var c2 = 255

​

function setup() {

    createCanvas(displayWidth*1.5, displayHeight  *1.5).mouseMoved(changeColor);

    noStroke();

}

​

function draw() {

    background(0);

    fill(c1);

    rect(0, 0, width / 2, height);

    fill(c2);

    rect(width / 2, 0, width / 2, height);

}

​

function changeColor() {

    console.log(mouseX);

    if (mouseX < width / 2)

        c1 = map(mouseX, 0, width / 2, 0, 255);

    else

        c2 = map(mouseX, width / 2, width, 0, 255);

​

}