OpenSceneGraph/src/osg/Billboard.cpp

#include <stdio.h>
#include <math.h>

#include <osg/Billboard>

using namespace osg;

#define square(x)   ((x)*(x))

Billboard::Billboard()
{
    _mode = AXIAL_ROT;
    //    _mode = POINT_ROT_WORLD;
    _axis.set(0.0f,0.0f,1.0f);
}


Billboard::~Billboard()
{
}


const bool Billboard::addDrawable(Drawable *gset)
{
    if (Geode::addDrawable(gset))
    {
        Vec3 pos(0.0f,0.0f,0.0f);
        while (_positionList.size()<_drawables.size())
        {
            _positionList.push_back(pos);
        }
        return true;
    }
    return false;
}


const bool Billboard::addDrawable(Drawable *gset,const Vec3& pos)
{
    if (Geode::addDrawable(gset))
    {
        while (_positionList.size()<_drawables.size())
        {
            _positionList.push_back(pos);
        }
        return true;
    }
    return false;
}


const bool Billboard::removeDrawable( Drawable *gset )
{
    PositionList::iterator pitr = _positionList.begin();
    for (DrawableList::iterator itr=_drawables.begin();
        itr!=_drawables.end();
        ++itr,++pitr)
    {
        if (itr->get()==gset)
        {
            // note ref_ptr<> automatically handles decrementing gset's reference count.
            _drawables.erase(itr);
            _positionList.erase(pitr);
            _bsphere_computed = false;
            return true;
        }
    }
    return false;
}


void Billboard::calcRotation(const Vec3& eye_local, const Vec3& pos_local,Matrix& mat) const 
{
    switch(_mode)
    {
        case(AXIAL_ROT):
        {
            // note currently assumes that axis is (0,0,1) for speed of
            // executation and implementation.  This will be rewritten
            // on second pass of Billboard. Robert Osfield Jan 2001.
            Vec3 ev = pos_local-eye_local;
            ev.z() = 0.0f;
            float ev_length = ev.length();
            if (ev_length>0.0f)
            {
                mat.makeIdent();
                //float rotation_zrotation_z = atan2f(ev.x(),ev.y());
                //mat.makeRot(rotation_z*180.0f/M_PI,0.0f,0.0f,1.0f);
                float inv = 1.0f/ev_length;
                float c = ev.y()*inv;
                float s = ev.x()*inv;
                mat(0,0) = c;
                mat(0,1) = -s;
                mat(1,0) = s;
                mat(1,1) = c;
            }
            break;
        }
        case(POINT_ROT_WORLD):
        case(POINT_ROT_EYE):
        {
            // currently treat both POINT_ROT_WORLD and POINT_ROT_EYE the same,
            // this is only a temporary and 'incorrect' implementation, will
            // implement fully on second pass of Billboard.
            // Will also need up vector to calc POINT_ROT_EYE, so this will
            // have to be added to the above method paramters.
            // Robert Osfield, Jan 2001.

            Vec3 ev = pos_local-eye_local;
            ev.normalize();

            float ev_len = ev.length();
            if (ev_len != 0.0f)
            {
                ev /= ev_len;

                Vec3 cp = ev^Vec3(0.0f,1.0f,0.0f);
                float dot = ev*Vec3(0.0f,1.0f,0.0f);

                float cp_len = cp.length();
                if (cp_len != 0.0f)
                {
                    cp /= cp_len;

                    float rotation_cp = acosf(dot);
                    mat.makeRot(rotation_cp*180.0f/M_PI,cp[0],cp[1],cp[2]);
                }
            }
            break;
        }
    }
}


void Billboard::calcTransform(const Vec3& eye_local, const Vec3& pos_local,Matrix& mat) const 
{
    //    mat.makeTrans(pos_local[0],pos_local[1],pos_local[2]);
    //    mat.makeIdent();
    calcRotation(eye_local,pos_local,mat);

    //    mat.postTrans(pos_local[0],pos_local[1],pos_local[2]);
    mat(3,0) += pos_local[0];
    mat(3,1) += pos_local[1];
    mat(3,2) += pos_local[2];

}

const bool Billboard::computeBound() const
{
    int i;
    int ngsets = _drawables.size();

    if( ngsets == 0 ) return false;

    _bsphere._center.set(0.0f,0.0f,0.0f);

    for( i = 0; i < ngsets; i++ )
    {
        const Drawable *gset = _drawables[i].get();
        const BoundingBox& bbox = gset->getBound();

        _bsphere._center += bbox.center();
        _bsphere._center += _positionList[i];
    }

    _bsphere._center /= (float)(ngsets);

    float maxd = 0.0;
    for( i = 0; i < ngsets; ++i )
    {
        const Drawable *gset = _drawables[i].get();
        const BoundingBox& bbox = gset->getBound();
        Vec3 local_center = _bsphere._center-_positionList[i];
        for(unsigned int c=0;c<8;++c)
        {
            float d = (bbox.corner(c)-local_center).length2();
            if( d > maxd ) maxd = d;
        }
    }
    _bsphere._radius = sqrtf(maxd);

    _bsphere_computed=true;

    return true;
}