clamp method
Implementation
Vector4 clamp(Vector4 min, Vector4 max) {
// assumes min < max, componentwise
x = Math.max(min.x, Math.min(max.x, x));
y = Math.max(min.y, Math.min(max.y, y));
z = Math.max(min.z, Math.min(max.z, z));
w = Math.max(min.w, Math.min(max.w, w));
return this;
}