// Change values here
integer alpha = 128;
integer status = TRUE;

default
{
    on_rez(integer p) {llResetScript();}
    touch_start(integer n) {llResetScript();}

    state_entry()
    {
        llSetTexture(osGetMapTexture(), 0);

        string cmd;
        cmd = osSetPenSize(cmd, 3);
        cmd = osSetPenColor(cmd, "White");
        cmd = osMovePen(cmd, 78, 78);
        cmd = osDrawRectangle(cmd, 100, 100);
        // Change alpha value here
        string params = "width:256, height:256, alpha: 128";
        osSetDynamicTextureDataBlendFace("", "vector", cmd, params, status, 2, 0, alpha, 0);
    }
}