Defining the Projection
The projection is defined in the file proj_step1.cpp
To define the class, you use the
IlvMapsDefineBasicProjectionIO macro. This macro defines the function and static members that are necessary to support input and output operations. It also generates code to initialize the
IlvProjectionClassInfo.
#include "proj_step1.h"
IlvMapsDefineBasicProjectionIO(Mercator,
IlvProjection,
"My Mercator Implementation",
new Mercator(),
IlvMapsEmptyStatement());
The first argument of the macro is the name of the projection class.
The second argument is the name of the superclass of the projection.
The fourth argument is the statement used to create a new instance of this class.
The last argument is a statement that will be called during the initialization of the projection class. Since nothing specific is done in this example, the
IlvMapsEmptyStatement macro is used. This last parameter will be used in steps 2 and 3.
Now the projection constructor must be defined. This constructor calls the constructor of its superclass
IlvProjection, which takes three arguments.
The first argument is an
IlBoolean value specifying whether the projection supports nonspherical ellipsoids. In our example, this argument is set to
IlTrue since the projection supports the equations for nonspherical ellipsoids.
The second argument is an
IlvBoolean value indicating whether the projection supports an inverse function. In our example, this argument is set to
IlTrue since the projection supports an inverse function.
The third argument is an
enum value that indicates the geometric properties of the projection. In our example this argument is
IlvConformalProjectionGeometricProperty since the Mercator projection is conformal.
You must also define a copy constructor that is declared by the IlvMapsDeclareProjectionIO macro.
Mercator::Mercator()
:IlvProjection(IlTrue,
IlTrue,
IlvConformalProjectionGeometricProperty)
{
}
Mercator::Mercator(const Mercator& source)
:IlvProjection(source)
{
}
Version 6.1
Copyright © 2016, Rogue Wave Software, Inc. All Rights Reserved.