Manipulating force

So far, we have explored many interesting aspects and applications of D3 force; however, in all of these prior recipes, we simply applied force layout's computation (gravity, charge, friction, collision, and velocity) directly to our visualization. In this recipe, we will go one step further to implement custom force manipulation, hence creating our own type of force.

In this recipe, we will first generate five sets of colored particles then assign corresponding colors and categorical force pull to user's touch, hence pulling only the particles that match the color. Since this recipe is a bit complex, I will give an example here: if I touch the visualization with my first finger, it will generate a blue circle and pull all blue particles to that circle, whereas my second touch will generate an orange circle and will only pull the orange particles. This type of force manipulation is commonly referred to as categorical multi-foci.

Getting ready

Open your local copy of the following...