游戏开发/渲染与游戏引擎/OpenGL/GLUT/处理输入指南

键盘

键盘按下

此函数处理按键按下时调用的函数。

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
}

键盘抬起

此函数处理按键释放时调用的函数。

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
}

一些不可见字符

键盘按下和键盘抬起可以用来获取一些'不可见'字符，例如退格键和删除键，请查看 ascii 表，值 0-31 和 127。对于那些没有出现在那里的字符，请查看特殊键盘输入。

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

特殊键盘输入

它用于那些没有与之关联的 ascii 字符的键盘输入（例如，向上箭头、F1）。

对于每个键组合，你应该查看此参考，以了解你需要使用的键的名称。

你还可以查看参考列表，以了解你可以使用的修饰符。

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;
    }
}

修饰符^[1]

状态

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

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.

特殊键^[2]

状态

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
}

没有找到你正在寻找的键？这可能是因为它仍然是 ascii 字符（查看值 0-31 和 127），因此可以通过键盘按下和键盘抬起访问。

鼠标

鼠标点击

设置鼠标点击时调用的函数。

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
}

参数 button

button == GLUT_LEFT_BUTTON - 鼠标左键点击
button == GLUT_RIGHT_BUTTON - 鼠标右键点击
button == GLUT_MIDDLE_BUTTON - 鼠标中键点击/鼠标滚轮点击
button == 3 - 鼠标滚轮向上滚动 (还有另一种检测方法)
button == 4 - 鼠标滚轮向下滚动 (还有另一种检测方法)

参数 state

state == GLUT_DOWN - 按钮类型已被按下
state == GLUT_UP - 按钮类型已被释放

鼠标移动

这将处理鼠标移动的情况。

这将包含两个函数，它们执行以下操作

glutMotionFunc

在鼠标移动并且鼠标被点击（拖动）时调用。

glutPassiveMotionFunc

在鼠标移动并且鼠标没有被点击（通常是移动）时调用。

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

如果你想要对所有类型的鼠标移动（点击和未点击）调用相同的函数，这是一种替代代码。

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.
}

鼠标滚轮滚动

这是检测鼠标滚轮移动的另一种方法 (另一种方法).

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]

键盘