110 lines
4.2 KiB
Plaintext
110 lines
4.2 KiB
Plaintext
//C++ header - Open Scene Graph - Copyright (C) 1998-2001 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_LOD
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#define OSG_LOD 1
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#include <osg/Group>
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namespace osg {
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/** LOD - Level Of Detail group node which allows switching between children
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depending on distance from eye point.
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Typical uses are for load balancing - objects further away from
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the eye point are rendered at a lower level of detail, and at times
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of high stress on the graphics pipeline lower levels of detail can
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also be chosen.
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The children are ordered from most detailed (for close up views) to the least
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(see from a distance), and a set of ranges are used to decide which LOD is used
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at different view distances, the criteria used is child 'i' is used when
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range[i]<dist<range[i+1] is true. This requires there to be n+1 range values where the number of
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children is n, since no maximum distance of infinity is assumed. If the number of range values (m)
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is insufficient then the children m through to n will be ignored, only 0..m-1 will be used
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during rendering.
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*/
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class SG_EXPORT LOD : public Group
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{
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public :
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LOD() {}
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/** Copy constructor using CopyOp to manage deep vs shallow copy.*/
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LOD(const LOD&,const CopyOp& copyop=CopyOp::SHALLOW_COPY);
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META_Node(LOD);
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virtual void traverse(NodeVisitor& nv);
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/** Sets the value of range list element index to range which
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is a floating point distance specified in world coordinates.
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Range list automatically expands to accommodate values beyond
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the current getNumRanges().*/
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void setRange(const unsigned int index, const float range);
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/** returns the range for specified index.*/
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inline const float getRange(const unsigned int index) const { return _rangeList[index]; }
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/** returns the number of ranges currently set.*/
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inline const int getNumRanges() const { return _rangeList.size(); }
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/** Sets the object-space point which defines the center of the osg::LOD.
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center is affected by any transforms in the hierarchy above the osg::LOD.*/
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inline void setCenter(const Vec3 ¢er) { _center = center; }
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/** return the LOD center point. */
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inline const Vec3& getCenter() const { return _center; }
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/** Callback attached to an LOD which allows the users to customize the selection of LOD children.*/
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struct EvaluateLODCallback : public osg::Referenced
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{
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/** Compute the child to select.*/
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virtual const int evaluateLODChild(const osg::LOD* lod, const Vec3& eye_local, const float bias) const;
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};
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friend struct osg::LOD::EvaluateLODCallback;
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/** Set the EvaluateLODCallback which allows users to attach customize computation of the the selection of LOD children.*/
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void setEvaluateLODCallback(EvaluateLODCallback* cbc) { _evaluateLODCallback=cbc; }
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/** Get the non const ComputeBillboardCallback.*/
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EvaluateLODCallback* getEvaluateLODCallback() { return _evaluateLODCallback.get(); }
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/** Get the const ComputeBillboardCallback.*/
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const EvaluateLODCallback* getEvaluateLODCallback() const { return _evaluateLODCallback.get(); }
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/** return the child to traverse.
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Selected by the distance between the eye point in local
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coordinates and the LOD center, multiplied by the bias.*/
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inline const int evaluate(const Vec3& eye_local,const float bias=1.0f) const
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{
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if (_evaluateLODCallback.valid())
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return _evaluateLODCallback->evaluateLODChild(this,eye_local,bias);
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else
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return evaluateLODChild(eye_local,bias);
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}
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protected :
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virtual ~LOD() {}
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virtual const int evaluateLODChild(const Vec3& eye_local,const float bias) const;
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typedef std::vector<float> RangeList;
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RangeList _rangeList;
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RangeList _rangeList2;
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ref_ptr<EvaluateLODCallback> _evaluateLODCallback;
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Vec3 _center;
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};
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}
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#endif
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