Datasheet

The Ring class has a respawn() function which computes a new particle's intensity and hue

based on the speed and angle of mouse motion. As parameters, it takes the X and Y

coordinates for a previous and a new mouse position.

class Ring

{

float x, y, size, intensity, hue;

void respawn(float x1, float y1, float x2, float y2)

{

// Start at the newer mouse position

x = x2;

y = y2;

// Intensity is just the distance between mouse points

intensity = dist(x1, y1, x2, y2);

// Hue is the angle of mouse movement, scaled from -PI..PI to 0..100

hue = map(atan2(y2 - y1, x2 - x1), -PI, PI, 0, 100);

// Default size is based on the screen size

size = height * 0.1;

}

void draw()

{

// Particles fade each frame

intensity *= 0.95;

// They grow at a rate based on their intensity

size += height * intensity * 0.01;

// If the particle is still alive, draw it

if (intensity >= 1) {

blendMode(ADD);

tint(hue, 50, intensity);

image(texture, x - size/2, y - size/2, size, size);

}

};

Now we need to define the rest of the program to drive a system of these Ring particles.

Aside from the Ring class, this is what the rest of our program looks like:

OPC opc;

PImage texture;

Ring rings[];

float smoothX, smoothY;

boolean f = false;

void setup()