12226e4371
and passed as paramters into straight forward non const built in types, i.e. const bool foogbar(const int) becomes bool foobar(int).
107 lines
4.2 KiB
Plaintext
107 lines
4.2 KiB
Plaintext
//C++ header - Open Scene Graph - Copyright (C) 1998-2002 Robert Osfield
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//Distributed under the terms of the GNU Library General Public License (LGPL)
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//as published by the Free Software Foundation.
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#ifndef OSG_IMPOSTOR
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#define OSG_IMPOSTOR 1
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#include <osg/LOD>
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#include <osg/ImpostorSprite>
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namespace osg {
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/** Impostor - is a form of Level Of Detail group node which allows both switching
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* between children depending on distance from eye point and image caching.
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*
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* The principle behind Imposters is that they cache an image of real geometry and then the image is drawn
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* in subsequent frames instead of the real geometry. Its a bit like a
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* Billboard *but* is updated at runtime and w.r.t view point. By drawing
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* just the texture mapped quad you can cut down scene complexity and
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* improve performance.
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*
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* For more details have a look at:
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*
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* http://grail.cs.washington.edu/projects/hic/
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*
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* The OSG doesn't implement exactly the same technique as above, but its
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* should be a good starting place. The OSG's impostors are much less
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* intrusive since you don't need to restructure your whole scene to use
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* them.
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*
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* All you need to do to use Impostors is to set up the visible
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* range values for each LOD child of the Impostor, as per osg::LOD,
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* and set an Impostor threshold to tell the renderer at what distance
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* the Impostor's image caching should cut in. The osg::CullVisitor
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* automatically handles all the setting of pre-rendering stages to
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* calculate the required ImpostorSprites (which encapsulates the image
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* cache and quad), and updates them as the view point changes. If you
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* use osg::SceneView/CullVisitor all the complexity of supporting
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* Impostor will be nicely hidden away.
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*
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* TODO:
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* Various improvements are planned for the Impostor-
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* 1) Estimation of how many frames an ImpostorSprite will be reused, if
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* it won't be used more often than a minimum threshold then do not create
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* ImpostorSprite - use the real geometry.
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* 2) Sharing of texture memory between ImpostorSprites.
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* 3) Simple 3D geometry for ImpostorSprite's rather than Billboarding.
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* 4) Shrinking of the ImpostorSprite size to more closely fit the underlying
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* geometry.
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*/
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class SG_EXPORT Impostor : public LOD
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{
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public :
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Impostor();
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Impostor(const Impostor& es, const CopyOp& copyop=CopyOp::SHALLOW_COPY):
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LOD(es,copyop),
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_impostorSpriteList(),
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_impostorThreshold(es._impostorThreshold) {}
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META_Node(osg, Impostor);
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typedef std::vector< ref_ptr<ImpostorSprite> > ImpostorSpriteList;
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/** Set the Impostor threshold distance.
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* For eye points further than this threshold the Imposter is used if appropriate,
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* otherwise the LOD children as chosen as per a standard LOD node.*/
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inline void setImpostorThreshold(float distance) { _impostorThreshold = distance; }
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/** Set the Impostor threshold distance relative to the node's bounding
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* sphere's radius.*/
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inline void setImpostorThresholdToBound(float ratio=1.0f) { _impostorThreshold = getBound().radius()*ratio; }
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/* Get the Impostor threshold distance.*/
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inline float getImpostorThreshold() const { return _impostorThreshold; }
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/* Get the Impostor threshold distance squared.*/
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inline float getImpostorThreshold2() const { return _impostorThreshold*_impostorThreshold; }
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/** Find the ImposterSprite which fits the current eye point best.*/
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ImpostorSprite* findBestImpostorSprite(const osg::Vec3& currLocalEyePoint);
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/** Add an ImpostorSprite to the Impostor.*/
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void addImpostorSprite(ImpostorSprite* is);
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/** Get the list of ImpostorSprites attached to this Impostor.*/
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inline ImpostorSpriteList& getImpostorSpriteList() { return _impostorSpriteList; }
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/** Get a const list of ImpostorSprites attached to this const Impostor.*/
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inline const ImpostorSpriteList& getImpostorSpriteList() const { return _impostorSpriteList; }
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protected :
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virtual ~Impostor() {}
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virtual bool computeBound() const;
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ImpostorSpriteList _impostorSpriteList;
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float _impostorThreshold;
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};
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}
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#endif
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