c# - 未在 cmd 提示符下运行时，OpenGL 未显示正确的输出

Question

我正在尝试为一年级学生编写一个数学教育系统。我的目标是让所有交互都在一个窗口内运行。当我单击第一个窗口(+ 窗口)时，出现的只是黑色窗口，没有任何输出，但在命令提示符下它运行正常。

#include "stdafx.h"
#include <stdlib.h>
#include <iostream>
#include <glut.h>
#include <time.h>

using namespace std;
GLfloat xrot;
GLfloat yrot;
bool mouseDown = false;
bool createWindow = false;

int m=0;
int n=0;
int num1=0;
int num2=0;
int counter=0;

//-------------------------------------------------------------------


void handleKeypress(unsigned char key,int x,int y)
{
    switch(key)
    {
        case 27:
        exit(0);
    }
}

void handleResize(int w,int h)

{

    glViewport(0,0,w,h);

    glMatrixMode(GL_PROJECTION);

    gluPerspective(45.0,(double)w/(double)h,1.0,200);

}

void idle()
{
if (!mouseDown)
{
xrot+= 0.3f;
yrot+= 0.4f;
}

glutPostRedisplay();
}

void drawScene1()

{

    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    glBegin(GL_QUADS);
    glColor3f(1.0,0.0,0.0);
    glVertex3f(-1.0f,5.0f,-20.0f);
    glVertex3f(-1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,5.0f,-20.0f);
    glEnd();

    glRotatef(90.0,0.0f,0.0f,1.0f);

    glBegin(GL_QUADS);
    glColor3f(1.0,0.0,0.0);
    glVertex3f(-1.0f,5.0f,-20.0f);
    glVertex3f(-1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,5.0f,-20.0f);
    glutSwapBuffers();


}

void drawScene2()

{

    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    glRotatef(90.0,0.0f,0.0f,1.0f);

    glBegin(GL_QUADS);
    glColor3f(0.0,0.0,1.0);
    glVertex3f(-1.0f,5.0f,-20.0f);
    glVertex3f(-1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,-5.0f,-20.0f);
    glVertex3f(1.0f,5.0f,-20.0f);
    glEnd();

    glutSwapBuffers();
}

void myInit(void)
{
glEnable(GL_DEPTH_TEST);
glClearColor(1.0, 1.0, 1.0, 0.0); // set the background to white
glColor3f(0.0, 0.0, 0.0);
// set the drawing color to black

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1000.0,1000.0,-1000.0,1000.0,-100.0,100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

}
//------------------------------------------------------

void triangle()
{
    glBegin(GL_TRIANGLES);
    glColor3f(1.0f,0.0f,0.0f);
    glVertex3f(0.0f,100.0f,0.0f);
    glVertex3f(100.0f,-100.0f,0.0f);
    glVertex3f(-100.0f,-100.0f,0.0f);
    glEnd();
}

void minus()
{
    glPushMatrix();
    glBegin(GL_QUADS);
    glColor3f(0.0f,1.0f,0.0f);
    glVertex3f(-200.0f,50.0f,0.0f);
    glVertex3f(-200.0f,-50.0f,0.0f);
    glVertex3f(200.0f,-50.0f,0.0f);
    glVertex3f(200.0f,50.0f,0.0f);
    glEnd();
    glPopMatrix();
}

void myDisplay(void)
{

// Clear Color and Depth Buffers
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Reset transformations
    glLoadIdentity();

    // Set the camera
    gluLookAt(0, 0, 3, 0 , 0 , 0 , 0.0f,1.0f,0.0f);

    //Generate random number 
    srand (time(NULL));
    num1 = rand() % 10 +1; 
    num2 = rand() % 10 +1;
    if(num1 < num2){
    int temp = num1;
    num1 = num2;
    num2 = temp;
    }

    //rows and column
    m = 2;   //row
    n = 5;   //column

    counter=0; //make sure it zero

    //First Number to be draw
    glPushMatrix(); //set as origin
    glTranslatef( -700.0,700, 0 ); //translate
    //draw
    for(int i = 0; i < m; i++){ //row
        for(int j=0; j < n; j++) { //column
            if(counter>=num1) break; //a=how many triangle need to draw; s=already draw how many triangle; 
            glPushMatrix(); //set transformation
            glTranslatef( i*200.0 ,j*-200.0, 0 ); //translate
            triangle(); //draw triangle
            glPopMatrix(); //reset transformation
            counter++; //counter s
        }
    }
    glPopMatrix(); //reset transformation

    //create plus sign
    glPushMatrix(); //set transformation or object position/orientation/scale for reset
    glTranslatef( 0.0,400, 0 );
    minus();
    glPopMatrix(); //reset transformation to origin

    counter=0; //reset counter
    //Second number to be draw
    glPushMatrix();
    glTranslatef( 500.0,700, 0 );
    for(int i = 0; i < m; i++){
        for(int j=0; j < n; j++) {
            if(counter>=num2) break;
            glPushMatrix();
            glTranslatef( i*200.0 ,j*-200.0, 0 );
            triangle();
            glPopMatrix();
            counter++;
        }
    }
    glPopMatrix();

    //Control
    glutSwapBuffers();//take the drawing to the screen

    //check answer
    /*cout<<num1<<endl; //debug
    cout<<num2<<endl;*/

    int check=0;
    int answer=0;
    cout << "Answer ???"<<endl;
    cin >> answer;
    while(true){
        check=num1-num2;
        if(answer==check){
            cout << "CORRECT!!!"<<endl;
            break;
        } else{
            cout << "TRY AGAIN!!!";
            cout << "Answer ???"<<endl;
            cin >> answer;
        }
    }
}



void mouse (int button, int state, int x, int y){
    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN){
    myInit();
    triangle();
    minus();
    myDisplay();
    }
}


int main(int argc,char** argv)

{

    glutInit(&argc,argv);

    myInit();

    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

    glutInitWindowSize(500,500);


    //window1=

     glutCreateWindow("First window");

    glutDisplayFunc(drawScene1);

    glutKeyboardFunc(handleKeypress);

    glutReshapeFunc(handleResize);
    glutMouseFunc(mouse);

    //create the second  window

    //window2 =

    glutCreateWindow("Second Window");

    //define a window position for second window

    glutPositionWindow(540,40);

    // register callbacks for second window, which is now current

    glutReshapeFunc(handleResize);

    glutDisplayFunc(drawScene2);

    glutKeyboardFunc(handleKeypress);
    glutMouseFunc(mouse);

    glutMainLoop();





    return 0;


}

Answer 1

您将 stdio(即控制台输入/输出)与窗口系统事件处理混合在一起。这是问题的秘诀。 stdio 操作阻塞，直到它们完成。在从 cin 读取的情况下，进程将阻塞，等待来自控制台的输入，直到输入换行符。在此期间，不会处理任何窗口事件，也不会向 OpenGL 窗口绘制任何内容。

简而言之，您不能像以前那样将两者混为一谈。您可以很好地使用输出(cout 和 cerr)，如果没有连接控制台，它们将写入 NIL，但尝试读取某些内容会无限期地阻塞。您必须考虑 stdio 以外的其他方式来与事件交互程序中的用户进行交互。 IE。您必须在键盘回调中处理按键事件。