forked from mpusz/mp-units
b982921d27
Now References can be disabled to meassure a compile time impact. Also the same examples are now provided in two subdirectories to be able to easily compare the pros and cons of every quantity construction technique.
82 lines
3.2 KiB
ReStructuredText
82 lines
3.2 KiB
ReStructuredText
.. namespace:: units
|
|
|
|
glide_computer
|
|
==============
|
|
|
|
This example presents the usage of:
|
|
|
|
- `quantity_point` to mark "absolute" quantities like ``timestamp``
|
|
- `quantity_point_kind` to mark "absolute" kinds of quantities like ``altitude`` (as opposed to ``height``),
|
|
- different kinds for length, time, and speed,
|
|
- the use of quantity kinds to show how to handle 3D space for aviation needs,
|
|
- unit constants to initialize the database
|
|
- quantities text output formatting,
|
|
- cooperation with `std::chrono`.
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer.h
|
|
:caption: glide_computer.h
|
|
:start-at: #include
|
|
:end-before: using namespace units;
|
|
:linenos:
|
|
:lineno-match:
|
|
|
|
The use of `quantity_kind` and `quantity_point_kind` provides strong typing
|
|
that divide quantities and quantity points to the ones on a horizontal (X, Y) plane and vertical (Z) axis.
|
|
Their purpose is to make different kinds of quantity
|
|
(i.e. length) separate strong types (i.e. distance, height).
|
|
Additionally, separating a quantity from its quantity point
|
|
means that we can define a ``height`` and ``altitude`` as different strong types.
|
|
A quantity point provides a more restricted interface meant for absolute calculations.
|
|
|
|
The glide calculator engine also take benefits from different :term:`kinds of quantities <kind>`.
|
|
For example we have 3 for a quantity of length:
|
|
|
|
- ``distance`` - a relative horizontal distance between 2 points on Earth
|
|
- ``height`` - a relative altitude difference between 2 points in the air
|
|
- ``altitude`` - an absolute altitude value measured form the mean sea level (AMSL).
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer.h
|
|
:caption: glide_computer.h
|
|
:start-at: using namespace units;
|
|
:end-before: // text output
|
|
:linenos:
|
|
:lineno-match:
|
|
|
|
Next a custom text output is provided both for C++ output streams and the text formatting facility.
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer.h
|
|
:caption: glide_computer.h
|
|
:start-at: // text output
|
|
:end-before: // definition of glide computer databases and utilities
|
|
:linenos:
|
|
:lineno-match:
|
|
|
|
The engine of this simple glide computer works on quantities of the SI units with a floating-point
|
|
representation. The user can pass any unit valid for a given quantity and the library will automatically
|
|
convert it to the one required by the engine interface.
|
|
|
|
The glide calculator takes task created as a list of waypoints, glider performance data, weather conditions,
|
|
safety constraints, and a towing height.
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer.h
|
|
:caption: glide_computer.h
|
|
:start-at: // definition of glide computer databases and utilities
|
|
:linenos:
|
|
:lineno-match:
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer_example.cpp
|
|
:caption: glide_computer_example.cpp
|
|
:start-at: #include
|
|
:linenos:
|
|
:lineno-match:
|
|
|
|
Having all of that it estimates the number of flight phases (towing, circling, gliding, final glide)
|
|
needed to finish a task. As an output it provides the duration needed to finish the task while
|
|
flying a selected glider in the specific weather conditions.
|
|
|
|
.. literalinclude:: ../../example/references/glide_computer.cpp
|
|
:caption: glide_computer.cpp
|
|
:start-at: #include
|
|
:linenos:
|
|
:lineno-match:
|