Tail.pde
class Tail {
PVector now;
PVector[] past;
float border = 12;
Tail() {
now = PVector.random2D();
now.mult((width - (border * 2)));
past = new PVector[100];
for(int i = 0; i < past.length; i++) {
past[ i ] = new PVector();
past[ i ] = now.copy();
}
}
void update() {
PVector direction = PVector.random2D();
direction.mult( random(5, 15) );
now.add(direction);
if(now.x > (width - border)) {
now.x -= (now.x - (width - border));
} else if(now.x < border) {
now.x = (border + (border - now.x));
}
if(now.y > (height - border)) {
now.y -= (now.y - (height - border));
} else if(now.y < border) {
now.y = (border + (border - now.y));
}
}
color colorAt(float cax, float cay) {
return color(
map(cax, border, (width - border), 0, 255),
map(cay, border, (height - border), 0, 255),
map((cax * cay), (border * border), ((width - border) * (height - border)), 0, 255)
);
}
void draw() {
//pushMatrix();
pushStyle();
// tail
beginShape();
stroke(colorAt(now.x, now.y));
strokeWeight(2);
noFill();
curveVertex(now.x, now.y);
boolean opened = true;
for(int i = 0; i < past.length; i++) {
curveVertex(past[ i ].x, past[ i ].y);
if((i % 3) == 0) {
endShape();
popStyle();
opened = false;
if(i < (past.length - 1)) {
opened = true;
pushStyle();
beginShape();
stroke(colorAt(past[ i ].x, past[ i ].y));
strokeWeight(2);
noFill();
curveVertex(past[ i ].x, past[ i ].y);
}
}
}
if(opened) {
endShape();
popStyle();
}
// dot
pushStyle();
ellipseMode(CENTER);
fill(colorAt(now.x, now.y));
noStroke();
ellipse(now.x, now.y, 8, 8);
popStyle();
//popMatrix();
// reverse set tail values so the first value is ready to be set to $now
float min_x = float(width);
float min_y = float(height);
float max_x = 0;
float max_y = 0;
for(int i = (past.length - 2); i >= 0; i--) {
past[ (i + 1) ] = past[ i ].copy();
min_x = min(min_x, past[ (i + 1) ].x);
min_y = min(min_y, past[ (i + 1) ].y);
max_x = max(max_x, past[ (i + 1) ].x);
max_y = max(max_y, past[ (i + 1) ].y);
}
past[0] = now.copy();
min_x = min(min_x, now.x);
min_y = min(min_y, now.y);
max_x = max(max_x, now.x);
max_y = max(max_y, now.y);
// outer box
pushStyle();
stroke(color(100));
strokeWeight(2);
noFill();
rect(
(min_x - 3),
(min_y - 3),
((max_x - min_x) + 6),
((max_y - min_y) + 6)
);
popStyle();
}
}
