在保龄球比赛中，一旦按下一个键，就移动一个球

我一直在用C++处理保龄球游戏。

我只想要一件事，我只想在按下一个键并且碗平稳移动时移动球（不像现在那样，它通过按下并按住UP-key来移动）。

这是代码：-

#include <GL/glut.h>
#include <cmath>
GLfloat posX = 0.07, posY = 0.1, posZ = 0.0,
firstx1 = 0.02, firsty1 = 0.3, firstx2 = 0.07, firsty2 = 0.3, firstx3 = 0.11, firsty3 = 0.3,
secondx1 = -0.16, secondy1 = 0.3, secondx2 = -0.21, secondy2 = 0.3, secondx3 = -0.27, secondy3 = 0.3,
thirdx1 = 0.3, thirdy1 = 0.3, thirdx2 = 0.35, thirdy2 = 0.3, thirdx3 = 0.4, thirdy3 = 0.3;

double x, y, angle;
#define PI 3.1415926535898
GLint circle_points = 50;
void bottle() {
    glColor3f(0.0, 0.0, 1.0);
    glPointSize(9.0);
    glBegin(GL_POINTS);
    glVertex3f(firstx1, firsty1, 0.0);
    glVertex3f(firstx2, firsty2, 0.0);
    glVertex3f(firstx3, firsty3, 0.0);
    glVertex3f(secondx1, secondy1, 0.0);
    glVertex3f(secondx2, secondy2, 0.0);
    glVertex3f(secondx3, secondy3, 0.0);
    glVertex3f(thirdx1, thirdy1, 0.0);
    glVertex3f(thirdx2, thirdy2, 0.0);
    glVertex3f(thirdx3, thirdy3, 0.0);
    glEnd();
    glFlush();
}
void circ() {
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_TRIANGLE_FAN);
    for (int i = 0; i <= 300; i++) {
        angle = 2 * PI * i / 300;
        x = cos(angle) / 25;
        y = sin(angle) / 20;
        glVertex2d(x, y);
    }
    glEnd();
}
void display() {
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-1.0, 1.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glPushMatrix();
    bottle();
    glPopMatrix();
    glPushMatrix();
    glTranslatef(posX, posY, posZ);
    circ();
    glPopMatrix();
    glutSwapBuffers();
}
float move_unit = 0.01;
void keyboardown(int key, int x, int y) {
    switch (key) {
    case GLUT_KEY_RIGHT:
        posX += 0.3;
        break;
    case GLUT_KEY_LEFT:
        posX -= 0.3;
        break;
    case GLUT_KEY_UP:
        posY += move_unit;
        break;
    case GLUT_KEY_DOWN:
        posY -= move_unit;
        break;
    default:
        break;
    }
    if ((posX >= firstx1 && posX <= firstx3)
            && (posY == firsty1 && posY == firsty2 && posY == firsty3)) {
        firstx1 += 0.02;
        firsty1 += 0.03;
        firstx2 += -0.06;
        firsty2 += 0.02;
        firstx3 += 0.03;
        firsty3 += 0.05;
    }
    if ((posX <= secondx1 && posX >= secondx3)
                && (posY == secondy1 && posY == secondy2 && posY == secondy3)) {
            secondx1 += 0.02;
            secondy1 += 0.02;
            secondx2 += -0.06;
            secondy2 += 0.02;
            secondx3 += 0.03;
            secondy3 += 0.05;
        }
    if ((posX >= thirdx1 && posX <= thirdx3)
                && (posY == thirdy1 && posY == thirdy2 && posY == thirdy3)) {
            thirdx1 += 0.02;
            thirdy1 += 0.03;
            thirdx2 += -0.07;
            thirdy2 += 0.02;
            thirdx3 += 0.03;
            thirdy3 += 0.05;
        }
    glutPostRedisplay();
}
int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(500, 300);
    glutInitWindowPosition(150,250);
    glutCreateWindow("Balling Game");
    glutDisplayFunc(display);
    glutSpecialFunc(keyboardown);
    glutMainLoop();
}