void setup(){
  size(700,400);
  smooth();
  background(398);
  frameRate(50);
}

void draw(){
  stroke(mouseX,0,mouseY);
  float distance= dist(pmouseX,pmouseY,mouseX,mouseY);
  float maxStroke=30;
  strokeWeight(maxStroke-constrain(distance,0,maxStroke));
  ellipse(mouseX,mouseY,mouseX,mouseY);
}

void mouseClicked(){
  rectMode(CENTER);
  fill(mouseY,255,mouseX);
  noStroke();
  rect(mouseX,mouseY,60,60);
}

void keyPressed(){
  background(390);
}
               



segundo

void setup(){

size(700,400);

smooth();

background(0);

frameRate(30);

}

void draw(){

stroke(mouseX,0,mouseY);

float distance= dist(pmouseX,pmouseY,mouseX,mouseY);

float maxStroke=15;

strokeWeight(maxStroke-constrain(distance,0,maxStroke));

line(pmouseX,pmouseY,mouseX,mouseY);

}

void mouseClicked(){

rectMode(CENTER);

fill(mouseY,255,mouseX);

noStroke();

rect(mouseX,mouseY,50,50);

}

void keyPressed(){

background(0);

}