interactive.cpp

#include <GL/glut.h>
#include <math.h>

// Global variables for background color
float red = 1.0, green = 1.0, blue = 1.0;

// Stores mouse position
float mouseX = 0.0, mouseY = 0.0;
int shape = 0; // 1 = Circle, 2 = Square

// Function to draw a circle at (x, y)
void drawCircle(float x, float y, float radius) {
    glBegin(GL_TRIANGLE_FAN);
    glVertex2f(x, y); // Center
    for (int i = 0; i <= 100; i++) {
        float theta = 2.0f * 3.1415926f * float(i) / 100;
        float dx = radius * cos(theta);
        float dy = radius * sin(theta);
        glVertex2f(x + dx, y + dy);
    }
    glEnd();
}

// Function to draw a square at (x, y)
void drawSquare(float x, float y, float size) {
    glBegin(GL_QUADS);
    glVertex2f(x - size, y - size);
    glVertex2f(x + size, y - size);
    glVertex2f(x + size, y + size);
    glVertex2f(x - size, y + size);
    glEnd();
}

// Display function
void display() {
    glClearColor(red, green, blue, 1.0); // Set background color
    glClear(GL_COLOR_BUFFER_BIT);

    // Draw selected shape at mouse position
    if (shape == 1) {
        glColor3f(1.0, 0.0, 0.0); // Red Circle
        drawCircle(mouseX, mouseY, 0.1);
    } else if (shape == 2) {
        glColor3f(0.0, 0.0, 1.0); // Blue Square
        drawSquare(mouseX, mouseY, 0.1);
    }

    glFlush();
}

// Keyboard interaction function
void handleKeypress(unsigned char key, int x, int y) {
    switch (key) {
        case 'r': // Change background to Red
            red = 1.0; green = 0.0; blue = 0.0;
            break;
        case 'g': // Change background to Green
            red = 0.0; green = 1.0; blue = 0.0;
            break;
        case 'b': // Change background to Blue
            red = 0.0; green = 0.0; blue = 1.0;
            break;
        case 27: // Press ESC to exit
            exit(0);
    }
    glutPostRedisplay(); // Update the screen
}

// Mouse interaction function
void handleMouse(int button, int state, int x, int y) {
    if (state == GLUT_DOWN) { // When a button is clicked
        mouseX = (x - 250) / 250.0; // Convert to OpenGL coordinates
        mouseY = -(y - 250) / 250.0; 

        if (button == GLUT_LEFT_BUTTON) {
            shape = 1; // Left Click -> Draw a Circle
        } else if (button == GLUT_RIGHT_BUTTON) {
            shape = 2; // Right Click -> Draw a Square
        } else if (button == GLUT_MIDDLE_BUTTON) {
            shape = 0; // Middle Click -> Clear the shape
        }
    }
    glutPostRedisplay(); // Update the screen
}

// Main function
int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutCreateWindow("Keyboard & Mouse Interaction");

    glClearColor(1.0, 1.0, 1.0, 1.0); // White background
    gluOrtho2D(-1, 1, -1, 1); // Set coordinate system

    glutDisplayFunc(display);
    glutKeyboardFunc(handleKeypress);
    glutMouseFunc(handleMouse);

    glutMainLoop();
    return 0;
}