(clicking) Great work! Now we've got all the math we
need for a computer program to draw as many lines as we need to create a good
approximation to a parabola. Let's return to some of the
artistic aspects of grass starting with the width. In this interactive, I
can move the points around and I haven't drawn the
legs of the control polygon just to make it look a little bit simpler and, let's see, that kind of shape for the
spine looks pretty good. So let me move on to the next step which is to define the width. I'm going to do that using
something we'll call a Skeleton. The Skeleton is a set
of lines, like these, that cut across the blade
of grass at 90 degree angles so here's a Skeleton line,
here's a Skeleton line and so on. If I connect all the left
sides of the Skeleton lines and the right side of the Skeleton lines, I create a region, let me fill that in, and that region looks a lot
more like a blade of grass. (click)
(tinkling) I can control the width
using this slider here so that's just adjusting the
length of those Skeleton lines and that width there looks pretty good. Finally, I can control the color. I can go from a deep green to a lighter green to a really light green. Our artists control parameters like this to create the kind of convincing grass that you see in "Brave." Use this interactive to see what kinds of blades of grass you can create and then, in the next video, we'll talk about how to animate it.