如何检查GLUT中是否未按下键？

Question

我在 OpenGL 中制作游戏，现在我的相机出现错误：

• 如果我按shift+l 或shift+k（移动相机），相机将一直移动，直到我按下另一个键。

要测试我的相机，请在 if 语句中的 playerCameraFunc() 函数之后的显示函数中添加 createKillerBlock(x, y)（例如，createKillerBlock(20, 20)）。

这是我的代码：

#include <stdbool.h>

#include <GL/glut.h>

#define WINDOW_X 1920
#define WINDOW_Y 1080

#define DEFAULT_PLAYER_SPAWN_X 3.0
#define DEFAULT_PLAYER_SPAWN_Y 3.0

#define DEFAULT_CAMERA_X 0.0
#define DEFAULT_CAMERA_Y 0.0

#define UNKILLABLE_LOCATION 1.01

bool isGameStart = false;

int shiftLPresses = 0;
int shiftKPresses = 0;
int shiftXPresses = 0;
int shiftCPresses = 0;

char pressedKey1, pressedKey2;

float blockSize = 10;

float playerX = DEFAULT_PLAYER_SPAWN_X;
float playerY = DEFAULT_PLAYER_SPAWN_Y;

float playerR = 255;
float playerG = 255;
float playerB = 255;

float playerMoveSpeed = 0.7;

float cameraX = DEFAULT_CAMERA_X;
float cameraY = DEFAULT_CAMERA_Y;

float cameraMoveSpeed = 7.1;

float killerBlockX = UNKILLABLE_LOCATION;
float killerBlockY = UNKILLABLE_LOCATION;

float killerBlockR = 255;
float killerBlockG = 0;
float killerBlockB = 0;

void gameMenu()
{
    if (isGameStart == false)
    {
        glBegin(GL_LINES);
        glColor3f(1.0, 1.0, 1.0);
        glVertex2f(-0.2, -0.2);
        glVertex2f(0.2, -0.2);
        glVertex2f(0.2, -0.2);
        glVertex2f(0.2, 0.2);
        glVertex2f(0.2, 0.2);
        glVertex2f(-0.2, 0.2);
        glVertex2f(-0.2, 0.2);
        glVertex2f(-0.2, -0.2);
        glEnd();
        glBegin(GL_POLYGON);
        glVertex2f(-0.1, -0.1);
        glVertex2f(0.1, 0.0);
        glVertex2f(-0.1, 0.1);
        glEnd();
    }
}

void startGame()
{
    isGameStart = true;
}

void spawnPlayer()
{
    glBegin(GL_POLYGON);
    glColor3f(playerR / 255, playerG / 255, playerB / 255);
    glVertex2f(-1.0 + (playerX * (blockSize / WINDOW_X)), -1.0 + (playerY * (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (playerX * (blockSize / WINDOW_X) + (blockSize / WINDOW_X)), -1.0 + (playerY * (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (playerX * (blockSize / WINDOW_X) + (blockSize / WINDOW_X)), -1.0 + (playerY * (blockSize / WINDOW_Y) + (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (playerX * (blockSize / WINDOW_X)), -1.0 + (playerY * (blockSize / WINDOW_Y) + (blockSize / WINDOW_Y)));
    glEnd();
}

void playerCameraFunc()
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glTranslatef(cameraX * (blockSize / WINDOW_X), cameraY * (blockSize / WINDOW_Y), 0);
}

void killPlayer()
{
    isGameStart = false;
    pressedKey1 = '\0';
    pressedKey2 = '\0';
    playerX = DEFAULT_PLAYER_SPAWN_X;
    playerY = DEFAULT_PLAYER_SPAWN_Y;
    cameraX = DEFAULT_CAMERA_X;
    cameraY = DEFAULT_CAMERA_Y;
    glutPostRedisplay();
}

void playerKillFunc()
{
    if (playerX >= killerBlockX - 1.0 & playerY >= killerBlockY - 1.0 & playerX < killerBlockX + 1.0 & playerY <= killerBlockY + 1.0)
    {
        if (killerBlockX != UNKILLABLE_LOCATION & killerBlockY != UNKILLABLE_LOCATION)
        {
            killPlayer();
        }
    }
}

void createKillerBlock(int x, int y)
{
    killerBlockX = x;
    killerBlockY = y;
    glBegin(GL_POLYGON);
    glColor3f(killerBlockR / 255, killerBlockG / 255, killerBlockB / 255);
    glVertex2f(-1.0 + (x * (blockSize / WINDOW_X)), -1.0 + (y * (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (x * (blockSize / WINDOW_X) + (blockSize / WINDOW_X)), -1.0 + (y * (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (x * (blockSize / WINDOW_X) + (blockSize / WINDOW_X)), -1.0 + (y * (blockSize / WINDOW_Y) + (blockSize / WINDOW_Y)));
    glVertex2f(-1.0 + (x * (blockSize / WINDOW_X)), -1.0 + (y * (blockSize / WINDOW_Y) + (blockSize / WINDOW_Y)));
    glEnd();
    playerKillFunc();
}

void timer1()
{
    glutTimerFunc(1000 / 60, timer1, 0);
    switch (pressedKey1)
    {
        case 'w':
            if (isGameStart == true)
            {
                playerY += playerMoveSpeed / (60 * (shiftXPresses + 1) / (shiftCPresses + 1));
            }
            break;
        case 'a':
            if (isGameStart == true)
            {
                playerX -= playerMoveSpeed / (60 * (shiftXPresses + 1) / (shiftCPresses + 1));;
            }
            break;
        case 's':
            if (isGameStart == true)
            {
                playerY -= playerMoveSpeed / (60 * (shiftXPresses + 1) / (shiftCPresses + 1));
            }
            break;
        case 'd':
            if (isGameStart == true)
            {
                playerX += playerMoveSpeed / (60 * (shiftXPresses + 1) / (shiftCPresses + 1));
            }
            break;
    }
    glutPostRedisplay();
}

void timer2()
{
    glutTimerFunc(1000 / 60, timer2, 0);
    switch (pressedKey2)
    {
        case 76:
            if (isGameStart == true)
            {
                cameraX -= cameraMoveSpeed / (60 * (shiftLPresses + shiftKPresses + 1));
                playerX += cameraMoveSpeed / (60 * (shiftLPresses + shiftKPresses + 1));
            }
            break;
        case 75:
            if (isGameStart == true)
            {
                cameraX += cameraMoveSpeed / (60 * (shiftKPresses + shiftLPresses + 1));
                playerX -= cameraMoveSpeed / (60 * (shiftKPresses + shiftLPresses + 1));
            }
            break;
    }
    glutPostRedisplay();
}

void display()
{
    glClear(GL_COLOR_BUFFER_BIT);
    gameMenu();
    if (isGameStart == true)
    {
        spawnPlayer();
        playerCameraFunc();
    }
    glFlush();
}

void keyboard(unsigned char key, int x, int y)
{
    switch (key)
    {
        case 'w':
            if (isGameStart == true)
            {
                pressedKey1 = 'w';
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 'a':
            if (isGameStart == true)
            {
                pressedKey1 = 'a';
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 's':
            if (isGameStart == true)
            {
                pressedKey1 = 's';
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 'd':
            if (isGameStart == true)
            {
                pressedKey1 = 'd';
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 76:
            if (isGameStart == true)
            {
                shiftLPresses += 1;
                pressedKey2 = 76;
                timer2();
            }
            break;
        case 75:
            if (isGameStart == true)
            {
                shiftKPresses += 1;
                pressedKey2 = 75;
                timer2();
            }
            break;
        case 88:
            if (isGameStart == true)
            {
                shiftXPresses += 1;
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 67:
            if (isGameStart == true)
            {
                shiftCPresses += 1;
                pressedKey2 = '\0';
                timer1();
            }
            break;
        case 13:
            if (isGameStart == false)
            {
                startGame();
                timer1();
            }
            break;
        default:
            pressedKey2 = '\0';
    }
    glutPostRedisplay();
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE);
    glutCreateWindow("OpenAttack1");
    glutFullScreen();
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutSetCursor(GLUT_CURSOR_NONE);
    glutMainLoop();
}

编辑

如果按下shift+l 或shift+k 键，我想移动相机，但如果未按下shift+l 或shift+k，则停止移动相机。

Answer 1

升级到 GLUT 4+ 实现，例如 FreeGLUT 并注册 glutKeyboardUpFunc()/glutSpecialUpFunc() 回调以在释放键时获得通知：

3.4.4 Changes to Callbacks

添加了几个新的回调，并且几个特定于 Silicon Graphics 硬件的回调尚未实现。大多数或所有新回调都列在 GLUT 版本 4“glut.h”头文件中，但未将其纳入文档。 新的回调包括常规和特殊的按键释放回调、一个操纵杆回调、一个菜单状态回调（一个参数，不同于具有三个参数的菜单状态回调）、一个窗口状态回调（也一个参数）和一个窗口位置回调。不支持的回调是两个 Tablet 回调。如果用户需要不支持的回调，他应该联系 freeglut 开发团队。

Usage example.