Generic 3D primitive description class.

See TBuffer3DTypes for producer classes.

Filling TBuffer3D and Adding to Viewer

The viewers behind the TVirtualViewer3D interface differ greatly in their capabilities e.g.

Some know how to draw certain shapes natively (e.g. spheres/tubes in OpenGL)
others always require a raw tessellation description of points/lines/segments.
Some need the 3D object positions in the global frame, others can cope with local frames + a translation matrix - which can give considerable performance benefits.

To cope with these situations the object buffer is filled out in negotiation with the viewer. TBuffer3D classes are conceptually divided into enumerated sections Core, BoundingBox, Raw etc (see TBuffer3D.h for more details).

The SectionsValid() / SetSectionsValid / ClearSectionsValid() methods of TBuffer3D are used to test/set/clear these section valid flags.

The sections found in TBuffer3D (Core/BoundingBox/Raw Sizes/Raw) are sufficient to describe any tessellated shape in a generic fashion. An additional ShapeSpecific section in derived shape specific classes allows a more abstract shape description ("a sphere of inner radius x, outer radius y"). This enables a viewer which knows how to draw (tessellate) the shape itself to do so, which can bring considerable performance and quality benefits, while providing a generic fallback suitable for all viewers.

The rules for client negotiation with the viewer are:

If suitable specialized TBuffer3D class exists, use it, otherwise use TBuffer3D.
Complete the mandatory Core section.
Complete the ShapeSpecific section if applicable.
Complete the BoundingBox if you can.
Pass this buffer to the viewer using one of the AddObject() methods - see below.

If the viewer requires more sections to be completed (Raw/RawSizes) AddObject() will return flags indicating which ones, otherwise it returns kNone. You must fill the buffer and mark these sections valid, and pass the buffer again. A typical code snippet would be:

TBuffer3DSphere sphereBuffer;
// Fill out kCore...
// Fill out kBoundingBox...
// Fill out kShapeSpecific for TBuffer3DSphere
// Try first add to viewer
Int_t reqSections = viewer-&gt;AddObject(buffer);
if (reqSections != TBuffer3D::kNone) {
  if (reqSections & TBuffer3D::kRawSizes) {
     // Fill out kRawSizes...
  }
  if (reqSections & TBuffer3D::kRaw) {
     // Fill out kRaw...
  }
  // Add second time to viewer - ignore return cannot do more
  viewer-&gt;AddObject(buffer);
  }
}

ShapeSpecific: If the viewer can directly display the buffer without filling of the kRaw/kRawSizes section it will not need to request client side tessellation.

Currently we provide the following various shape specific classes, which the OpenGL viewer can take advantage of (see TBuffer3D.h and TBuffer3DTypes.h)

TBuffer3DSphere - solid, hollow and cut spheres*
TBuffer3DTubeSeg - angle tube segment
TBuffer3DCutTube - angle tube segment with plane cut ends.

OpenGL only supports solid spheres at present - cut/hollow ones will be requested tessellated.

Anyone is free to add new TBuffer3D classes, but it should be clear that the viewers require updating to be able to take advantage of them. The number of native shapes in OpenGL will be expanded over time.

BoundingBox: You are not obliged to complete this, as any viewer requiring one internally (OpenGL) will build one for you if you do not provide. However to do this the viewer will force you to provide the raw tessellation, and the resulting box will be axis aligned with the overall scene, which is non-ideal for rotated shapes.

As we need to support orientated (rotated) bounding boxes, TBuffer3D requires the 6 vertices of the box. We also provide a convenience function, SetAABoundingBox(), for simpler case of setting an axis aligned bounding box.

Master/Local Reference Frames

The Core section of TBuffer3D contains two members relating to reference frames: fLocalFrame & fLocalMaster. fLocalFrame indicates if any positions in the buffer (bounding box and tessellation vertexes) are in local or master (world frame). fLocalMaster is a standard 4x4 translation matrix (OpenGL column major ordering) for placing the object into the 3D master frame.

If fLocalFrame is kFALSE, fLocalMaster should contain an identity matrix. This is set by default, and can be reset using SetLocalMasterIdentity() function.

Logical & Physical Objects. There are two cases of object addition:

Add this object as a single independent entity in the world reference frame.
Add a physical placement (copy) of this logical object (described in local reference frame).

The second case is very typical in geometry packages, GEANT4, where we have very large number repeated placements of relatively few logical (unique) shapes. Some viewers (OpenGL only at present) are able to take advantage of this by identifying unique logical shapes from the fID logical ID member of TBuffer3D. If repeated addition of the same fID is found, the shape is cached already - and the costly tessellation does not need to be sent again. The viewer can also perform internal GL specific caching with considerable performance gains in these cases.

For this to work correctly the logical object in must be described in TBuffer3D in the local reference frame, complete with the local/master translation. The viewer indicates this through the interface method

PreferLocalFrame()

If this returns kTRUE you can make repeated calls to AddObject(), with TBuffer3D containing the same fID, and different fLocalMaster placements.

For viewers supporting logical/physical objects, the TBuffer3D content refers to the properties of logical object, with the fLocalMaster transform and the fColor and fTransparency attributes, which can be varied for each physical object.

As a minimum requirement all clients must be capable of filling the raw tessellation of the object buffer, in the master reference frame. Conversely viewers must always be capable of displaying the object described by this buffer.

Scene Rebuilds

It should be understood that AddObject is not an explicit command to the viewer

it may for various reasons decide to ignore it:
It already has the object internally cached .
The object falls outside some 'interest' limits of the viewer camera.
The object is too small to be worth drawing.

In all these cases AddObject() returns kNone, as it does for successful addition, simply indicating it does not require you to provide further information about this object. You should not try to make any assumptions about what the viewer did with it.

This enables the viewer to be connected to a client which sends potentially millions of objects, and only accept those that are of interest at a certain time, caching the relatively small number of CPU/memory costly logical shapes, and retaining/discarding the physical placements as required. The viewer may decide to force the client to rebuild (republish) the scene (via a TPad repaint at present), and thus collect these objects if the internal viewer state changes. It does this presently by forcing a repaint on the attached TPad object - hence the reason for putting all publishing to the viewer in the attached pad objects Paint() method. We will likely remove this requirement in the future, indicating the rebuild request via a normal ROOT signal, which the client can detect.

Physical IDs

TVirtualViewer3D provides for two methods of object addition:virtual Int_t AddObject(const TBuffer3D & buffer, Bool_t * addChildren = 0)

virtual Int_t AddObject(UInt_t physicalID, const TBuffer3D & buffer, Bool_t * addChildren = 0)

If you use the first (simple) case a viewer using logical/physical pairs SetSectionsValid(TBuffer3D::kBoundingBox); will generate IDs for each physical object internally. In the second you can specify a unique identifier from the client, which allows the viewer to be more efficient. It can now cache both logical and physical objects, and only discard physical objects no longer of interest as part of scene rebuilds.

Child Objects

In many geometries there is a rigid containment hierarchy, and so if the viewer is not interested in a certain object due to limits/size then it will also not be interest in any of the contained branch of descendents. Both AddObject() methods have an addChildren parameter. The viewer will complete this (if passed) indicating if children (contained within the one just sent) are worth adding.

Recycling TBuffer3D

Once add AddObject() has been called, the contents are copied to the viewer internally. You are free to destroy this object, or recycle it for the next object if suitable.

Definition at line 19 of file TBuffer3D.h.

Public Types
enum	EBoolOpCode { kCSUnion, kCSIntersection, kCSDifference, kCSNoOp }

enum	ESection { kNone = BIT(0), kCore = BIT(1), kBoundingBox = BIT(2), kShapeSpecific = BIT(3), kRawSizes = BIT(4), kRaw = BIT(5), kAll = kCore\|kBoundingBox\|kShapeSpecific\|kRawSizes\|kRaw }

Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000, kNotDeleted = 0x02000000, kZombie = 0x04000000, kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0), kOverwrite = BIT(1), kWriteDelete = BIT(2) }

enum	EStatusBits { kCanDelete = BIT(0), kMustCleanup = BIT(3), kObjInCanvas = BIT(3), kIsReferenced = BIT(4), kHasUUID = BIT(5), kCannotPick = BIT(6), kNoContextMenu = BIT(8), kInvalidObject = BIT(13) }

Public Member Functions
	TBuffer3D (Int_t type, UInt_t reqPnts=0, UInt_t reqPntsCapacity=0, UInt_t reqSegs=0, UInt_t reqSegsCapacity=0, UInt_t reqPols=0, UInt_t reqPolsCapacity=0)
	Destructor. More...

virtual	~TBuffer3D ()
	Destructor. More...

void	ClearSectionsValid ()
	Clear any sections marked valid. More...

UInt_t	GetSections (UInt_t mask) const

UInt_t	NbPnts () const

UInt_t	NbPols () const

UInt_t	NbSegs () const

Bool_t	SectionsValid (UInt_t mask) const

void	SetAABoundingBox (const Double_t origin[3], const Double_t halfLengths[3])
	Set fBBVertex in kBoundingBox section to a axis aligned (local) BB using supplied origin and box half lengths. More...

void	SetLocalMasterIdentity ()
	Set kRaw tessellation section of buffer with supplied sizes. More...

Bool_t	SetRawSizes (UInt_t reqPnts, UInt_t reqPntsCapacity, UInt_t reqSegs, UInt_t reqSegsCapacity, UInt_t reqPols, UInt_t reqPolsCapacity)
	Set kRaw tessellation section of buffer with supplied sizes. More...

void	SetSectionsValid (UInt_t mask)

Int_t	Type () const

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor. More...

	TObject (const TObject &object)
	TObject copy ctor. More...

virtual	~TObject ()
	TObject destructor. More...

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad. More...

virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action. More...

virtual const char *	ClassName () const
	Returns name of class to which the object belongs. More...

virtual void	Clear (Option_t *="")

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility. More...

virtual Int_t	Compare (const TObject *obj) const
	Compare abstract method. More...

virtual void	Copy (TObject &object) const
	Copy this to obj. More...

virtual void	Delete (Option_t *option="")
	Delete this object. More...

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object. More...

virtual void	Draw (Option_t *option="")
	Default Draw method for all objects. More...

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs. More...

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current pad. More...

virtual void	Dump () const
	Dump contents of object on stdout. More...

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message. More...

virtual void	Execute (const char method, const char params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g. More...

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray. More...

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py). More...

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message. More...

virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes. More...

virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes. More...

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object. More...

virtual const char *	GetIconName () const
	Returns mime type name of object. More...

virtual const char *	GetName () const
	Returns name of object. More...

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py). More...

virtual Option_t *	GetOption () const

virtual const char *	GetTitle () const
	Returns title of object. More...

virtual UInt_t	GetUniqueID () const
	Return the unique object id. More...

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out. More...

virtual ULong_t	Hash () const
	Return hash value for this object. More...

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message. More...

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname". More...

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl. More...

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas. More...

void	InvertBit (UInt_t f)

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory). More...

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...

Bool_t	IsOnHeap () const

virtual Bool_t	IsSortable () const

Bool_t	IsZombie () const

virtual void	ls (Option_t *option="") const
	The ls function lists the contents of a class on stdout. More...

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...

virtual Bool_t	Notify ()
	This method must be overridden to handle object notification. More...

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete. More...

void	operator delete (void *ptr)
	Operator delete. More...

void	operator delete[] (void *ptr)
	Operator delete []. More...

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator. More...

virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself. More...

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list. More...

virtual void	Print (Option_t *option="") const
	This method must be overridden when a class wants to print itself. More...

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory. More...

virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list. More...

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename. More...

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out". More...

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f. More...

void	SetBit (UInt_t f)

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object. More...

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id. More...

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message. More...

Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message. More...

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory. More...

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory. More...

Static Public Member Functions
static UInt_t	DecCSLevel ()
	Decrement CS level. More...

static UInt_t	GetCSLevel ()
	Return CS level. More...

static void	IncCSLevel ()
	Increment CS level. More...

Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag. More...

static Bool_t	GetObjectStat ()
	Get status of object stat flag. More...

static void	SetDtorOnly (void *obj)
	Set destructor only flag. More...

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable. More...

Public Attributes
Double_t	fBBVertex [8][3]

Int_t	fColor

TObject *	fID

Bool_t	fLocalFrame

Double_t	fLocalMaster [16]

UInt_t	fPhysicalID

Double_t *	fPnts

Int_t *	fPols

Bool_t	fReflection

Int_t *	fSegs

Short_t	fTransparency

Private Member Functions
	TBuffer3D (const TBuffer3D &)

void	Init ()
	Initialise buffer. More...

const TBuffer3D &	operator= (const TBuffer3D &)

Private Attributes
UInt_t	fNbPnts

UInt_t	fNbPols

UInt_t	fNbSegs

UInt_t	fPntsCapacity

UInt_t	fPolsCapacity

UInt_t	fSections

UInt_t	fSegsCapacity

const Int_t	fType

Static Private Attributes
static UInt_t	fgCSLevel = 0

Additional Inherited Members
Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected). More...

void	MakeZombie ()

#include <TBuffer3D.h>

Inheritance diagram for TBuffer3D:

[legend]

Member Enumeration Documentation

enum TBuffer3D::EBoolOpCode

Enumerator
kCSUnion
kCSIntersection
kCSDifference
kCSNoOp

Definition at line 45 of file TBuffer3D.h.

enum TBuffer3D::ESection

Enumerator
kNone
kCore
kBoundingBox
kShapeSpecific
kRawSizes
kRaw
kAll

Definition at line 51 of file TBuffer3D.h.

Constructor & Destructor Documentation

TBuffer3D::TBuffer3D ( const TBuffer3D & )

private

TBuffer3D::TBuffer3D	(	Int_t	type,
		UInt_t	reqPnts = `0`,
		UInt_t	reqPntsCapacity = `0`,
		UInt_t	reqSegs = `0`,
		UInt_t	reqSegsCapacity = `0`,
		UInt_t	reqPols = `0`,
		UInt_t	reqPolsCapacity = `0`
	)

Destructor.

Construct from supplied shape type and raw sizes

Definition at line 222 of file TBuffer3D.cxx.

TBuffer3D::~TBuffer3D ( )

virtual

Destructor.

Definition at line 235 of file TBuffer3D.cxx.

Member Function Documentation

void TBuffer3D::ClearSectionsValid ( )

Clear any sections marked valid.

Definition at line 286 of file TBuffer3D.cxx.

UInt_t TBuffer3D::DecCSLevel ( )

static

Decrement CS level.

Definition at line 512 of file TBuffer3D.cxx.

UInt_t TBuffer3D::GetCSLevel ( )

static

Return CS level.

Definition at line 496 of file TBuffer3D.cxx.

UInt_t TBuffer3D::GetSections ( UInt_t mask ) const

inline

Definition at line 70 of file TBuffer3D.h.

void TBuffer3D::IncCSLevel ( )

static

Increment CS level.

Definition at line 504 of file TBuffer3D.cxx.

void TBuffer3D::Init ( )

private

Initialise buffer.

Definition at line 245 of file TBuffer3D.cxx.

UInt_t TBuffer3D::NbPnts ( ) const

inline

Definition at line 82 of file TBuffer3D.h.

UInt_t TBuffer3D::NbPols ( ) const

inline

Definition at line 84 of file TBuffer3D.h.

UInt_t TBuffer3D::NbSegs ( ) const

inline

Definition at line 83 of file TBuffer3D.h.

const TBuffer3D& TBuffer3D::operator= ( const TBuffer3D & )

private

Bool_t TBuffer3D::SectionsValid ( UInt_t mask ) const

inline

Definition at line 69 of file TBuffer3D.h.

void TBuffer3D::SetAABoundingBox	(	const Double_t	origin[3],
		const Double_t	halfLengths[3]
	)

Set fBBVertex in kBoundingBox section to a axis aligned (local) BB using supplied origin and box half lengths.

  7-------6
 /|      /|
3-------2 |
| 4-----|-5
|/      |/
0-------1

Definition at line 320 of file TBuffer3D.cxx.

void TBuffer3D::SetLocalMasterIdentity ( )

Set kRaw tessellation section of buffer with supplied sizes.

Set fLocalMaster in section kCore to identity

Definition at line 296 of file TBuffer3D.cxx.

Bool_t TBuffer3D::SetRawSizes	(	UInt_t	reqPnts,
		UInt_t	reqPntsCapacity,
		UInt_t	reqSegs,
		UInt_t	reqSegsCapacity,
		UInt_t	reqPols,
		UInt_t	reqPolsCapacity
	)

Set kRaw tessellation section of buffer with supplied sizes.

Definition at line 359 of file TBuffer3D.cxx.

void TBuffer3D::SetSectionsValid ( UInt_t mask )

inline

Definition at line 67 of file TBuffer3D.h.

Int_t TBuffer3D::Type ( ) const

inline

Definition at line 87 of file TBuffer3D.h.

Member Data Documentation

Double_t TBuffer3D::fBBVertex[8][3]

Definition at line 109 of file TBuffer3D.h.

Int_t TBuffer3D::fColor

Definition at line 90 of file TBuffer3D.h.

UInt_t TBuffer3D::fgCSLevel = 0

staticprivate

Definition at line 41 of file TBuffer3D.h.

TObject* TBuffer3D::fID

Definition at line 89 of file TBuffer3D.h.

Bool_t TBuffer3D::fLocalFrame

Definition at line 92 of file TBuffer3D.h.

Double_t TBuffer3D::fLocalMaster[16]

Definition at line 94 of file TBuffer3D.h.

UInt_t TBuffer3D::fNbPnts

private

Definition at line 24 of file TBuffer3D.h.

UInt_t TBuffer3D::fNbPols

private

Definition at line 26 of file TBuffer3D.h.

UInt_t TBuffer3D::fNbSegs

private

Definition at line 25 of file TBuffer3D.h.

UInt_t TBuffer3D::fPhysicalID

mutable

Definition at line 120 of file TBuffer3D.h.

Double_t* TBuffer3D::fPnts

Definition at line 114 of file TBuffer3D.h.

UInt_t TBuffer3D::fPntsCapacity

private

Definition at line 28 of file TBuffer3D.h.

Int_t* TBuffer3D::fPols

Definition at line 116 of file TBuffer3D.h.

UInt_t TBuffer3D::fPolsCapacity

private

Definition at line 30 of file TBuffer3D.h.

Bool_t TBuffer3D::fReflection

Definition at line 93 of file TBuffer3D.h.

UInt_t TBuffer3D::fSections

private

Definition at line 32 of file TBuffer3D.h.

Int_t* TBuffer3D::fSegs

Definition at line 115 of file TBuffer3D.h.

UInt_t TBuffer3D::fSegsCapacity

private

Definition at line 29 of file TBuffer3D.h.

Short_t TBuffer3D::fTransparency

Definition at line 91 of file TBuffer3D.h.

const Int_t TBuffer3D::fType

private

Definition at line 22 of file TBuffer3D.h.

The documentation for this class was generated from the following files:

core/base/inc/TBuffer3D.h
core/base/src/TBuffer3D.cxx

Filling TBuffer3D and Adding to Viewer

Master/Local Reference Frames

Scene Rebuilds

Physical IDs

Child Objects

Recycling TBuffer3D

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Private Member Functions

Private Attributes

Static Private Attributes

Additional Inherited Members

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation