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If you take a look at certain Lua files (for instance ego_detailmonitor/menu_map.lua or ego_detailmonitor/menu_missionbriefing.lua, you will find sections on top a file looking like this:
| Code Block | ||||||
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-- ffi setup
local ffi = require("ffi")
local C = ffi.C
ffi.cdef[[
typedef uint64_t UniverseID;
typedef struct {
const char* factionName;
const char* factionIcon;
} OwnerDetails;
UniverseID AddHoloMap(const char* texturename, float x0, float x1, float y0, float y1);
void ClearHighlightMapComponent(UniverseID holomapid);
const char* GetBuildSourceSequence(UniverseID componentid);
const char* GetComponentClass(UniverseID componentid);
const char* GetComponentName(UniverseID componentid);
uint64_t GetContextByClass(UniverseID componentid, const char* classname, bool includeself);
uint64_t GetMapComponentBelowCamera(UniverseID holomapid);
const char* GetMapShortName(UniverseID componentid);
OwnerDetails GetOwnerDetails(UniverseID componentid);
uint64_t GetParentComponent(UniverseID componentid);
uint64_t GetPickedMapComponent(UniverseID holomapid);
bool IsComponentOperational(UniverseID componentid);
bool IsInfoUnlockedForPlayer(UniverseID componentid, const char* infostring);
bool IsSellOffer(UniverseID tradeofferdockid);
void RemoveHoloMap(UniverseID holomapid);
void SetHighlightMapComponent(UniverseID holomapid, UniverseID componentid, bool resetplayerpan);
void ShowUniverseMap(UniverseID holomapid, UniverseID componentid, bool resetplayerzoom, int overridezoom);
void StartPanMap(UniverseID holomapid);
void StartRotateMap(UniverseID holomapid);
void StopPanMap(UniverseID holomapid);
void StopRotateMap(UniverseID holomapid);
void ZoomMap(UniverseID holomapid, float zoomstep);
]] |
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To be able to call FFI-functions, the following header should be placed at the top of the Lua script:
| Code Block | ||
|---|---|---|
| ||
local ffi = require("ffi")
local C = ffi.C
ffi.cdef[[
-- add FFI-functions here
]] |
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A call to the actual function then looks like this
| Code Block | ||
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local component = C.GetPickedMapComponent(myholomap) -- note the "C." prefix here which refers to the local C = ffi.C specified in the header [...] local details = C.GetOwnerDetails(componentID) local faction = ffi.string(details.factionName) local icon = ffi.string(details.factionIcon |
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In some cases you don't know what kind of ID you are being passed. To determine whether a variable is an FFI-ID, you can use the follow code
| Code Block | ||
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-- ffi setuplocalsetup local ffi = require("ffi") ffi.cdef[[ typedef uint64_t UniverseID; ]] [...] local myUniverseID = [...] [...] local ffiIDType = ffi.typeof("UniverseID") local isFFIID = ffi.istype(ffiIDType, myUniverseID) -- isFFIID will be true, if myUniverseID is an FFIID, otherwise this will be false |
In exceptional cases you might also have to create FFI datatypes directly in the Lua script. Normally this is not necessary, since passing certain Lua values to FFI will be converted to the appropriate type directly. However, in cases where you have to construct objects of an FFI type, you can do so using ffi.new
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local myFFIObject = ffi.new("UniverseID", 123) |
The code above will create an object of type UniverseID and initialize it with the value of 123.