This sketch has been adapted from a sketch done by Adrian Park. If you have a multitouch screen then you can make sparks appear at any point of contact, otherwise sparks will appear around the mouse pointer.
[processing] // Multitouch Sparks // Adrian Park// Multitouch Sparks
// Adrian Park <http://www.adrianpark.com>
// 2012
ArrayList mouseTrail;
int prevMouseX;
int prevMouseY;
// if multitouch events are fired, this is set to true
boolean useMultiTouch = false;
void setup() {
size( 655 , 630 );
background( 0 );
smooth();
mouseTrail = new ArrayList();
}
void draw() {
background( 0 );
if( !useMultiTouch ) {
// respond to mouse movement
if( mouseX != prevMouseX || mouseY != prevMouseY ) {
// create a spark if the mouse is moving
Disc newDisc = new Disc( mouseX, mouseY );
mouseTrail.add( newDisc );
}
prevMouseX = mouseX;
prevMouseY = mouseY;
}
updateDiscs();
}
// instructs each spark to draw itself and removes extinguished sparks
void updateDiscs() {
for( int i = mouseTrail.size() - 1; i > 0; i-- ) {
Disc d = (Disc) mouseTrail.get(i);
if( !d.isAlive ) {
mouseTrail.remove(i);
}
d.render();
}
}
// respond to multitouch events
// COMMENT THIS OUT TO MAKE APP COMPILE IN PROCESSING IDE
//*/
void touchMove(TouchEvent touchEvent) {
useMultiTouch = true;
for (int i = 0; i < touchEvent.touches.length; i++) {
int x = touchEvent.touches[i].offsetX;
int y = touchEvent.touches[i].offsetY;
Disc newDisc = new Disc( x, y );
mouseTrail.add( newDisc );
}
}
//*/
// Multitouch Sparks
// Adrian Park <http://www.adrianpark.com>
// 2012
class Disc{
int discRadius;
int minRadius = 2;
int maxRadius = 10;
float discAlpha = 255.0;
float alphaIncrement = 5;
float xPos;
float yPos;
float xVel;
float yVel;
float friction = 0.98;
float gravity = 0.1;
int maxStartingVelocity = 8;
// colour library
color[] colours = new color[3];
color c1 = color(255, 204, 204);
color c2 = color(255, 255, 204);
color c3 = color(204, 255, 204);
color c4 = color(204, 255, 255);
color c5 = color(204, 204, 255);
color c6 = color(255, 204, 255);
int renderColourIndex;
color renderColour;
// false when alpha <= 0
boolean isAlive = true;
Disc( int x, int y ) {
discRadius = round( random( minRadius, maxRadius ) );
PVector vector = getRandomVector();
xVel = vector.x;
yVel = vector.y;
xPos = x;
yPos = y;
colours[0] = c1;
colours[1] = c2;
colours[2] = c3;
colours[2] = c4;
colours[2] = c5;
colours[2] = c6;
renderColourIndex = round( random(0, colours.length-1 ) );
}
// draw the spark to screen
void render() {
if( isAlive ) {
renderColour = getColour();
fill( renderColour );
noStroke();
ellipse( xPos, yPos, discRadius*2, discRadius*2 );
// update properties
discAlpha -= alphaIncrement;
xPos += xVel;
yPos += yVel;
xVel = xVel * friction;
yVel = (yVel * friction) + gravity;
if( discAlpha <= 0 ) {
isAlive = false;
}
}
}
// randomly chooses a colour from the colour library
color getColour() {
color randomColour = colours[ renderColourIndex ];
color newColour = color( red(randomColour), green(randomColour), blue(randomColour), discAlpha );
return newColour;
}
// calculate a random direction and speed for the spark
PVector getRandomVector() {
float angle = random(0, 2) * PI;
float velocity = random( 0, maxStartingVelocity );
float x = cos(angle) * velocity;
float y = sin(angle) * velocity;
PVector vector = new PVector( x, y );
return vector;
}
}