public function line(x1:Float, y1:Float, z1:Float, x2:Float, y2:Float, z2:Float) {

        if (lines >= maxLines) { end(); begin(); }

        var camera = iron.Scene.active.camera;
        var l = camera.right();
        l.add(camera.up());

        var i = lines * 24; // 4 * 6 (structure len)
        vbData.set(i + 0, x1);
        vbData.set(i + 1, y1);
        vbData.set(i + 2, z1);
        vbData.set(i + 3, 1.0);
        vbData.set(i + 4, 0.0);
        vbData.set(i + 5, 0.0);

        vbData.set(i + 6, x2);
        vbData.set(i + 7, y2);
        vbData.set(i + 8, z2);
        vbData.set(i + 9, 1.0);
        vbData.set(i + 10, 0.0);
        vbData.set(i + 11, 0.0);

        vbData.set(i + 12, x2 + strength * l.x);
        vbData.set(i + 13, y2 + strength * l.y);
        vbData.set(i + 14, z2 + strength * l.z);
        vbData.set(i + 15, 1.0);
        vbData.set(i + 16, 0.0);
        vbData.set(i + 17, 0.0);

        vbData.set(i + 18, x1 + strength * l.x);
        vbData.set(i + 19, y1 + strength * l.y);
        vbData.set(i + 20, z1 + strength * l.z);
        vbData.set(i + 21, 1.0);
        vbData.set(i + 22, 0.0);
        vbData.set(i + 23, 0.0);

        i = lines * 6;
        ibData[i + 0] = lines * 4 + 0;
        ibData[i + 1] = lines * 4 + 1;
        ibData[i + 2] = lines * 4 + 2;
        ibData[i + 3] = lines * 4 + 2;
        ibData[i + 4] = lines * 4 + 3;
        ibData[i + 5] = lines * 4 + 0;

        lines++;
    }