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src/Instrumentation/tcas.*: condensed checking of transponder.

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Transponder-checking code is now done in new static function
checkTransponderLocal() which also sets altitude via an out-param. This
avoids duplicate string comparisons in the previous checkTransponder() and
getAltitude() functions.

Also check for controls/invisible for all aircraft, which could allow ignoring
of AI and Swift aircraft in future.

TCAS::ThreatDetector::checkTransponder() now simply calls
checkTransponderLocal() with a dummy altitude out-param; it doesn't appear to
be used so could probably be removed.
This commit is contained in:
Julian Smith 2021-09-19 10:39:33 +01:00
parent 9b05b2f941
commit 3e7e970e5d
2 changed files with 28 additions and 37 deletions
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64
src/Instrumentation/tcas.cxx
View file

@ -581,44 +581,36 @@ TCAS::ThreatDetector::update(void)
tcas->advisoryGenerator.setAlarmThresholds(pAlarmThresholds);
}
// If plane's transponder is enabled, return true with o_altFt set to
// altitude. Otherwise return false.
//
static bool checkTransponderLocal(const SGPropertyNode* pModel, float velocityKt, float& o_altFt)
{
if (pModel->getBoolValue("controls/invisible", false /*default*/))
{
// For MP aircraft (name='multiplayer') that are being ignored.
return false;
}
if (pModel->getNameString() == "aircraft")
{
/* assume all non-MP and non-Swift (i.e. AI) aircraft have their transponder switched off while taxiing/parking
* (at low speed) */
if (velocityKt < 40.0) return false;
o_altFt = pModel->getDoubleValue("position/altitude-ft");
return true;
}
o_altFt = pModel->getIntValue("instrumentation/transponder/altitude", -9999);
// must have Mode C (altitude) transponder to be visible.
// "-9999" is a special value used by src/Instrumentation/transponder.cxx to indicate the non-transmission of a value.
return (o_altFt != -9999);
}
/** Check if plane's transponder is enabled. */
bool
TCAS::ThreatDetector::checkTransponder(const SGPropertyNode* pModel, float velocityKt)
{
const string name = pModel->getName();
if (name == "aircraft")
{
/* assume all non-MP and non-Swift aircraft have their transponder switched off while taxiing/parking
* (at low speed) */
return velocityKt >= 40.0;
}
else if (pModel->getIntValue("instrumentation/transponder/altitude", -9999) != -9999)
{
// must have Mode C (altitude) transponder to be visible.
// "-9999" is a special value used by src/Instrumentation/transponder.cxx to indicate the non-transmission of a value.
if (name == "multiplayer")
{
// ignored MP plane: pretend transponder is switched off
return !(pModel->getBoolValue("controls/invisible"));
}
if (name == "swift"){
return true;
}
}
// assume non-MP/non-AI planes (e.g. ships) have no transponder
return false;
}
/** Get altitude reported by transponder. */
float
TCAS::ThreatDetector::getAltitude(const SGPropertyNode* pModel)
{
const string name = pModel->getName();
if (name == "multiplayer" || name == "swift")
{
return pModel->getIntValue("instrumentation/transponder/altitude");
}
return pModel->getDoubleValue("position/altitude-ft");
float altFt;
return checkTransponderLocal(pModel, velocityKt, altFt);
}
/** Check if plane is a threat. */
@ -633,11 +625,11 @@ TCAS::ThreatDetector::checkThreat(int mode, const SGPropertyNode* pModel)
float velocityKt = pModel->getDoubleValue("velocities/true-airspeed-kt");
if (!checkTransponder(pModel, velocityKt))
float altFt;
if (!checkTransponderLocal(pModel, velocityKt, altFt))
return ThreatInvisible;
int threatLevel = ThreatNone;
float altFt = getAltitude(pModel);
currentThreat.relativeAltitudeFt = altFt - self.pressureAltFt;
// save computation time: don't care when relative altitude is excessive

1
src/Instrumentation/tcas.hxx
View file

@ -317,7 +317,6 @@ class TCAS : public SGSubsystem
void update (void);
bool checkTransponder (const SGPropertyNode* pModel, float velocityKt);
float getAltitude (const SGPropertyNode* pModel);
int checkThreat (int mode, const SGPropertyNode* pModel);
void checkVerticalThreat (void);
void horizontalThreat (float bearing, float distanceNm, float heading,