输入映射
我们在第4节时，使用了一行代码来判断玩家是否按下某个键：
#是否按下左键
if Input.is_action_pressed("ui_left"):
其中，Input类是专门用于处理输入的类，包含鼠标、键盘、手柄的输入。is_action_pressed是检查按个输入映射是否处于正在按下状态。
通过代码可以看到，我们检查了"ui_left"是否按下，那么，这个"ui_left"是如何定义的？
在菜单栏找到项目→项目设置，打开如下界面：
项目设置.png
在项目设置中找到键位映射，接下来，即使我不说，你也应该能猜到这个功能如何使用了。所以这里留给大家自行研究。
输入事件
在第四节中，为了检测空格键发射子弹，我用了以下代码：
#检测发射子弹
if Input.is_action_pressed("ui_select") and cd_timer < 0:
在这里，我使用了自己记录cd的方式来避免玩家一直按着空格，导致每帧发射一个子弹的问题，实际上有更好的解决方案。
接下来我们认识三个检测输入事件的函数：
if Input.is_action_just_pressed(action):
#只有当按键按下那一帧才会判断通过
print("你按下了某键")
if Input.is_action_just_released(action):
#只有当按键释放那一帧才会判断通过
print("你放开了某键")
if Input.is_action_pressed(action):
#只要按键处于按下状态，每一帧都会判断通过
print("你按着某键不松手")
以上三个检测函数，都需要首先在按键映射里事先定义，或者直接使用按钮映射里默认的映射。
除此之外，还有两个函数也比较常用：
if Input.is_key_pressed(scancode):
#某一按键处于按下状态，scancode是按键编号
pass
if Input.is_mouse_button_pressed(button):
#按下鼠标某个按钮，button是按钮编码
pass
附：鼠标键盘按钮编码（很多键我也没有见过，可能是专业级别的设备才有吧）
#鼠标按钮编码
enum ButtonList:
BUTTON_LEFT = 1#鼠标左键
BUTTON_RIGHT = 2#鼠标右键
BUTTON_MIDDLE = 3#鼠标中键
BUTTON_XBUTTON1 = 8#额外的鼠标按钮1(仅在某些鼠标上存在)
BUTTON_XBUTTON2 = 9#额外的鼠标按钮2(仅在某些鼠标上存在)
BUTTON_WHEEL_UP = 4#鼠标滚轮向上
BUTTON_WHEEL_DOWN = 5#鼠标滚轮向下
BUTTON_WHEEL_LEFT = 6#鼠标滚轮左键(仅在某些鼠标上存在)
BUTTON_WHEEL_RIGHT = 7#鼠标滚轮右键(仅在某些鼠标上存在)
BUTTON_MASK_LEFT = 1#鼠标左键蒙版
BUTTON_MASK_RIGHT = 2#鼠标右键蒙版
BUTTON_MASK_MIDDLE = 4#鼠标中键蒙版
BUTTON_MASK_XBUTTON1 = 128#额外的鼠标按钮1个遮罩
BUTTON_MASK_XBUTTON2 = 256#额外的鼠标按钮2遮罩
#键盘按键编码
enum KeyList:
KEY_ESCAPE = 16777217#Esc键
KEY_TAB = 16777218#Tab键
KEY_BACKTAB = 16777219#Shift + Tab键
KEY_BACKSPACE = 16777220#退格键
KEY_ENTER = 16777221#主键盘Enter键
KEY_KP_ENTER = 16777222#数字键盘Enter键
KEY_INSERT = 16777223#Insert键
KEY_DELETE = 16777224#Delete键
KEY_PAUSE = 16777225#Pause键
KEY_PRINT = 16777226#打印屏幕键
KEY_SYSREQ = 16777227#系统请求密钥
KEY_CLEAR = 16777228#Clear键
KEY_HOME = 16777229#Home键
KEY_END = 16777230#End键
KEY_LEFT = 16777231#左箭头键
KEY_UP = 16777232#向上箭头键
KEY_RIGHT = 16777233#向右箭头键
KEY_DOWN = 16777234#向下箭头键
KEY_PAGEUP = 16777235#Page Up键
KEY_PAGEDOWN = 16777236#Page Down键
KEY_SHIFT = 16777237#Shift键
KEY_CONTROL = 16777238#控制键
KEY_META = 16777239#中继键
KEY_ALT = 16777240#ALT键
KEY_CAPSLOCK = 16777241#Caps Lock键
KEY_NUMLOCK = 16777242#Num Lock键
KEY_SCROLLLOCK = 16777243#滚动锁定键
KEY_F1 = 16777244#F1键
KEY_F2 = 16777245#F2键
KEY_F3 = 16777246#F3键
KEY_F4 = 16777247#F4键
KEY_F5 = 16777248#F5键
KEY_F6 = 16777249#F6键
KEY_F7 = 16777250#F7键
KEY_F8 = 16777251#F8键
KEY_F9 = 16777252#F9键
KEY_F10 = 16777253#F10键
KEY_F11 = 16777254#F11键
KEY_F12 = 16777255#F12键
KEY_F13 = 16777256#F13键
KEY_F14 = 16777257#F14键
KEY_F15 = 16777258#F15键
KEY_F16 = 16777259#F16键
KEY_KP_MULTIPLY = 16777345#数字小键盘上的(*)键
KEY_KP_DIVIDE = 16777346#数字键盘上的(/)键
KEY_KP_SUBTRACT = 16777347#数字键盘上的减号(-)键
KEY_KP_PERIOD = 16777348#数字键盘上的句点(.)键
KEY_KP_ADD = 16777349#在数字键盘上添加(+)键
KEY_KP_0 = 16777350#数字键盘上的数字0
KEY_KP_1 = 16777351#数字键盘上的数字1
KEY_KP_2 = 16777352#数字键盘上的数字2
KEY_KP_3 = 16777353#数字键盘上的数字3
KEY_KP_4 = 16777354#数字键盘上的数字4
KEY_KP_5 = 16777355#数字键盘上的数字5
KEY_KP_6 = 16777356#数字键盘上的数字6
KEY_KP_7 = 16777357#数字键盘上的数字7
KEY_KP_8 = 16777358#数字键盘上的数字8
KEY_KP_9 = 16777359#数字键盘上的数字9
KEY_SUPER_L = 16777260#左超级键(Windows键)
KEY_SUPER_R = 16777261#右超级键(Windows键)
KEY_MENU = 16777262#上下文菜单键
KEY_HYPER_L = 16777263#左超级键
KEY_HYPER_R = 16777264#右超级键
KEY_HELP = 16777265#帮助键
KEY_DIRECTION_L = 16777266#左方向键
KEY_DIRECTION_R = 16777267#右方向键
KEY_BACK = 16777280#后退键
KEY_FORWARD = 16777281#前进键
KEY_STOP = 16777282#停止键
KEY_REFRESH = 16777283#刷新密钥
KEY_VOLUMEDOWN = 16777284#降低音量键
KEY_VOLUMEMUTE = 16777285#静音键
KEY_VOLUMEUP = 16777286#调高音量键
KEY_BASSBOOST = 16777287#低音增强键
KEY_BASSUP = 16777288#低音键
KEY_BASSDOWN = 16777289#低音键
KEY_TREBLEUP = 16777290#高音键
KEY_TREBLEDOWN = 16777291#高音下移键
KEY_MEDIAPLAY = 16777292#媒体播放键
KEY_MEDIASTOP = 16777293#媒体停止键
KEY_MEDIAPREVIOUS = 16777294#上一首歌曲的键
KEY_MEDIANEXT = 16777295#下一个歌曲键
KEY_MEDIARECORD = 16777296#媒体记录键
KEY_HOMEPAGE = 16777297#主页键
KEY_FAVORITES = 16777298#收藏夹键
KEY_SEARCH = 16777299#搜索键
KEY_STANDBY = 16777300#备用键
KEY_OPENURL = 16777301#打开URL /启动浏览器键
KEY_LAUNCHMAIL = 16777302#启动邮件密钥
KEY_LAUNCHMEDIA = 16777303#启动媒体密钥
KEY_LAUNCH0 = 16777304#启动快捷方式0键
KEY_LAUNCH1 = 16777305#启动快捷方式1键
KEY_LAUNCH2 = 16777306#启动快捷方式2键
KEY_LAUNCH3 = 16777307#启动快捷键3键
KEY_LAUNCH4 = 16777308#启动快捷方式4键
KEY_LAUNCH5 = 16777309#启动快捷键5键
KEY_LAUNCH6 = 16777310#启动快捷键6键
KEY_LAUNCH7 = 16777311#启动快捷键7键
KEY_LAUNCH8 = 16777312#启动快捷键8键
KEY_LAUNCH9 = 16777313#启动快捷方式9键
KEY_LAUNCHA = 16777314#启动快捷方式A键
KEY_LAUNCHB = 16777315#启动快捷键B
KEY_LAUNCHC = 16777316#启动快捷方式C键
KEY_LAUNCHD = 16777317#启动快捷方式D键
KEY_LAUNCHE = 16777318#启动快捷键E
KEY_LAUNCHF = 16777319#启动快捷键F键
KEY_UNKNOWN = 33554431#未知密钥
KEY_SPACE = 32#空格键
KEY_EXCLAM = 33#! key
KEY_QUOTEDBL = 34#" key
KEY_NUMBERSIGN = 35## key
KEY_DOLLAR = 36#$ key
KEY_PERCENT = 37#% key
KEY_AMPERSAND = 38#& key
KEY_APOSTROPHE = 39# key
KEY_PARENLEFT = 40#( key
KEY_PARENRIGHT = 41#) key
KEY_ASTERISK = 42#退出键
KEY_PLUS = 43#+ key
KEY_COMMA = 44#, key
KEY_MINUS = 45#- key
KEY_PERIOD = 46#.key
KEY_SLASH = 47#/ key
KEY_0 = 48#Number 0
KEY_1 = 49#Number 1
KEY_2 = 50#Number 2
KEY_3 = 51#Number 3
KEY_4 = 52#Number 4
KEY_5 = 53#Number 5
KEY_6 = 54#Number 6
KEY_7 = 55#Number 7
KEY_8 = 56#Number 8
KEY_9 = 57#Number 9
KEY_COLON = 58#: key
KEY_SEMICOLON = 59#; key
KEY_LESS = 60#< key
KEY_EQUAL = 61#= KEY
KEY_GREATER = 62#> key
KEY_QUESTION = 63#! key
KEY_AT = 64#@ key
KEY_A = 65#A key
KEY_B = 66#B key
KEY_C = 67#C key
KEY_D = 68#D key
KEY_E = 69#E key
KEY_F = 70#F key
KEY_G = 71#G key
KEY_H = 72#H key
KEY_I = 73#I key
KEY_J = 74#J key
KEY_K = 75#K key
KEY_L = 76#L key
KEY_M = 77#M key
KEY_N = 78#N key
KEY_O = 79#O key
KEY_P = 80#P key
KEY_Q = 81#Q key
KEY_R = 82#R key
KEY_S = 83#S key
KEY_T = 84#T key
KEY_U = 85#U key
KEY_V = 86#V key
KEY_W = 87#W key
KEY_X = 88#X key
KEY_Y = 89#Y key
KEY_Z = 90#Z key
KEY_BRACKETLEFT = 91#[ key
KEY_BACKSLASH = 92#\ key
KEY_BRACKETRIGHT = 93#] key
KEY_ASCIICIRCUM = 94#^ key
KEY_UNDERSCORE = 95#_ key
KEY_QUOTELEFT = 96#` key
KEY_BRACELEFT = 123#{ key
KEY_BAR = 124#| key
KEY_BRACERIGHT = 125#} key
KEY_ASCIITILDE = 126#~ key
KEY_NOBREAKSPACE = 160#不可破坏的空格键
KEY_EXCLAMDOWN = 161#¡ key
KEY_CENT = 162#¢ key
KEY_STERLING = 163#£ key
KEY_CURRENCY = 164#¤ key
KEY_YEN = 165#¥ key
KEY_BROKENBAR = 166#¦ key
KEY_SECTION = 167#§ key
KEY_DIAERESIS = 168#¨ key
KEY_COPYRIGHT = 169#© key
KEY_ORDFEMININE = 170#ª key
KEY_GUILLEMOTLEFT = 171#« key
KEY_NOTSIGN = 172#¬ key
KEY_HYPHEN = 173#软连字符键
KEY_REGISTERED = 174#® key
KEY_MACRON = 175#¯ key
KEY_DEGREE = 176#° key
KEY_PLUSMINUS = 177#± key
KEY_TWOSUPERIOR = 178#² key
KEY_THREESUPERIOR = 179#³ key
KEY_ACUTE = 180#´ key
KEY_MU = 181#µ key
KEY_PARAGRAPH = 182#¶ key
KEY_PERIODCENTERED = 183#· key
KEY_CEDILLA = 184#¸ key
KEY_ONESUPERIOR = 185#¹ key
KEY_MASCULINE = 186#º key
KEY_GUILLEMOTRIGHT = 187#» key
KEY_ONEQUARTER = 188#¼ key
KEY_ONEHALF = 189#½ key
KEY_THREEQUARTERS = 190#¾ key
KEY_QUESTIONDOWN = 191#¿ key
KEY_AGRAVE = 192#À key
KEY_AACUTE = 193#Á key
KEY_ACIRCUMFLEX = 194#Â key
KEY_ATILDE = 195#Ã key
KEY_ADIAERESIS = 196#Ä key
KEY_ARING = 197#Å key
KEY_AE = 198#Æ key
KEY_CCEDILLA = 199#Ç key
KEY_EGRAVE = 200#È key
KEY_EACUTE = 201#É key
KEY_ECIRCUMFLEX = 202#Ê key
KEY_EDIAERESIS = 203#Ë key
KEY_IGRAVE = 204#Ì key
KEY_IACUTE = 205#Í key
KEY_ICIRCUMFLEX = 206#Î key
KEY_IDIAERESIS = 207#Ï key
KEY_ETH = 208#Ð key
KEY_NTILDE = 209#Ñ key
KEY_OGRAVE = 210#Ò key
KEY_OACUTE = 211#Ó key
KEY_OCIRCUMFLEX = 212#Ô key
KEY_OTILDE = 213#Õ key
KEY_ODIAERESIS = 214#Ö key
KEY_MULTIPLY = 215#× key
KEY_OOBLIQUE = 216#Ø key
KEY_UGRAVE = 217#Ù key
KEY_UACUTE = 218#Ú key
KEY_UCIRCUMFLEX = 219#Û key
KEY_UDIAERESIS = 220#Ü key
KEY_YACUTE = 221#Ý key
KEY_THORN = 222#Þ key
KEY_SSHARP = 223#ß key.KEY_DIVISION = 247#÷ key
KEY_YDIAERESIS = 255#ÿ key