int thickness = 5;
void setup() {
  size(200,200);
  noStroke();
  strokeWeight(thickness);
  ellipseMode(CENTER_RADIUS);
}
float x=0;
void loop() {
noStroke();
  fill(128,5);
  rect(0,0,width,height);

}
void mouseDragged() {
mouseMoved();
}
void mouseMoved() {
//  int size = 1;
//  rect(mouseX/size*size,mouseY/size*size,size,size);
  stroke(255);
line (pmouseX,pmouseY,mouseX,mouseY);
noStroke();
fill(255);
ellipse(pmouseX, pmouseY, thickness, thickness);
ellipse(mouseX, mouseY, thickness, thickness);
}