computeScreenSpaceError

[listenheart]

I think this change is better

double ThreeDTileNode::computeScreenSpaceError(osgUtil::CullVisitor* cv)
{
    double distance = osg::maximum(getDistanceToTile(cv), 0.0000001);
    const osg::Matrix& proj = cv->getCurrentCamera()->getProjectionMatrix();
    if (proj(3,3)==0.0) // perspective
    {
        double height = cv->getCurrentCamera()->getViewport()->height();
        return (*_tile->geometricError() * height) / (distance * _tileset->getSSEDenominator());
    }
    else // orthographic
    {
        const osg::Viewport* vp = cv->getCurrentCamera()->getViewport();
        double L, R, B, T, N, F;
        proj.getOrtho(L, R, B, T, N, F);
        double pixelSize = osg::maximum(T-B, R-L) / osg::maximum(vp->width(), vp->height());
        return (*_tile->geometricError()) / pixelSize;
    }
}

I have a bug when using RTT ，I changed this code

double ThreeDTileNode::computeScreenSpaceError(osgUtil::CullVisitor* cv)
{
   return cv->clampedPixelSize(_localBoundingSphere.center(),*_tile->geometricError()*0.5);
}

[jasonbeverage]

I'm hesitant to change that code as it works exactly like Cesium does. What is the bug you're getting with an RTT camera?

[listenheart]

Yes, use Rtt camera to output images. Orthographic projection is no problem, but perspective projection has a bug, and it outputs a blank image.
OSG's clampedPixelSize is similar to Cesium's. Both calculate the OpenGL world coordinate length to the screen pixel length.