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AP_Terrain: added some helper functions

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this adds easier to use helper functions for terrain handling
This commit is contained in:
Andrew Tridgell 2014-07-24 16:28:40 +10:00
parent d18c00d6fc
commit 18974363d5
2 changed files with 33 additions and 10 deletions
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31
libraries/AP_Terrain/AP_Terrain.cpp
View File

@ -145,7 +145,7 @@ bool AP_Terrain::height_amsl(const Location &loc, float &height)
return false is terrain at the given location or at home
location is not available
*/
bool AP_Terrain::height_terrain_difference(const Location &loc, float &terrain_difference)
bool AP_Terrain::height_terrain_difference_home(const Location &loc, float &terrain_difference)
{
float height_home, height_loc;
if (!height_amsl(ahrs.get_home(), height_home)) {
@ -170,16 +170,33 @@ bool AP_Terrain::height_terrain_difference(const Location &loc, float &terrain_d
return false if terrain data is not available either at the given
location or at the home location.
*/
bool AP_Terrain::height_above_terrain(const Location &loc, float relative_altitude, float &terrain_altitude)
bool AP_Terrain::height_above_terrain(const Location &loc, float relative_home_altitude, float &terrain_altitude)
{
float terrain_difference;
if (!height_terrain_difference(loc, terrain_difference)) {
if (!height_terrain_difference_home(loc, terrain_difference)) {
return false;
}
terrain_altitude = relative_altitude - terrain_difference;
terrain_altitude = relative_home_altitude - terrain_difference;
return true;
}
/*
return estimated height above the terrain given a relative-to-home
altitude (such as a barometric altitude) for a given location
return false if terrain data is not available either at the given
location or at the home location.
*/
bool AP_Terrain::height_above_terrain(const Location &loc, float &terrain_altitude)
{
float relative_home_altitude = loc.alt;
if (!loc.flags.relative_alt) {
// loc.alt has home altitude added, remove it
relative_home_altitude -= ahrs.get_home().alt*0.01f;
}
return height_above_terrain(loc, relative_home_altitude, terrain_altitude);
}
/*
return estimated equivalent relative-to-home altitude in meters of
a given height above the terrain for a given location.
@ -192,13 +209,13 @@ bool AP_Terrain::height_above_terrain(const Location &loc, float relative_altitu
return false if terrain data is not available either at the given
location or at the home location.
*/
bool AP_Terrain::height_relative_equivalent(const Location &loc, float terrain_altitude, float &relative_altitude)
bool AP_Terrain::height_relative_home_equivalent(const Location &loc, float terrain_altitude, float &relative_home_altitude)
{
float terrain_difference;
if (!height_terrain_difference(loc, terrain_difference)) {
if (!height_terrain_difference_home(loc, terrain_difference)) {
return false;
}
relative_altitude = terrain_altitude + terrain_difference;
relative_home_altitude = terrain_altitude + terrain_difference;
return true;
}

12
libraries/AP_Terrain/AP_Terrain.h
View File

@ -109,7 +109,7 @@ public:
return false is terrain at the given location or at home
location is not available
*/
bool height_terrain_difference(const Location &loc, float &terrain_difference);
bool height_terrain_difference_home(const Location &loc, float &terrain_difference);
/*
return estimated equivalent relative-to-home altitude in meters
@ -123,7 +123,7 @@ public:
return false if terrain data is not available either at the given
location or at the home location.
*/
bool height_relative_equivalent(const Location &loc, float terrain_altitude, float &relative_altitude);
bool height_relative_home_equivalent(const Location &loc, float terrain_altitude, float &relative_altitude);
/*
return estimated height above the terrain in meters given a
@ -133,7 +133,13 @@ public:
return false if terrain data is not available either at the given
location or at the home location.
*/
bool height_above_terrain(const Location &loc, float relative_altitude, float &terrain_altitude);
bool height_above_terrain(const Location &loc, float relative_home_altitude, float &terrain_altitude);
/*
alternative interface to height_above_terrain where
relative_altitude is taken from loc.alt (in centimeters)
*/
bool height_above_terrain(const Location &loc, float &terrain_altitude);
private:
// allocate the terrain subsystem data