If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

5. Animating grass

Finally, let's bring our parabolic arc to life!

Want to join the conversation?

  • aqualine sapling style avatar for user Katie
    When animators draw, say, a field of grass, do they need to draw each blade individually (so they have different lengths, widths, etc.) or do they have a faster way to create the blades? Could they use object oriented programming (or something of the likes), with a random height and width for the grass?
    (11 votes)
    Default Khan Academy avatar avatar for user
    • leafers sapling style avatar for user Peter Collingridge
      Yes, you're right. They will have tool for generating whole fields of grass with slightly different angles, lengths, colours etc. There is an simple example in the next program, where you animate one blade of grass and it is replicated on a small grid of grass. In the real Pixar program it will be a lot more complex and create a more realistic effect. Also the movement of the grass is likely to be simulated rather than directly animated. It's quite very they use object oriented programming to store the different blades of grass.
      (18 votes)
  • male robot hal style avatar for user KEVIN
    Is the animation of the computer generated grass determined by the actual observation of real grass, or is there some imagination mixed in?
    (8 votes)
    Default Khan Academy avatar avatar for user
  • leaf green style avatar for user weber
    Are ubiquitous background items (clouds, grass, etc.) stored for future use--with stylistic variations--the way stock footage can be used in regular movies or videos?
    (6 votes)
    Default Khan Academy avatar avatar for user
    • male robot hal style avatar for user Matthias Schmitz
      I found a post from an anonymous person who claims to be a former pixar intern.
      You would think that a lot of assets are re-used, but the reality is that a lot of it has to be re-done. From a technical perspective, this is because the show's environment is usually very different. Specifically, the operations that shaders depend on change from show-to-show as new technologies emerge and old ones are deprecated.

      Models are often re-done (Toy Story 3 re-did the main characters) to update them to work with the current system. The build system that takes a model from its Maya file and converts it to a format readable by the proprietary system tries to take care of a lot of this, but even with the recent switch from the old animation system to the new one (starting with Brave), rigs needed to be re-created. In cases that an old asset is exactly what the new movie needs, TDs will try to tweak the old asset to work the with new show's build system.

      These technical reasons, coupled with the fact that the art direction of these films is very different. Assets in Cars were all themed to look like parts of Cars, assets in Monsters are themed to look like body parts of monsters.

      Long story short, the asset-centric part of the pipeline changes rapidly when new tech or new art direction comes along and as a result, asset re-use happens less than you might think at Pixar.
      (9 votes)
  • blobby green style avatar for user ronit5rg
    What are the softwares you use for creating the graphics and the animation?
    (6 votes)
    Default Khan Academy avatar avatar for user
  • aqualine ultimate style avatar for user Reigh The Riot
    I love animation. What software do I need?
    (5 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Pedro Vielman
      I agree with Jessica, Khan Academy is indeed a powerfull tool!
      But if you want to get a little more deep into animation you can use more advanced software devoted specifically for the task. Some examples are Stingray, Autodesk Maya (probably my favourite), 3DS Max and Blender. The cool thing is that many of this programs (including the ones listed above) can be downloaded for free and there are tons of tutorials on youtube if you want to get started. I encourage you to continue your research on these programs. Who knows you might end up creating some cool movies and games one of these days. Good Luck!

      Ohhhh and here are some videos for you to check out the power of these programs:
      (2 votes)
  • winston baby style avatar for user Aman Singh
    Which programming language are they using to make these software?
    (2 votes)
    Default Khan Academy avatar avatar for user
    • leafers ultimate style avatar for user Bryan Ray
      This educational application could be built in any language, really. Java would be a pretty good guess because it's easily portable, so you could put it on a computer in a school's computer lab and be reasonably sure that it would run easily.

      The software used to actually make the grass in production would have to be a fairly robust language such as C++.
      (3 votes)
  • orange juice squid orange style avatar for user vanessa
    how did the man in this video create a spare of grass? Just curious.
    (2 votes)
    Default Khan Academy avatar avatar for user
  • duskpin tree style avatar for user Paula Castiblanco
    At you say that you are going to create a different tutorial for randomness specifically. My question is, have you?, and if so, where can I find it? Thank you
    (3 votes)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user Montana Burr
    I'm just curious now, but do the animators use motion tweens?
    (2 votes)
    Default Khan Academy avatar avatar for user
  • starky seedling style avatar for user 1324354657
    How was the variation that we saw in the field of grass created?
    (2 votes)
    Default Khan Academy avatar avatar for user

Video transcript

- So far we've talked about how to create a blade of grass using a parabolic arc and a width parameter. We refer to this kind of geometry creation here at Pixar as Modeling. We've also talked about how to create a color, and we refer to that as Shading. Next we're going to talk about something even more exciting, that is Animation, how to make the blade of grass move. Notice in this shot how the grass is moving gently indicating a gentle breeze. We call this kind of subtle motion Keep Alive because if there was no motion at all it would appear stale or dead. But we don't want so much motion that it draws attention away from where the director wants you to be looking. So how are we going to animate each blade? Well to animate, I just need to know where each control point is in each frame of the animation. So, I can just record the motion as I move them around. So here's a simple little animation, and that's probably enough frames right there. And now I can replay that animation as many times as I like. In this case, I'm just cycling back and forth through the animation. So, this is how this one blade looks when animated, and here's how that motion looks when it's copied out to a bunch of blades of grass. Starts to give you a feeling for how a field of grass might move. But in this case, all the blades of grass are moving exactly the same which isn't very realistic, but we can add a little bit of variation by having each blade start the animation at a slightly different time, and that's what I can control with this slider here. So, I can add just a little bit of variation, or I can add a lot of variation. And now it's starting to look a lot more realistic. That's one way to add variation, but another way to add variation is using randomness. In fact, we use randomness so often and in so many different ways that we're going to devote an entire tutorial to it. But for now, use this interactive to see if you can animate two different shots. One with just a little bit of gentle Keep Alive like on a calm day, and another that looks like a very windy or stormy day.