269 lines
12 KiB
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269 lines
12 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<TITLE>class SG_EXPORT osg::Impostor</TITLE>
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<META NAME="GENERATOR" CONTENT="DOC++ 3.4.8">
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<H2>class SG_EXPORT <A HREF="#DOC.DOCU">osg::Impostor</A></H2></H2><BLOCKQUOTE>Impostor - is a form of Level Of Detail group node which allows both switching between children depending on distance from eye point and image caching.</BLOCKQUOTE>
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<HR>
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<H2>Inheritance:</H2>
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<APPLET CODE="ClassGraph.class" WIDTH=600 HEIGHT=125>
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<param name=classes value="MNode,M,CGroup,MGroup.html,CLOD,MLOD.html,CImpostor,MImpostor.html">
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<param name=before value="M,M,M,M">
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<param name=after value="Md_SPSP,Md_SP,Md_,M">
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<param name=indent value="0,1,2,3">
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<param name=arrowdir value="down">
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</APPLET>
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<HR>
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<DL>
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<P><DL>
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<DT><H3>Public Methods</H3><DD><DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif> <B><A HREF="#DOC.2.46.1">Impostor</A></B>()
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif> <B><A HREF="#DOC.2.46.2">Impostor</A></B>(const <!1><A HREF="Impostor.html#DOC.2.46.2">Impostor</A>& es, const <!1><A HREF="CopyOp.html">CopyOp</A>& copyop=CopyOp::SHALLOW_COPY)
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif> <B><A HREF="#DOC.2.46.3">META_Node</A></B>(<!1><A HREF="Impostor.html">Impostor</A>)
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline void <B><A HREF="#DOC.2.46.4">setImpostorThreshold</A></B>(float <!1><A HREF="Plane.html#DOC.2.75.21">distance</A>)
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<DD><I>Set the Impostor threshold distance.</I>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline void <B><A HREF="#DOC.2.46.5">setImpostorThresholdToBound</A></B>(float ratio=1.0f)
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<DD><I>Set the Impostor threshold distance relative to the node's bounding sphere's radius</I>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline const float <B><A HREF="#DOC.2.46.6">getImpostorThreshold</A></B>() const
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline const float <B><A HREF="#DOC.2.46.7">getImpostorThreshold2</A></B>() const
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif><!1><A HREF="ImpostorSprite.html">ImpostorSprite</A>* <B><A HREF="#DOC.2.46.8">findBestImpostorSprite</A></B>(const <!1><A HREF="Vec3.html">osg::Vec3</A>& currLocalEyePoint)
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<DD><I>Find the ImposterSprite which fits the current eye point best</I>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>void <B><A HREF="#DOC.2.46.9">addImpostorSprite</A></B>(<!1><A HREF="ImpostorSprite.html">ImpostorSprite</A>* is)
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<DD><I>Add an ImpostorSprite to the Impostor</I>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline ImpostorSpriteList& <B><A HREF="#DOC.2.46.10">getImpostorSpriteList</A></B>()
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<DD><I>Get the list of ImpostorSprites attached to this Impostor</I>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>inline const ImpostorSpriteList& <B><A HREF="#DOC.2.46.11">getImpostorSpriteList</A></B>() const
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<DD><I>Get a const list of ImpostorSprites attached to this const Impostor</I>
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</DL></P>
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<P><DL>
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<DT><H3>Protected Fields</H3><DD><DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>ImpostorSpriteList <B><A HREF="#DOC.2.46.14">_impostorSpriteList</A></B>
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>float <B><A HREF="#DOC.2.46.15">_impostorThreshold</A></B>
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</DL></P>
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<P><DL>
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<DT><H3>Protected Methods</H3><DD><DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>virtual <B><A HREF="#DOC.2.46.12">~Impostor</A></B>()
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<DT>
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<IMG ALT="[more]" BORDER=0 SRC=icon1.gif>virtual const bool <B><A HREF="#DOC.2.46.13">computeBound</A></B>() const
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</DL></P>
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</DL>
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<HR><H3>Inherited from <A HREF="LOD.html">LOD</A>:</H3>
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<DL>
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<P><DL>
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<DT><H3>Public Methods</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>virtual void <B>traverse</B>(<!1><A HREF="NodeVisitor.html">NodeVisitor</A>& nv)
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<DT>
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<IMG ALT="o" SRC=icon2.gif>void <B>setRange</B>(const unsigned int index, const float range)
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const float <B>getRange</B>(const unsigned int index) const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const unsigned int <B>getNumRanges</B>() const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline void <B>setCenter</B>(const <!1><A HREF="Vec3.html">Vec3</A> &<!1><A HREF="BoundingSphere.html#DOC.2.5.8">center</A>)
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const <!1><A HREF="Vec3.html">Vec3</A>& <B>getCenter</B>() const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>void <B>setEvaluateLODCallback</B>(<!1><A HREF="LOD.html#DOC.2.55.10">EvaluateLODCallback</A>* cbc)
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<DT>
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<IMG ALT="o" SRC=icon2.gif><!1><A HREF="LOD.html#DOC.2.55.10">EvaluateLODCallback</A>* <B>getEvaluateLODCallback</B>()
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<DT>
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<IMG ALT="o" SRC=icon2.gif>const <!1><A HREF="LOD.html#DOC.2.55.10">EvaluateLODCallback</A>* <B>getEvaluateLODCallback</B>() const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const int <B>evaluate</B>(const <!1><A HREF="Vec3.html">Vec3</A>& eye_local, const float bias=1.0f) const
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</DL></P>
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<P><DL>
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<DT><H3>Public Members</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>struct <B>EvaluateLODCallback</B>: public <!1><A HREF="Referenced.html">osg::Referenced</A>
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</DL></P>
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<P><DL>
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<DT><H3>Protected Fields</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>RangeList <B>_rangeList2</B>
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<DT>
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<IMG ALT="o" SRC=icon2.gif><!1><A HREF="ref_ptr.html">ref_ptr</A><<!1><A HREF="LOD.html#DOC.2.55.10">EvaluateLODCallback</A>> <B>_evaluateLODCallback</B>
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<DT>
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<IMG ALT="o" SRC=icon2.gif><!1><A HREF="Vec3.html">Vec3</A> <B>_center</B>
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</DL></P>
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<P><DL>
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<DT><H3>Protected Methods</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>virtual const int <B>evaluateLODChild</B>(const <!1><A HREF="Vec3.html">Vec3</A>& eye_local, const float bias) const
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</DL></P>
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<P><DL>
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<DT><H3>Protected Members</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>typedef std::vector<float> RangeList RangeList <B>_rangeList</B>
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</DL></P>
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</DL>
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<HR><H3>Inherited from <A HREF="Group.html">Group</A>:</H3>
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<DL>
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<P><DL>
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<DT><H3>Public Methods</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>virtual bool <B>addChild</B>( Node* child )
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<DT>
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<IMG ALT="o" SRC=icon2.gif>virtual bool <B>removeChild</B>( Node* child )
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<DT>
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<IMG ALT="o" SRC=icon2.gif>virtual bool <B>replaceChild</B>( Node* origChild, Node* newChild )
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const unsigned int <B>getNumChildren</B>() const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline Node* <B>getChild</B>( const unsigned int i )
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline const Node* <B>getChild</B>( const unsigned int i ) const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline bool <B>containsNode</B>( const Node* node ) const
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline ChildList::iterator <B>findNode</B>( const Node* node )
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<DT>
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<IMG ALT="o" SRC=icon2.gif>inline ChildList::const_iterator <B>findNode</B>( const Node* node ) const
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</DL></P>
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<P><DL>
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<DT><H3>Protected Fields</H3><DD><DT>
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<IMG ALT="o" SRC=icon2.gif>ChildList <B>_children</B>
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</DL></P>
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</DL>
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<A NAME="DOC.DOCU"></A>
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<HR>
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<H2>Documentation</H2>
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<BLOCKQUOTE>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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<P>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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<P>For more details have a look at:
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<P>http://grail.cs.washington.edu/projects/hic/
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<P>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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<P>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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<P>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.</BLOCKQUOTE>
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<DL>
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<A NAME="Impostor"></A>
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<A NAME="DOC.2.46.1"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B> Impostor()</B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="Impostor"></A>
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<A NAME="DOC.2.46.2"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B> Impostor(const <!1><A HREF="Impostor.html#DOC.2.46.2">Impostor</A>& es, const <!1><A HREF="CopyOp.html">CopyOp</A>& copyop=CopyOp::SHALLOW_COPY)</B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="META_Node"></A>
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<A NAME="DOC.2.46.3"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B> META_Node(<!1><A HREF="Impostor.html">Impostor</A>)</B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="setImpostorThreshold"></A>
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<A NAME="DOC.2.46.4"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline void setImpostorThreshold(float <!1><A HREF="Plane.html#DOC.2.75.21">distance</A>)</B></TT>
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<DD>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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<DL><DT><DD></DL><P>
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<A NAME="setImpostorThresholdToBound"></A>
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<A NAME="DOC.2.46.5"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline void setImpostorThresholdToBound(float ratio=1.0f)</B></TT>
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<DD>Set the Impostor threshold distance relative to the node's bounding
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sphere's radius
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<DL><DT><DD></DL><P>
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<A NAME="getImpostorThreshold"></A>
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<A NAME="DOC.2.46.6"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline const float getImpostorThreshold() const </B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="getImpostorThreshold2"></A>
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<A NAME="DOC.2.46.7"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline const float getImpostorThreshold2() const </B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="findBestImpostorSprite"></A>
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<A NAME="DOC.2.46.8"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B><!1><A HREF="ImpostorSprite.html">ImpostorSprite</A>* findBestImpostorSprite(const <!1><A HREF="Vec3.html">osg::Vec3</A>& currLocalEyePoint)</B></TT>
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<DD>Find the ImposterSprite which fits the current eye point best
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<DL><DT><DD></DL><P>
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<A NAME="addImpostorSprite"></A>
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<A NAME="DOC.2.46.9"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>void addImpostorSprite(<!1><A HREF="ImpostorSprite.html">ImpostorSprite</A>* is)</B></TT>
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<DD>Add an ImpostorSprite to the Impostor
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<DL><DT><DD></DL><P>
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<A NAME="getImpostorSpriteList"></A>
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<A NAME="DOC.2.46.10"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline ImpostorSpriteList& getImpostorSpriteList()</B></TT>
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<DD>Get the list of ImpostorSprites attached to this Impostor
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<DL><DT><DD></DL><P>
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<A NAME="getImpostorSpriteList"></A>
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<A NAME="DOC.2.46.11"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>inline const ImpostorSpriteList& getImpostorSpriteList() const </B></TT>
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<DD>Get a const list of ImpostorSprites attached to this const Impostor
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<DL><DT><DD></DL><P>
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<A NAME="~Impostor"></A>
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<A NAME="DOC.2.46.12"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>virtual ~Impostor()</B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="computeBound"></A>
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<A NAME="DOC.2.46.13"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>virtual const bool computeBound() const </B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="_impostorSpriteList"></A>
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<A NAME="DOC.2.46.14"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>ImpostorSpriteList _impostorSpriteList</B></TT>
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<DL><DT><DD></DL><P>
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<A NAME="_impostorThreshold"></A>
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<A NAME="DOC.2.46.15"></A>
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<DT><IMG ALT="o" BORDER=0 SRC=icon2.gif><TT><B>float _impostorThreshold</B></TT>
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<DL><DT><DD></DL><P></DL>
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<HR><DL><DT><B>This class has no child classes.</B></DL>
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<DL><DT><DD></DL><P><P><I><A HREF="index.html">Alphabetic index</A></I> <I><A HREF="HIER.html">HTML hierarchy of classes</A> or <A HREF="HIERjava.html">Java</A></I></P><HR>
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<BR>
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