遊戲開發/渲染與遊戲引擎/OpenGL/GLUT/處理輸入指南

鍵盤

鍵盤按下

此函式處理按鍵按下時呼叫的函式。

void InitScene(){
    //Other functions will be here
    glutKeyboardFunc(KeyboardDown); //Telling glut what function to call when the event occurs
}


void KeyboardDown(unsigned char key, int x, int y){ 
                  //key - The ascii value of the key that's pressed
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a key is pressed down
}

鍵盤抬起

此函式處理按鍵釋放時呼叫的函式。

void InitScene(){
    //Other functions will be here
    glutKeyboardUpFunc(KeyboardUp); //Telling glut what function to call when the event occurs
}


void KeyboardUp(unsigned char key, int x, int y){ 
                  //key - The ascii value of the key that's pressed
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a key is released
}

一些不可見字元

鍵盤按下和鍵盤抬起可以用來獲取一些'不可見'字元，例如退格鍵和刪除鍵，請檢視 ascii 表，值 0-31 和 127。對於那些沒有出現在那裡的字元，請檢視特殊鍵盤輸入。

示例用法

if (key == 8){} //Backspace has been pressed
if (key == 9){} //TAB has been pressed
if (key == 10){} //Enter has been pressed
if (key == 27){} //Escape has been pressed
if (key == 127){} //Delete has been pressed

特殊鍵盤輸入

它用於那些沒有與之關聯的 ascii 字元的鍵盤輸入（例如，向上箭頭、F1）。

對於每個鍵組合，你應該檢視此參考，以瞭解你需要使用的鍵的名稱。

你還可以檢視參考列表，以瞭解你可以使用的修飾符。

void InitScene(){
    //Other functions will be here
    glutSpecialFunc(KeyboardSpecial); //Telling glut what function to call when the event occurs
}


void KeyboardSpecial(int key, int x, int y){
                  //key - The id code of the keypress
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what happens when a key is pressed

    //Example code:
    int modifiers = glutGetModifiers(); //Get if ctrl, alt or shift are pressed can use:if if (modifiers == (GLUT_ACTIVE_CTRL | GLUT_ACTIVE_ALT | GLUT_ACTIVE_SHIFT))
    switch(key){
    case GLUT_KEY_F2 :
        cout << "F2 was pressed." << endl;
        break;
    case GLUT_KEY_UP :
        cout << "The up arrow was pressed." << endl;
        break;
    case GLUT_KEY_INSERT : 
	if (modifiers == (GLUT_ACTIVE_CTRL | GLUT_ACTIVE_ALT)){
	    cout << "Pressed Insert " << "with only Ctrl and Alt" << endl;
	}else if (modifiers & GLUT_ACTIVE_CTRL && modifiers & GLUT_ACTIVE_ALT){
	    cout << "Pressed Insert " << "with Ctrl and Alt" << endl;
        }
	break;
    
    case GLUT_KEY_F1 :
	ignoreRepeats = !ignoreRepeats;
	glutIgnoreKeyRepeat(ignoreRepeats); //This will tell GLUT whether or not to call this function again if the key is pressed twice in a row.
	
	if (ignoreRepeats)
		cout << "Repeates disabled" << endl;
	else
		cout << "Repeats enabled" << endl;
	break;
    }
}

修飾符^[1]

狀態

GLUT_ACTIVE_SHIFT - Shift 鍵是否被按下？
GLUT_ACTIVE_CTRL - Ctrl 鍵是否被按下？
GLUT_ACTIVE_ALT - Alt 鍵是否被按下？

使用方法

int modifiers = glutGetModifiers();

if (modifiers == GLUT_ACTIVE_SHIFT){} //If shift is being pressed.
if (modifiers == GLUT_ACTIVE_CTRL | GLUT_ACTIVE_ALT){} //If ctrl <u>and</u> alt are being pressed.

特殊鍵^[2]

狀態

GLUT_KEY_F1 到 GLUT_KEY_F12
GLUT_KEY_LEFT
GLUT_KEY_UP
GLUT_KEY_RIGHT
GLUT_KEY_DOWN
GLUT_KEY_PAGE_UP
GLUT_KEY_PAGE_DOWN
GLUT_KEY_HOME
GLUT_KEY_END
GLUT_KEY_INSERT

使用方法

void KeyboardSpecial(int key, int x, int y){
    if (key == GLUT_KEY_LEFT){} //Left arrow key
}

沒有找到你正在尋找的鍵？這可能是因為它仍然是 ascii 字元（檢視值 0-31 和 127），因此可以透過鍵盤按下和鍵盤抬起訪問。

滑鼠

滑鼠點選

設定滑鼠點選時呼叫的函式。

void InitScene(){
    //Other functions will be here
    glutMouseFunc(MouseClicked); //Telling glut what function to call when the event occurs
}


void MouseClicked(int button, int state, int x, int y){ 
                  //button - The id of the button on the mouse that's clicked, see below for IDs of buttons
                  //state - is it being pressed or released?, see below for possible states
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a button on the mouse is clicked
}

引數 button

button == GLUT_LEFT_BUTTON - 滑鼠左鍵點選
button == GLUT_RIGHT_BUTTON - 滑鼠右鍵點選
button == GLUT_MIDDLE_BUTTON - 滑鼠中鍵點選/滑鼠滾輪點選
button == 3 - 滑鼠滾輪向上滾動 (還有另一種檢測方法)
button == 4 - 滑鼠滾輪向下滾動 (還有另一種檢測方法)

引數 state

state == GLUT_DOWN - 按鈕型別已被按下
state == GLUT_UP - 按鈕型別已被釋放

滑鼠移動

這將處理滑鼠移動的情況。

這將包含兩個函式，它們執行以下操作

glutMotionFunc

在滑鼠移動並且滑鼠被點選（拖動）時呼叫。

glutPassiveMotionFunc

在滑鼠移動並且滑鼠沒有被點選（通常是移動）時呼叫。

void InitScene(){
    //Other functions will be here
    glutMotionFunc(MouseMoveAndClicked); //Telling glut what function to call when the event occurs
    glutPassiveMotionFunc(MouseMoveAndUnClicked); //Telling glut what function to call when the event occurs
}



void MouseMoveAndClicked(int x, int y){ 
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a the mouse is moving and being clicked (dragging).
}

void MouseMoveAndUnClicked(int x, int y){ 
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a the mouse is moving and NOT being clicked
}

替代方案

如果你想要對所有型別的滑鼠移動（點選和未點選）呼叫相同的函式，這是一種替代程式碼。

void InitScene(){
    //Other functions will be here
    glutMotionFunc(MouseMoving); //Telling glut what function to call when the event occurs
    glutPassiveMotionFunc(MouseMoving); //Telling glut what function to call when the event occurs
}



void MouseMoving(int x, int y){ 
                  //x - The x coordinate of the mouse when it was pressed
                  //y - The y coordinate of the mouse when it was pressed

    //Handle what will happen when a the mouse is moving.
}

滑鼠滾輪滾動

這是檢測滑鼠滾輪移動的另一種方法 (另一種方法).

void InitScene(){
    //Other functions will be here
    glutMouseWheelFunc(mouseWheel); //Telling glut what function to call when the event occurs
}

void mouseWheel(int button, int dir, int x, int y)
{
    if (dir > 0){
        // Zoom in
    }else if (dir < 0){
        // Zoom out
    }
    return;
}

[1] ttps://www.opengl.org/resources/libraries/glut/spec3/node73.html

[2] ttps://www.opengl.org/resources/libraries/glut/spec3/node54.html

[1]

[2]

鍵盤