#include <GL/glut.h>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <chrono>
#include <thread>
 
// Global variables for stopwatch state
bool stopwatchRunning = false;
std::chrono::steady_clock::time_point startTime;
std::chrono::milliseconds elapsedTime(0);
 
// Function to render text on the screen using bitmap fonts
void renderBitmapString(float x, float y, void *font, const char *string) {
    glRasterPos2f(x, y);
    for (const char *c = string; *c != '\0'; ++c) {
        glutBitmapCharacter(font, *c);
    }
}
 
// Function to display time in HH:MM:SS:MS format
void displayTime() {
    using namespace std::chrono;
 
    // Calculate elapsed time
    auto now = steady_clock::now();
    auto duration = now - startTime + elapsedTime;
 
    // Convert duration to hours, minutes, seconds, and milliseconds
    auto millis = duration_cast<milliseconds>(duration).count() % 1000;
    auto seconds = duration_cast<seconds>(duration).count() % 60;
    auto minutes = duration_cast<minutes>(duration).count() % 60;
    auto hours = duration_cast<hours>(duration).count();
 
    std::ostringstream timeStream;
    timeStream << std::setw(2) << std::setfill('0') << hours << ":"
               << std::setw(2) << std::setfill('0') << minutes << ":"
               << std::setw(2) << std::setfill('0') << seconds << ":"
               << std::setw(3) << std::setfill('0') << millis;
 
    std::string timeString = timeStream.str();
 
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);  // Set the text color to white
 
    // Display student ID
    renderBitmapString(-0.9, 0.9, GLUT_BITMAP_HELVETICA_18, "Student ID: MC123456789");
 
    // Display stopwatch time in the center
    renderBitmapString(-0.2, 0.0, GLUT_BITMAP_HELVETICA_18, timeString.c_str());
 
    glutSwapBuffers();
}
 
// Function to update the display every 10 milliseconds
void update(int value) {
    if (stopwatchRunning) {
        glutPostRedisplay();  // Request a redraw
        glutTimerFunc(10, update, 0);  // Set up the next update
    }
}
 
// Function to handle keyboard input
void keyboard(unsigned char key, int x, int y) {
    if (key == 'S' || key == 's') {
        if (stopwatchRunning) {
            elapsedTime += std::chrono::steady_clock::now() - startTime;
            stopwatchRunning = false;
        } else {
            startTime = std::chrono::steady_clock::now();
            stopwatchRunning = true;
            glutTimerFunc(10, update, 0);  // Start the update loop
        }
    } else if (key == 'R' || key == 'r') {
        stopwatchRunning = false;
        elapsedTime = std::chrono::milliseconds(0);
        glutPostRedisplay();  // Redraw the window
    }
}
 
// Function to initialize OpenGL settings
void init() {
    glClearColor(0.0, 0.0, 0.0, 1.0);  // Set the background color to black
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);  // Set up orthographic projection
    glMatrixMode(GL_MODELVIEW);
}
 
int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(800, 600);
    glutCreateWindow("Digital Stopwatch");
 
    init();
 
    glutDisplayFunc(displayTime);  // Register display function
    glutKeyboardFunc(keyboard);    // Register keyboard function
 
    glutMainLoop();  // Enter the GLUT event processing loop
    return 0;
}
 

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