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c++ - How I can use Keyboard interaction in this code

问题描述

i want to use keyboard key to move the object on the path but after using keyboard function the object is not moving.Please help me with this.after applying keyboard function the object is not moving from its place.

i want to add 3 different function for wave/path so keyboard interaction is necessary for me, so that i may able to use different keys for different scenes.

void object()
{
    glPushMatrix();
    glTranslatef(x, y, 0);
    glBegin(GL_LINES);
    glColor3f(0, 0, 0);
    glVertex2f(-0.3, 0.1);
    glVertex2f(0.3, 0.1);        
    glEnd();
    glPopMatrix();
    glFlush();
}

void drawsine()
{   glBegin(GL_LINE_STRIP);//Primitive
    glColor3f(255, 0, 0);//Set drawing color 
    int i = 0;
    float x = 0, y = 0;
    for (x = -5; x < 6; x = x + 0.1)
    {   y = (sin(3.142*x)) / 3.142*x;
        glVertex2f(x, y);
        sinex[i] = x;
        siney[i] = y;
        i++;}
    glEnd();
    glFlush();
}

void doFrame(int v) {
    //x = sinex[i];
    //y = siney[i];
    if (x < 5.9)
    {
        x += 0.1;
        y = (sin(3.142*x)) / 3.142*x;
    }
    glutPostRedisplay();
    //glutTimerFunc(x,doFrame,0);
}

void scene1()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();

    glPushMatrix();
    drawsine();
    glPopMatrix();


    //glScaled(0.3, 0.3, 1);
    object();


    //glutTimerFunc(30,doFrame,0);
    glutSwapBuffers();
}

void exit(void)
{
    exit(-1);
}

void myKeyboard(unsigned char key, int x, int y)
{
    switch (key) {
    case 'h':
    {
        scene1();   }
    break;

    case 'e':
    {
        exit(); }
    break;
    }
}

void display() {

    //glClear(GL_COLOR_BUFFER_BIT);


}

void init() {
    glClearColor(1, 1, 1, 1);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-5, 7, -5, 5, -1, 1);
    glMatrixMode(GL_MODELVIEW);
}


int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE);
    glutInitWindowSize(700, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Roller Coaster Simulation");

    init();

    glutDisplayFunc(display);

    glutTimerFunc(200, doFrame, 0);
    glutKeyboardFunc(myKeyboard);
    glutMainLoop();
    return 0;
}

标签： c++animationopenglglutopengl-compat

解决方案

您必须在显示回调中绘制场景glutDisplayFunc。

添加场景状态（current_scene）并在按键时切换状态：

例如

int current_scene = 1;

void myKeyboard(unsigned char key, int x, int y)
{
   switch (key) {
       case 'h': current_scene = 1; break; 
       case 'i': current_scene = 2; break; 
       // [...]
   }
}

在显示回调中根据状态绘制场景：

void display() {

    glClear(GL_COLOR_BUFFER_BIT);

    switch(current_scene) {
        case 1: scene1(); break;
        case 2: scene2(); break;
        // [...]
    }

    glutSwapBuffers();
    glutPostRedisplay();
}

我建议只做缓冲区交换（glutSwapBuffers）disaply。从其他功能中删除它。
用于glutPostRedisplay将当前窗口标记为需要连续重新显示。

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