function visibility:load(xmlFile)

numparts = Utils.getNoNil(getXMLInt(xmlFile, "vehicle.parts#count"), 0);
self.parts = {};
for i=1, numparts do
local partnamei = string.format("vehicle.parts.part%d", i);
self.parts[i] = Utils.indexToObject(self.components, getXMLString(xmlFile, partnamei .. "#index"));
setVisibility(self.parts[i], false);
end;
self.partsActive = false;

numparts2 = Utils.getNoNil(getXMLInt(xmlFile, "vehicle.parts2#count"), 0);
self.parts2 = {};
for i=1, numparts2 do
local partnamei = string.format("vehicle.parts2.part%d", i);
self.parts2[i] = Utils.indexToObject(self.components, getXMLString(xmlFile, partnamei .. "#index"));
setVisibility(self.parts2[i], false);
end;
self.parts2Active = false;

end;

function visibility:keyEvent(unicode, sym, modifier, isDown)

if isDown and sym == Input.KEY_k then
self.partsActive = not self.partsActive;
end;
if isDown and sym == Input.KEY_l then
self.parts2Active = not self.parts2Active;
end;

end;

function visibility:update(dt)

if self.partsActive then
for i=1, numparts do
setVisibility(self.parts[i], self.partsActive);
end;
else
for i=1, numparts do
setVisibility(self.parts[i], self.partsActive, false);
end;
end;
if self.parts2Active then
for i=1, numparts2 do
setVisibility(self.parts2[i], self.parts2Active);
end;
else
for i=1, numparts2 do
setVisibility(self.parts2[i], self.parts2Active, false);
end;
end;
end;