C++ (Cpp) Matrix::postMult示例

bool AntiSquish::computeUnSquishedMatrix(const osg::NodeVisitor* nv, osg::Matrix& unsquished) const
{
    OpenThreads::ScopedLock<OpenThreads::Mutex> lock( _cacheLock );

    if ( !nv )
    {
        if ( !_cacheDirty )
        {
            unsquished = _cache;
            return true;
        }

        return false;
    }

    osg::NodePath np = nv->getNodePath();

    // Remove the last node which is the anti squish node itself.
    np.pop_back();

    // Get the accumulated modeling matrix.
    const osg::Matrix localToWorld = osg::computeLocalToWorld(np);

    if ( !_cacheDirty && _cacheLocalToWorld==localToWorld )
    {
        unsquished = _cache;
        return true;
    }

    osg::Vec3d t, s;
    osg::Quat r, so;

    localToWorld.decompose(t, r, s, so);

    // Let's take an average of the scale.
    double av = (s[0] + s[1] + s[2])/3.0;
    s[0] = av; s[1] = av; s[2]=av;

    if (av == 0)
        return false;

    //
    // Final Matrix: [-Pivot][SO]^[S][SO][R][T][Pivot][LOCALTOWORLD]^[position]
    // OR [SO]^[S][SO][R][T][LOCALTOWORLD]^
    //
    if (_usePivot)
    {
        unsquished.postMultTranslate(-_pivot);

        osg::Matrix tmps, invtmps;
        so.get(tmps);
        if (!invtmps.invert(tmps))
            return false;

        //SO^
        unsquished.postMult(invtmps);
        //S
        unsquished.postMultScale(s);
        //SO
        unsquished.postMult(tmps);
        //R
        unsquished.postMultRotate(r);
        //T
        unsquished.postMultTranslate(t);

        osg::Matrix invltw;
        if (!invltw.invert(localToWorld))
            return false;

        // LTW^
        unsquished.postMult( invltw );

        // Position
        if (_usePosition)
            unsquished.postMultTranslate(_position);
        else
            unsquished.postMultTranslate(_pivot);
    }
    else
    {
        osg::Matrix tmps, invtmps;
        so.get(tmps);
        if (!invtmps.invert(tmps))
            return false;

        unsquished.postMult(invtmps);
        unsquished.postMultScale(s);
        unsquished.postMult(tmps);
        unsquished.postMultRotate(r);
        unsquished.postMultTranslate(t);
        osg::Matrix invltw;
        if (!invltw.invert(localToWorld))
            return false;
        unsquished.postMult( invltw );
    }

    if (unsquished.isNaN())
        return false;

    _cache = unsquished;
    _cacheLocalToWorld = localToWorld;
    _cacheDirty = false;

    //As Transform::computeBounde calls us without a node-path it relies on
    //The cache. Hence a new _cache affects the bound.
    const_cast<AntiSquish*>(this)->dirtyBound();

    return true;
}