float s, sNorm, lineY, squareX, squareSize;
color Clr;
float mouseXNorm = 0;

void setup(){
size(400,200);
noFill();
rectMode(CENTER);
lineY=height;
squareSize=20;
Clr=color(255,0,0);
}

void draw(){
background(0);
mouseXNorm = mouseX/float(width);
s = sin(mouseXNorm*TWO_PI*2);
sNorm = (s+1)/2;
squareX = (sNorm*180.)+110;
rect(squareX,100,squareSize,squareSize);
stroke(255,80);
line(100,0,100,lineY);
line(300,0,300,lineY);
stroke(Clr);
line(mouseX,0,mouseX,lineY);
}