# IDLE
sub idle {
    if (((tv_interval($time{key}))>=0.1) and ($time_real)) {
        $options{time}=$time_real;
        $time_real="";
    }

    if (!glIsList($tsize+1)) {
        if ($zsize < $options{zres}) {
            if ($options{mode} == 1) {
                idle_2d();
                display(1);
            }
            if ($options{mode} >= 2) {
                idle_3d();
                if ($zsize == $options{zres}) {
                    display(1);
                }
            }
        }
        if ($zsize == $options{zres}) {
           if ($options{time} == 0) { usleep (0.001); }
           elsif (($options{time} == 1) and ($tsize < ($options{tres}-1))) { reset_all(1); $t += ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize++; }
           elsif (($options{time} == 2) and ($tsize > 0)) { reset_all(1); $t -= ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize--; }
           elsif ($options{time} == 1) { $options{time}=2; reset_all(1); $t -= ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize--; }
           elsif ($options{time} == 2) { $options{time}=1; reset_all(1); $t += ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize++; }
        }
    }
    elsif ($options{time}) {
        display(1);
        if (($options{time} == 1) and ($tsize < ($options{tres}-1))) { reset_all(1); $t += ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize++; }
        elsif (($options{time} == 2) and ($tsize > 0)) { reset_all(1); $t -= ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize--; }
        elsif ($options{time} == 1) { $options{time}=2; reset_all(1); $t -= ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize--; }
        elsif ($options{time} == 2) { $options{time}=1; reset_all(1); $t += ($options{tmax}-$options{tmin})/($options{tres}-1); $tsize++; }
    }
    else { usleep (0.001); }

}


# SUB IDLE (2D)
sub idle_2d {
    my (@tripar,$x,$y,$j,$eval_block);
    $x=$options{xmin};
    $j=0;
    
    $eval_block= '
    while ($j<=(2*$options{xres}-2)) {
    ';
    $eval_block.= "\$y = $yreal[$n];";
    $eval_block.= '
        $tripar[$j]=$x;
        $tripar[$j+1]=$y;
        $x += ($options{xmax}-$options{xmin})/($options{xres}-1); 
        $j=$j+2;
    }
    return 1;
    ';
    
    while ($j<=(2*$options{xres}-2)){
        last if eval($eval_block);
        $tripar[$j]=$x;
        $tripar[$j+1]=0;
        $x += ($options{xmax}-$options{xmin})/($options{xres}-1);
        $j=$j+2;
    }
    
    $j = 0;
    $zsize = $options{zres} + 1;

    unshift(@tri2d,@tripar); 
    splice(@tri2d,(2*$options{xres})); 
}    


# SUB IDLE (3D)
sub idle_3d {
    my (@tripar,$x,$y,$j,$eval_block);
    $x=$options{xmin};
    $j=0;
    
    $eval_block='
    while ($j<=(3*$options{xres}-3)) {
    ';
    $eval_block.= "\$y = $yreal[$n];";
    $eval_block.= '
        $tripar[$j]=$x;
        $tripar[$j+1]=$y;
        $tripar[$j+2]=$z;
        $x += ($options{xmax}-$options{xmin})/($options{xres}-1); 
        $j=$j+3;
    }
    return 1;
    ';
    
    while ($j<=(3*$options{xres}-3)){
        last if eval($eval_block);
        $tripar[$j]=$x;
        $tripar[$j+1]=0;
        $tripar[$j+2]=$z;
        $x += ($options{xmax}-$options{xmin})/($options{xres}-1);
        $j=$j+3;
    }

    $j = 0;
    $z += ($options{zmax}-$options{zmin})/($options{zres}-1); 
    $zsize++; # IMPORTANT !!!!

    unshift(@tri3d,@tripar); 
    splice(@tri3d,(9*$options{xres}*$options{zres})); 
}
1;