var xPos = 0; var yPos = 0; var pixelSize = 40; var drawBackground = function() { noStroke(); background(128, 187, 231); fill(118, 74, 47); rect(0, 100, 400, 400); fill(102, 150, 88); rect(0, 100, 400, 50); }; drawBackground(); var draw = function() { if(mouseIsPressed) { xPos = floor(mouseX/ pixelSize) * pixelSize; yPos = floor(mouseY/ pixelSize) * pixelSize; fill(128, 186, 231); rect(xPos, yPos, pixelSize, pixelSize); } };