TGLScene

 Construct scene object

 Purge out the DL cache - when per drawable DL purging implemented
 this no longer really required. However should be faster....

 Adopt dynamically created logical 'shape' - add to internal map and take
 responsibility for deleting

 Zero ID logical shapes are not unique - this simple means the external object
 does not exist - should never be asked to destroy these singularly

 Destroy all logical shapes in scene
 Return count of number destroyed

 Zero ID logical shapes are not unique - this simple means the external object
 does not exist - should never be asked to seach for this

 Adopt dynamically created physical 'shape' - add to internal map and take
 responsibility for deleting

 Destroy physical shape defined by unique 'ID'
 Returns kTRUE if found/destroyed - kFALSE otherwise

 Destroy all logical shapes in scene
 Return count of number destroyed

 Find and return physical shape identified by unqiue 'ID'
 Returns 0 if not found

 Moves logicals to refresh-cache.

 Wipes logicals in refresh-cache.

 Find and return logical shape identified by unqiue 'ID' in refresh-cache.
 Returns 0 if not found.

 Draw out scene into current GL context, using passed arguments:

 'camera' - used for for object culling, manip scalling
 'sceneFlags'  - draw flags for scene - see TGLDrawFlags
 'timeout'- timeout for scene draw (in milliseconds) - if 0.0 unlimited
 'axesType' - axis style - one of TGLViewer::EAxesType
 'reference' - position of reference marker (or none if null)
 'forSelect' - is draw for select? If kTRUE clip and manip objects (which
            cannot be selected) are not drawn

 Perform a internal draw pass - multiple passes are required for some
 clip shapes

 Sort the TGLPhysical draw list by shape bounding box volume, from
 large to small. This makes dropout of shapes with time limited
 Draw() calls must less noticable. As this does not use projected
 size it only needs to be done after a scene content change - not
 everytime scene drawn (potential camera/projection change).

 Compare 'shape1' and 'shape2' bounding box volumes - return kTRUE if
 'shape1' bigger than 'shape2'

 Draw out scene guides - axes and reference marker

 'camera'    - current active camera - required for calculating projection size
 'axesType'  - kAxesNone, kAxesOrigin (run through origin), kAxesEdge (at scene box edge)
 'reference' - if not null, draw orange reference sphere at vertex

 Draw out number (as string) 'num', centered on vertex 'center'

 Perform select draw using arguments:

 'camera' - used for for object culling
 'style'  - draw style kFill (filled polygons) kOutline (polygons + outlines)
            kWireFrame

 Arguments are passed on to Draw(), with unlimted time

 Returns kTRUE if selected object is different then currently selected
 fSelectedPhysical. The result is stored in fSelectionResult member.
 One still has to call ApplySelection() to activate this change.

 If secondary-selection is activated (by calling
 ActivateSecSelect() prior requesting the selection another
 selection pass is done on selected object if it supports
 secondary selection. The secondary select records are then available in:
 fTriedSecSelect, fNSecHits, fSelectBuffer and fSortedHits.

 Makes result of last selection (fSelectionResult) the currently
 selected object (fSelectedPhysical).

 Set full color attributes on current selected physical shape:

 0...3  - diffuse
 4...7  - ambient
 8...11 - specular
 12..15 - emission
 16     - shininess

 see OpenGL documentation for details of materials

 Set full color attributes on all physical shapes sharing the same
 logical shape as the selected physical

 0...3  - diffuse
 4...7  - ambient
 8...11 - specular
 12..15 - emission
 16     - shininess

 see OpenGL documentation for details of materials

 Update geometry of the selected physical. 'trans' and 'scale' specify the
 translation and scaling components of the physical shapes translation matrix
 See TGLMatrix for more details

 Setup clipping objects for current scene bounding box

 Clear out exising clipping objects

 Get state of clip object 'type' into data vector:

 'type' requested        'data' contents returned
 kClipPlane              4 components - A,B,C,D - of plane eq : Ax+By+CZ+D = 0
 kBoxPlane               6 components - Box Center X/Y/Z - Box Extents X/Y/Z

 Set state of clip object 'type' into data vector:

 'type' specified        'data' contents interpretation
 kClipNone               ignored
 kClipPlane              4 components - A,B,C,D - of plane eq : Ax+By+CZ+D = 0
 kBoxPlane               6 components - Box Center X/Y/Z - Box Extents X/Y/Z

 Get current type active in viewer - returns one of kClipNone
 kClipPlane or kClipBox

 Set current clip active in viewer - 'type' is one of kClipNone
 kClipPlane or kClipBox. 'edit' indicates if clip object should
 been shown/edited directly in viewer (current manipulator attached to it)
 kTRUE if so (ignored for kClipNone), kFALSE otherwise

 Update (if required) and return the scene bounding box
 Encapsulates all physical shapes bounding box with axes aligned box

 Output simple scene stats to std::cout

 Return memory cost of scene
 Warning: NOT CORRECT at present - doesn't correctly calculate size
 of logical shapes with dynamic internal contents

 Reset internal draw stats

 Update draw stats, for newly drawn 'shape'

 Output draw stats to std::cout

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 Test if lock is a valid type to take/release
 kUnlocked is never valid in these cases

 Non-copyable class

 Selected Object

 Viewport/camera screen markup