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Improved accuracy of HandleGetT terrain probe

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Follow the process in the following post to get accurate results:
// https://forums.x-plane.org/index.php?/forums/topic/38688-how-do-i-use-xplmprobeterrainxyz/&page=2

Also added the ground velocity vector to the output.  This is used for carrier landing where "ground" is moving.
This commit is contained in:
Norman Princen
2020-04-19 13:33:00 -07:00
parent a3175a8180
commit f630dbdf07
1 changed files with 56 additions and 32 deletions
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88
xpcPlugin/MessageHandlers.cpp
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@@ -642,49 +642,70 @@ namespace XPC
unsigned char aircraft = buffer[5];
Log::FormatLine(LOG_TRACE, "GETT", "Getting terrain information for aircraft %u", aircraft);
double loc[3];
double X;
double Y;
double Z;
memcpy(loc, buffer + 6, 24);
double pos[3];
memcpy(pos, buffer + 6, 24);
if(loc[0] == -998 || loc[1] == -998 || loc[2] == -998)
{
// get terrain properties at aircraft location
// probe needs to be below terrain to work...
X = DataManager::GetDouble(DREF_LocalX, aircraft);
Z = DataManager::GetDouble(DREF_LocalZ, aircraft);
Y = -100.0;
}
else
{
// terrain probe at specified location
XPLMWorldToLocal(loc[0], loc[1], loc[2], &X, &Y, &Z);
pos[0] = DataManager::GetDouble(DREF_Latitude, aircraft);
pos[1] = DataManager::GetDouble(DREF_Longitude, aircraft);
pos[2] = 0.0;
}
MessageHandlers::SendTerr(pos, aircraft);
}
void MessageHandlers::SendTerr(double pos[3], char aircraft)
{
double lat, lon, alt, X, Y, Z;
// Init terrain probe (if required) and probe data struct
XPLMProbeInfo_t probe_data;
static XPLMProbeInfo_t probe_data;
probe_data.structSize = sizeof(XPLMProbeInfo_t);
if(Terrain_probe == nullptr)
{
Log::FormatLine(LOG_TRACE, "GETT", "Create terrain probe for aircraft %u", aircraft);
Log::FormatLine(LOG_TRACE, "TERR", "Create terrain probe for aircraft %u", aircraft);
Terrain_probe = XPLMCreateProbe(0);
}
// terrain probe at specified location
// Follow the process in the following post to get accurate results
// https://forums.x-plane.org/index.php?/forums/topic/38688-how-do-i-use-xplmprobeterrainxyz/&page=2
// transform probe location to local coordinates
// Step 1. Convert lat/lon/0 to XYZ
XPLMWorldToLocal(pos[0], pos[1], pos[2], &X, &Y, &Z);
// query probe
// Step 2. Probe XYZ to get a new Y
int rc = XPLMProbeTerrainXYZ(Terrain_probe, X, Y, Z, &probe_data);
if(rc > 0)
{
Log::FormatLine(LOG_ERROR, "TERR", "Probe failed. Return Value %u", rc);
XPLMDestroyProbe(Terrain_probe);
return;
}
// transform probe location to world coordinates
double lat;
double lon;
double alt;
// Step 3. Convert that new XYZ back to LLE
XPLMLocalToWorld(probe_data.locationX, probe_data.locationY, probe_data.locationZ, &lat, &lon, &alt);
Log::FormatLine(LOG_TRACE, "TERR", "Conv LLA=%f, %f, %f", lat, lon, alt);
// transform probe location to local coordinates
// Step 4. NOW convert your origina lat/lon with the elevation from step 3 to XYZ
XPLMWorldToLocal(pos[0], pos[1], alt, &X, &Y, &Z);
// query probe
// Step 5. Re-probe with the NEW XYZ
rc = XPLMProbeTerrainXYZ(Terrain_probe, X, Y, Z, &probe_data);
if(rc == 0)
{
// transform probe location to world coordinates
// Step 6. You now have a new Y, and your XYZ will be closer to correct for high elevations far from the origin.
XPLMLocalToWorld(probe_data.locationX, probe_data.locationY, probe_data.locationZ, &lat, &lon, &alt);
Log::FormatLine(LOG_TRACE, "GETT", "Probe LLA %lf %lf %lf", lat, lon, alt);
Log::FormatLine(LOG_TRACE, "TERR", "Probe LLA %lf %lf %lf", lat, lon, alt);
}
else
{
@@ -692,31 +713,34 @@ namespace XPC
lon = -998;
alt = -998;
Log::FormatLine(LOG_TRACE, "GETT", "Probe failed. Return Value %u", rc);
Log::FormatLine(LOG_TRACE, "TERR", "Probe failed. Return Value %u", rc);
}
// keep probe for next query
// XPLMDestroyProbe(probe);
// XPLMDestroyProbe(Terrain_probe);
// Assemble response message
unsigned char response[50] = "TERR";
unsigned char response[62] = "TERR";
response[5] = aircraft;
// terrain height over msl at lat/lon point
memcpy(response + 6, &lat, 8);
memcpy(response + 14, &lon, 8);
memcpy(response + 22, &alt, 8);
// terrain incidence
// terrain normal vector
memcpy(response + 30, &probe_data.normalX, 4);
memcpy(response + 34, &probe_data.normalY, 4);
memcpy(response + 38, &probe_data.normalZ, 4);
// terrain velocity
memcpy(response + 42, &probe_data.velocityX, 4);
memcpy(response + 46, &probe_data.velocityY, 4);
memcpy(response + 50, &probe_data.velocityZ, 4);
// terrain type
memcpy(response + 42, &probe_data.is_wet, 4);
memcpy(response + 54, &probe_data.is_wet, 4);
// probe status
memcpy(response + 46, &rc, 4);
sock->SendTo(response, 50, &connection.addr);
}
memcpy(response + 58, &rc, 4);
sock->SendTo(response, 62, &connection.addr);
}
void MessageHandlers::HandleSimu(const Message& msg)
{