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### Course: Pixar in a Box > Unit 11

Lesson 1: Modeling grass with parabolas- Start here!
- Introduction to parabolic arcs
- 1. String art
- String art construction
- 2. Midpoint formula
- Midpoint formula
- 3. Parabolic arcs
- Parabolic curve matching
- 4. Modeling grass
- Design challenge: Modeling grass
- 5. Animating grass
- Design challenge: Animating grass
- Getting to know Tony DeRose
- Hands-on activity

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# Start here!

Overview of modeling grass with parabolas

# Welcome to environment modeling!

In this topic we're going to explore how realistic blades of grass are modeled using

**parabolic arcs**.This topic contains two lessons:

- Appropriate for grades five and up
- Design your own blade of grass using midpoints and simulate it as a flowing field.

- Appropriate for grades nine to 12
- Discover the equation used at Pixar to efficiently draw parabolic arcs.

## Have fun!

## Want to join the conversation?

- what is/are parabolic arcs?(60 votes)
- A parabolic arc is a section of a parabola. A parabola is a curve whose equation is in the form y = ax^2 + bx + c

You can learn more about parabolas here: https://www.khanacademy.org/math/algebra/quadratics(66 votes)

- Is it possible to code a parabolic arc like the one shown above using one or two for loops and a line?(19 votes)
- Yes, you can do with a single for loop. You can see a version here: https://www.khanacademy.org/pixar/parabolic-interpolation/5746702332723200

(Lines 110 - 116). You can change the RESOLUTION variable to make the line more or less smooth.(23 votes)

- Is this how people to animation? Its cool!(11 votes)
- Mathematics are used throughout the Pixar in a Box course, and computers have the capability to convert math equations into full-scale movies. ;)(13 votes)

- This page says that lesson 2 is appropriate for the high school level. Why is that? Is there anything I need to learn especially for that lesson?(15 votes)
- probably because there might be some math that you learn in 9th to 12th grade which you might need here(1 vote)

- What grade would be considered high school level for lesson 2?(8 votes)
- The first part of lesson 2 is appropriate for all ages, the second lesson is closer to a grade 9 level. Remember you can do these lessons in any order as well!(8 votes)

- What point are you guys making here in this article and besides it only tells of the blades of grass using parabolic arcs?(3 votes)
- Probably as in that scene the grass is waving in the wind, front and back, so they need to use parabolic arcs for the movement of the grass(2 votes)

- This is soooo awsome. I am gonna work at walt disney animation studios in a few years after high school and college and was wondering how many years of computer studies do you have to have?(3 votes)
- I think it depend on your knowledge and adoption of the knowledge.(3 votes)

- what are parabolic arcs(3 votes)
- I'm confused about this(3 votes)
- Why are parabolas important?(3 votes)