0

ゲームの効果音の音量を設定しています。ボリュームを 0.0 から 1.0 まで 0.1 ずつ増やしたい。

ただし、ゼロに達すると、代わりにログに -0.00000 であり、カウントダウンが続行されることが示されます。何が悪いのか教えてください。ありがとう

-(void)sfxUp{
     NSLog(@"SFX UP %f",[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]);
    if ([[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"] == 1.0f)
        return;
    [[NSUserDefaults standardUserDefaults]setFloat:([[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]+0.1f) forKey:@"sfx_volume"];
    [[NSUserDefaults standardUserDefaults]synchronize];
    [[SimpleAudioEngine sharedEngine] setEffectsVolume:[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]];
    NSLog(@"SFX UP %f",[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]);
}
-(void)sfxDown{
    NSLog(@"SFX DOWN %f",[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]);
    if ([[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"] == 0.0f)
        return;
    [[NSUserDefaults standardUserDefaults]setFloat:([[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]-0.1f) forKey:@"sfx_volume"];
    [[NSUserDefaults standardUserDefaults]synchronize];
    [[SimpleAudioEngine sharedEngine] setEffectsVolume:[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]];
     NSLog(@"SFX DOWN %f",[[NSUserDefaults standardUserDefaults]floatForKey:@"sfx_volume"]);
}

「音量を下げる」ボタンのみをクリックすると、これが私のログ出力です。

2012-06-13 18:32:25.067 Bomb Defuse[80558:1c403] SFX DOWN 1.000000
2012-06-13 18:32:25.068 Bomb Defuse[80558:1c403] SFX DOWN 0.900000
2012-06-13 18:32:25.385 Bomb Defuse[80558:1c403] SFX DOWN 0.900000
2012-06-13 18:32:25.386 Bomb Defuse[80558:1c403] SFX DOWN 0.800000
2012-06-13 18:32:25.623 Bomb Defuse[80558:1c403] SFX DOWN 0.800000
2012-06-13 18:32:25.624 Bomb Defuse[80558:1c403] SFX DOWN 0.700000
2012-06-13 18:32:25.873 Bomb Defuse[80558:1c403] SFX DOWN 0.700000
2012-06-13 18:32:25.874 Bomb Defuse[80558:1c403] SFX DOWN 0.600000
2012-06-13 18:32:26.116 Bomb Defuse[80558:1c403] SFX DOWN 0.600000
2012-06-13 18:32:26.140 Bomb Defuse[80558:1c403] SFX DOWN 0.500000
2012-06-13 18:32:26.346 Bomb Defuse[80558:1c403] SFX DOWN 0.500000
2012-06-13 18:32:26.348 Bomb Defuse[80558:1c403] SFX DOWN 0.400000
2012-06-13 18:32:26.605 Bomb Defuse[80558:1c403] SFX DOWN 0.400000
2012-06-13 18:32:26.608 Bomb Defuse[80558:1c403] SFX DOWN 0.300000
2012-06-13 18:32:26.835 Bomb Defuse[80558:1c403] SFX DOWN 0.300000
2012-06-13 18:32:26.838 Bomb Defuse[80558:1c403] SFX DOWN 0.200000
2012-06-13 18:32:27.068 Bomb Defuse[80558:1c403] SFX DOWN 0.200000
2012-06-13 18:32:27.069 Bomb Defuse[80558:1c403] SFX DOWN 0.100000
2012-06-13 18:32:27.319 Bomb Defuse[80558:1c403] SFX DOWN 0.100000
2012-06-13 18:32:27.338 Bomb Defuse[80558:1c403] SFX DOWN -0.000000
2012-06-13 18:32:27.630 Bomb Defuse[80558:1c403] SFX DOWN -0.000000
2012-06-13 18:32:27.640 Bomb Defuse[80558:1c403] SFX DOWN -0.100000
2012-06-13 18:32:27.946 Bomb Defuse[80558:1c403] SFX DOWN -0.100000
2012-06-13 18:32:27.947 Bomb Defuse[80558:1c403] SFX DOWN -0.200000
2012-06-13 18:32:28.170 Bomb Defuse[80558:1c403] SFX DOWN -0.200000
2012-06-13 18:32:28.172 Bomb Defuse[80558:1c403] SFX DOWN -0.300000
2012-06-13 18:32:28.414 Bomb Defuse[80558:1c403] SFX DOWN -0.300000
2012-06-13 18:32:28.416 Bomb Defuse[80558:1c403] SFX DOWN -0.400000
2012-06-13 18:32:28.641 Bomb Defuse[80558:1c403] SFX DOWN -0.400000
2012-06-13 18:32:28.643 Bomb Defuse[80558:1c403] SFX DOWN -0.500000
2012-06-13 18:32:28.869 Bomb Defuse[80558:1c403] SFX DOWN -0.500000
2012-06-13 18:32:28.870 Bomb Defuse[80558:1c403] SFX DOWN -0.600000
2012-06-13 18:32:29.301 Bomb Defuse[80558:1c403] SFX DOWN -0.600000
2012-06-13 18:32:29.303 Bomb Defuse[80558:1c403] SFX DOWN -0.700000
2012-06-13 18:32:29.584 Bomb Defuse[80558:1c403] SFX DOWN -0.700000
2012-06-13 18:32:29.586 Bomb Defuse[80558:1c403] SFX DOWN -0.800000

編集：

>= および <= (それぞれ) に変更すると、次の出力が得られます。

2012-06-13 18:45:34.574 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:35.135 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:35.529 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:35.877 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.057 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.229 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.391 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.542 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.717 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:36.897 Bomb Defuse[80607:1c403] BG UP 1.000000
2012-06-13 18:45:37.599 Bomb Defuse[80607:1c403] BG DOWN1.000000
2012-06-13 18:45:37.602 Bomb Defuse[80607:1c403] BG DOWN0.900000
2012-06-13 18:45:38.431 Bomb Defuse[80607:1c403] BG DOWN0.900000
2012-06-13 18:45:38.491 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:38.617 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:38.951 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:39.125 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:39.479 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:39.908 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:40.399 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:40.624 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:40.841 Bomb Defuse[80607:1c403] BG DOWN-0.100000
2012-06-13 18:45:41.059 Bomb Defuse[80607:1c403] BG DOWN-0.100000
4

1 に答える 1

7

浮動小数点演算は正確ではありません。1.0から始めて0.1を10回引くと、必ずしも正確に0.0になるとは限りません。詳細については、古典的な論文「すべてのコンピューター科学者が浮動小数点演算について知っておくべきこと」をお読みください。

これを回避するには、値を変更したときに上限を設定するか[0.0, 1.0]、厳密な等式比較を回避するか（たとえば、を使用する>=か、<=代わりに==）、または-理想的には-ボリュームを0から10までの整数として格納し、除算します。必要に応じて10.0まで。

于 2012-06-13T22:41:32.010 に答える