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