/* built with Studio Sketchpad: 
 *   https://sketchpad.cc
 * 
 * observe the evolution of this sketch: 
 *   https://studio.sketchpad.cc/sp/pad/view/ro.uF$uvk8veLr/rev.2861
 * 
 * authors: 
 *   Matthew

 * license (unless otherwise specified): 
 *   creative commons attribution-share alike 3.0 license.
 *   https://creativecommons.org/licenses/by-sa/3.0/ 
 */ 



float i = 0.0;
float x;
float y;
float wobbleX = 0.0;
float wobbleY = 0.0;
int fadeCounter = 0;
color bg = color(230);
float[] ink = new float[20];
float[] spread = new float[3];

void setup() {     
    background(bg);
    size(300, 300); 
    smooth();
    frameRate(60);
    fill(0);
    noStroke();
    x = width/2;
    y = height/2;
    
    for (int j = 0; j < 30; j++)
        ink[j] = random(1.0,2.0);
    spread[0] = 6.0;
    spread[1] = 4.0;
    spread[2] = 2.0;
} 

void draw() {  // this is run repeatedly.  
    if (fadeCounter % 30 == 0) {
        fill(bg,6);
        rect(0,0,width,height);
    }
    fadeCounter++;

    newPosition();
    brush();
}

void brush() {
    for (float c = 0.0; c <= 2; c += 0.2) {
        bristle(spread[0], 0.5 * c * PI, x, y, ink[int(c)]);
        bristle(spread[1], c * PI, x, y, ink[int(c)+10]);
        bristle(spread[2], 2.0 * c * PI, x, y, ink[int(c)+20]);
    }
    for (int j = 0; j < 30; j++)
        ink[j] = constrain(ink[j]+random(-0.125,0.125),0.25,3);
    for (int j = 0; j < 3; j++)
        spread[j] = constrain(spread[j] + random(-0.125,0.125),5 - (2.4 * j), 8 - (2.5 * j));
}

void bristle(float radius, float theta, float xPos, float yPos, float bw) {
    fill(32,64);
    ellipse(radius * sin(-1 * theta) + xPos,
            radius * cos(-1 * theta) + yPos,
            bw, bw);
}

void newPosition() {
    wobbleX = constrain(wobbleX + random(-0.35, 0.35), -25, 25);
    wobbleY = constrain(wobbleY + random(-0.35, 0.35), -25, 25);
    x = 75 * sin(-0.2 * i) + width/2 + wobbleX;
    y = 75* cos(-0.2 * i) + height/2 + wobbleY;
    i += 0.06;
}