agi.foundation.access.constraints

(agi.foundation.platforms-2024r3.jar)

Class CentralBodyObstructionConstraint

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.access.AccessQuery

agi.foundation.access.AccessConstraint

agi.foundation.access.constraints.CentralBodyObstructionConstraint

All Implemented Interfaces:

ILinkConstraint, ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public class CentralBodyObstructionConstraint
extends AccessConstraint
implements ILinkConstraint

An Access constraint that requires that the view from one object to another not be obstructed by a central body such as the Earth or another planet. Only the spheroidal shape of the central body is considered. That is, terrain and the mean sea level surface are NOT considered.

This constraint requires that both ends of the ConstrainedLink (get / set) provide ILocationPointService.

After obtaining the positions of the two objects in the fixed frame, this constraint uses Ellipsoid.getDegreeOfObstruction(Cartesian,Cartesian) to determine whether the central body lies between the two points. When accounting for light-time delay, the constraint will iterate to find the position and orientation of the central body ellipsoid at the time when the photon is at its point of closest approach. This is done with respect to the observer specified when creating the AccessEvaluator, ConstrainedLinkEnd (get / set) is not used by this constraint.

Constructor Summary

Constructors

Modifier	Constructor and Description
	CentralBodyObstructionConstraint() Initializes a new instance with default values.
	CentralBodyObstructionConstraint(CentralBody centralBody) Initializes a new instance with the specified central body.
protected	CentralBodyObstructionConstraint(CentralBodyObstructionConstraint existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.
	CentralBodyObstructionConstraint(IServiceProvider constrainedLink, CentralBody centralBody) Initializes a new instance with the specified constrained link, constrained link end, and central body.

Method Summary

Modifier and Type	Method and Description
void	buildQueryEvaluator(ConstraintQueryBuilder builder, EvaluatorGroup group) Builds a query evaluator from this constraint.
protected boolean	checkForSameDefinition(AccessConstraint other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(CentralBodyObstructionConstraint other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
void	enumerateDependencies(DependencyEnumerator enumerator) Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon.
CentralBody	getCentralBody() Gets the central body to consider in this constraint.
IServiceProvider	getConstrainedLink() Gets the link to which this constraint applies.
LinkRole	getConstrainedLinkEnd() Gets the end of the link to which this constraint applies.
double	getTolerance() Gets the tolerance on the constraint value to use when computing the time when this constraint crosses its threshold.
void	setCentralBody(CentralBody value) Sets the central body to consider in this constraint.
void	setConstrainedLink(IServiceProvider value) Sets the link to which this constraint applies.
void	setConstrainedLinkEnd(LinkRole value) Sets the end of the link to which this constraint applies.
void	setTolerance(double value) Sets the tolerance on the constraint value to use when computing the time when this constraint crosses its threshold.
String	toString() Returns a string representation of the object.

Methods inherited from class agi.foundation.access.AccessConstraint

checkForSameDefinition, freezeAggregatedObjects, getApplicability, getEvaluationOrder, getEvaluator, getSampling, setApplicability, setEvaluationOrder, toDisjunctiveNormalForm

Methods inherited from class agi.foundation.access.AccessQuery

and, and, anyPath, anyPath, anyPath, anyPath, anyPath, anyPath, atLeastN, atMostN, checkForSameDefinition, exactlyN, fromObject, fromObjectAllowNoConstraints, getDebuggingLogger, getEvaluator, getEvaluator, not, or, or, setDebuggingLogger

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CentralBodyObstructionConstraint

public CentralBodyObstructionConstraint()

Initializes a new instance with default values.

This constructor initializes the CentralBody (get / set) property to the Earth (get) instance that is in the CentralBodiesFacet instance in the CalculationContext.

This constraint is ready for use as an AccessConstraintsExtension after being constructed using this constructor. However, before evaluating this constraint as part of an AccessQuery, it is also necessary to set the ConstrainedLink (get / set) property.

CentralBodyObstructionConstraint

public CentralBodyObstructionConstraint(CentralBody centralBody)

Initializes a new instance with the specified central body.

Before evaluating this constraint as part of an AccessQuery, it is necessary to set the ConstrainedLink (get / set) property.

This constraint is ready for use as an AccessConstraintsExtension after being constructed using this constructor. However, before evaluating this constraint as part of an AccessQuery, it is also necessary to set the ConstrainedLink (get / set) property.

Parameters:

centralBody - The central body which obstructs visibility.

CentralBodyObstructionConstraint

public CentralBodyObstructionConstraint(IServiceProvider constrainedLink,
                                        CentralBody centralBody)

Initializes a new instance with the specified constrained link, constrained link end, and central body.

Parameters:

constrainedLink - The link to which this constraint is applied.

centralBody - The central body which obstructs visibility.

CentralBodyObstructionConstraint

protected CentralBodyObstructionConstraint(@Nonnull
                                           CentralBodyObstructionConstraint existingInstance,
                                           @Nonnull
                                           CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Specified by:

clone in class DefinitionalObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected final boolean checkForSameDefinition(AccessConstraint other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Specified by:

checkForSameDefinition in class AccessConstraint

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

checkForSameDefinition

protected boolean checkForSameDefinition(CentralBodyObstructionConstraint other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the CentralBodyObstructionConstraint.checkForSameDefinition(agi.foundation.access.AccessConstraint) method.

Overrides:

computeCurrentDefinitionHashCode in class AccessConstraint

Returns:

The computed hash code.

enumerateDependencies

public void enumerateDependencies(DependencyEnumerator enumerator)

Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon. Derived classes which contain additional dependencies MUST override this method, call the base implementation, and enumerate dependencies introduced by the derived class.

Specified by:

enumerateDependencies in interface IEnumerateDependencies

Overrides:

enumerateDependencies in class AccessConstraint

Parameters:

enumerator - The enumerator that is informed of the dependencies of this object.

getCentralBody

public final CentralBody getCentralBody()

Gets the central body to consider in this constraint.

By default, the value of this property is the EarthCentralBody in the CentralBodiesFacet instance in the CalculationContext.

setCentralBody

public final void setCentralBody(CentralBody value)

Sets the central body to consider in this constraint.

By default, the value of this property is the EarthCentralBody in the CentralBodiesFacet instance in the CalculationContext.

getConstrainedLink

public final IServiceProvider getConstrainedLink()

Gets the link to which this constraint applies. It is not necessary to set this property when using this constraint with AccessComputation.

Specified by:

getConstrainedLink in interface ILinkConstraint

setConstrainedLink

public final void setConstrainedLink(IServiceProvider value)

Sets the link to which this constraint applies. It is not necessary to set this property when using this constraint with AccessComputation.

Specified by:

setConstrainedLink in interface ILinkConstraint

getConstrainedLinkEnd

@Nonnull
public final LinkRole getConstrainedLinkEnd()

Gets the end of the link to which this constraint applies.

This property can be ignored, as a CentralBodyObstructionConstraint applies to the link as a whole, not any particular object.

Specified by:

getConstrainedLinkEnd in interface ILinkConstraint

setConstrainedLinkEnd

public final void setConstrainedLinkEnd(@Nonnull
                                        LinkRole value)

Sets the end of the link to which this constraint applies.

This property can be ignored, as a CentralBodyObstructionConstraint applies to the link as a whole, not any particular object.

Specified by:

setConstrainedLinkEnd in interface ILinkConstraint

getTolerance

public final double getTolerance()

Gets the tolerance on the constraint value to use when computing the time when this constraint crosses its threshold.

setTolerance

public final void setTolerance(double value)

Sets the tolerance on the constraint value to use when computing the time when this constraint crosses its threshold.

toString

public String toString()

Description copied from class: java.lang.Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

buildQueryEvaluator

public void buildQueryEvaluator(ConstraintQueryBuilder builder,
                                EvaluatorGroup group)

Builds a query evaluator from this constraint.

Specified by:

buildQueryEvaluator in class AccessConstraint

Parameters:

builder - The builder instance to use to build the evaluator.

group - The evaluator group in which to create individual constraint function evaluators.