Forked from: https://gist.github.com/gtb104/3667340
Here's a d3 plugin that allows you to create a polygon selection. You instantiate it just like d3.svg.brush.
var brush = d3.svg.polybrush();It has an extra public method that 'brush' does not, and that's 'isWithinExtent(x, y)'. You can use this method to test if a given point falls within the drawn extent.
if (brush.isWithinExtent(x, y)) {
console.log("I'm inside!");
Forked from Tom MacWright and updated by Christopher Manning
This adds simplex noise to the waves. The 3D noise uses the parameters x and y. z is a function of the velocity and frame from d3.timer.
By adding transitions, we can more easily follow the elements as they are entered, updated and exited. Separate transitions are defined for each of the three states.
Note that no transition is applied to the merged enter + update selection; this is because it would supersede the transition already scheduled on entering and updating elements. It's possible to schedule concurrent elements by using transition.transition or by setting transition.id, but it's simpler here to only transition the x-position on update; for entering elements, the x-position is assigned statically.
Want to read more? Try these tutorials: