clone = {
const clone = canvas.getContext('2d').getImageData(0, 0, 512, 512);
for (let i = 0; i < clone.data.length; i += 4) {
let sum = (clone.data[i] * 256 + clone.data[i + 1] + clone.data[i + 2] / 256);
sum = (sum - seabed) / extrude;
clone.data[i] = clone.data[i + 1] = clone.data[i + 2] = sum;
}
return clone;
}