can help when you’ve questions. also you should checkout the polycount WIKI which is a goldmine containing tipps and tutorials – you could spend days reading through it. :D

      but the most important 1st step is to have a goal. when i started with 3D i didn’t have a goal and therefore didn’t make progress. so it’s good if you set yourself a goal like for example making a hat for team fortress 2, a skin for dota 2, some small mod or create an artwork of your favorite character/environment. but maybe i underestimated you and you already know what you want to make – which would be awesome!

      regarding the textures from blizzard there’re ways to get them but wouldn’t it be way more useful if you try to create them by your own? i mean, that would be a wonderful goal, wouldn’t it? :)

      Reply
    1. SimonSimon Post author

      I’m very certain it is. Why not give it a try? ;) And make sure to share your results with us! :)

      Reply
      1. okami

        Hi,
        I started to make test in CryEngine 3 but I have some issue because the countours of the plane are visible, my mask doesn’t seem to work.
        I have only 1 material with 1 UV set.I don’t find the option in CryEngine to make the mask texture clamp (extent option in Blender).
        I used a decal option to make the mask (opacity texture) in CryEngine but I am not sure it’s the right way to do this.Also I had to make the option to increase emittance but that maybe the reason why it’s too bright.
        https://media.giphy.com/media/IGBQm3tBR4I48/giphy.gif

        Reply

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