Class: TRootMatrixState

Declaration: MatrixState.h

Taxonomy Categories:

Member Functions:

TRootMatrixState
~TRootMatrixState
GetMatrix
GetSharedTimeStampState

Interface Category:

API.

Inherits From:

TMatrixState

Inherited By:

None.

Purpose:

TRootMatrixState is a concrete class, derived from TMatrix3DState, that is ideal for the root 2-D matrix state of a graphic hierarchy. The class supplies the 2-D identity matrix and its own shared time stamp. The TRootGrafState class uses a TRootMatrixState to represent the default matrix state. To create a hierarchy, link TLinkableMatrixState objects to a TRootMatrixState object by passing it as an argument to their LinkTo member functions.

Instantiation:

Allocate on the heap or the stack.

Deriving Classes:

None.

Concurrency:

Not multithread safe.

Resource Use:

No special requirements.

Member Function: TRootMatrixState::TRootMatrixState

TRootMatrixState ()
TRootMatrixState (const TRootMatrixState &)

Interface Category:

API.

Purpose:

Default constructor.
Copy constructor.

Calling Context:

Called by the stream-in operators. You can also call this function directly.
Called to copy an object.

Parameters:

Takes no parameters.
const TRootMatrixState & -The object to be copied.

Return Value:

None.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

Member Function: TRootMatrixState::~TRootMatrixState

virtual ~ TRootMatrixState ()

Interface Category:

API.

Purpose:

Destructor.

Calling Context:

Called to destroy an object.

Parameters:

Takes no parameters.

Return Value:

None.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

Member Function: TRootMatrixState::GetMatrix

virtual const TGrafMatrix * GetMatrix () const

Interface Category:

API.

Purpose:

Returns a constant pointer to an identity matrix.

Calling Context:

Call this function directly.

Parameters:

Takes no parameters.

Return Value:

Returns a constant pointer to a TGrafMatrix object that represents the identity matrix for this object.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

Member Function: TRootMatrixState::GetSharedTimeStampState

virtual TTimeStampState * GetSharedTimeStampState () const

Interface Category:

API.

Purpose:

Returns the value of the time stamp that is shared by the objects within this hierarchy. A state object's value is typically dependent on its parent's value. This means that when an object's value is queried, it must check to see if its parent's state has changed, and its parent must do the same, until it reaches the root of the hierarchy. Because state queries are done quite often, such as in a rendering process, shared time stamp states were invented to improve the performance of noticing whether some state in the hierarchy has changed. GetSharedTimeStampState returns a pointer to an object that contains a single time stamp that changes whenever any part of the hierarchy changes. An object can tell if any of the hierarchy above it has changed by looking at the shared time stamp, instead of looking at its parent's time stamp, causing the parent to look at its parent's time stamp, and so on.

Calling Context:

Call this function directly.

Parameters:

Takes no parameters.

Return Value:

Returns a pointer to a TTimeStampState object that represents the last modification time of any object in this hierarchy.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

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