protected TerrainQuad getQuad(int quad) {
        if (quad == 0)
            return this;
        if (children != null)
            for (int x = children.size(); --x >= 0;) {
                Spatial child = children.get(x);
                if (child instanceof TerrainQuad) {
                    TerrainQuad tq = (TerrainQuad) child;
                    if (tq.getQuadrant() == quad)
                        return tq;
                }
            }
        return null;
    }
lock or unlock the meshes of this terrain.
Locked meshes are uneditable but have better performance.
@param locked or unlocked
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainQuad.java