DynamicLODScaleCallback Struct Reference

List of all members.

Public Member Functions
	DynamicLODScaleCallback (float fallOff)
void	operator() (osg::Node *node, osg::NodeVisitor *nv)
Public Attributes
float	_fallOff

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Detailed Description

Cull callback that dynamically computes an LOD scale based on distance to the camera and a "fall off" metric. As the fall off increases, farther objects' LOD scale will increase. A good range for the fall-off number is 0..5.

Definition at line 32 of file DynamicLODScaleCallback.

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Constructor & Destructor Documentation

DynamicLODScaleCallback::DynamicLODScaleCallback

(

float

fallOff

)

[inline]

Definition at line 34 of file DynamicLODScaleCallback.

: _fallOff(fallOff) { }

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Member Function Documentation

void DynamicLODScaleCallback::operator()	(	osg::Node *	node,
		osg::NodeVisitor *	nv
	)		[inline]

Definition at line 36 of file DynamicLODScaleCallback.

    {
        osg::CullStack* cs = dynamic_cast<osg::CullStack*>(nv);
        if ( cs )
        {
            osg::LOD* lod = static_cast<osg::LOD*>( node );
            osg::Vec3 center = lod->getCenter(); 

            osg::Vec3 eye = nv->getEyePoint();
            osg::Vec3 eyeVec = eye; eyeVec.normalize();
            float has = osg::clampAbove( eye.length() - 6356752.3142f, 0.0f );
            float centerToEye = nv->getDistanceToViewPoint(center, false);
            float bsToEye = centerToEye - lod->getChild(0)->getBound().radius();

            float scaleAdj = 1.0f;
            if ( bsToEye > has )
            {
                float denom = osg::maximum(0.1f, (1.0f/_fallOff)) * 10000.0f;
                scaleAdj = osg::clampBetween( log10f(bsToEye/denom), 1.0f, 3.0f );
                
                //OE_INFO << LC 
                //    << std::fixed
                //    << "centerToEye=" << centerToEye 
                //    << ", bsToEye=" << bsToEye
                //    << ", scaleAdj=" << scaleAdj
                //    << std::endl;
            }

            float lodScale = cs->getLODScale();
            cs->setLODScale( lodScale * scaleAdj );
            traverse( node, nv );
            cs->setLODScale( lodScale );
        }
        else
        {
            traverse( node, nv );
        }
    }

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Member Data Documentation

float DynamicLODScaleCallback::_fallOff

Definition at line 75 of file DynamicLODScaleCallback.

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The documentation for this struct was generated from the following file:

• /home/cube/sources/osgearth/src/osgEarthDrivers/engine_osgterrain/DynamicLODScaleCallback