problem with opengl screentoworld java method

    Jan 13 2011 | 9:18 am
    I'm quite new to java and mxj programming and y try to make a simple opengl GUI
    drawing linesegments with mouse. That's why i have to translate screencoordinates of an array of segments in opengl coordinates, but when i try to use the screentoworld method like that:
    Atom[] a = render.send("screentoworld", new float[] {(float)this.a.xe, (float), 0.0f});
    float worldpoint_a[] = new float[] { a[0].toFloat(),
    a[1].toFloat(), a[2].toFloat() };
    outlet(0, worldpoint_a); //for debugging
    i can't recover anything but 0. 0. 0. from outlet 0.
    My java class is constructed like the exemple cycling 74 jitgldock and a function bang():
    public void bang() {
    for (int i = 0; i < Drawn.size() - 1; i++) {
    Segment tempor = (Segment) Drawn.get(i);
    and i make the coordinates translation in the Segment.Display() method.
    Is there something i do wrong, or special render ( attributes to set up or a very strict way to do this in order to make the screentoworld translation efficient?