sam.cpp

#include <GL/glut.h>

float red = 1.0f, green = 0.0f, blue = 0.0f;  // Initial color is red


void display() {
    glClear(GL_COLOR_BUFFER_BIT);

    glColor3f(red, green, blue);

    glBegin(GL_TRIANGLES);
        glVertex2f(-0.5f, -0.5f);
        glVertex2f( 0.5f, -0.5f);
        glVertex2f( 0.0f,  0.5f);
    glEnd();


    glutSwapBuffers();
}
void keyboard(unsigned char key, int x, int y) {
    if (key == '1') {
       
        red = 0.0f;
        green = 1.0f;
        blue = 0.0f;
    }
    else if (key == '2') {
       
        red = 0.0f;
        green = 0.0f;
        blue = 1.0f;
    }
    else if (key == 'r' || key == 'R') {
       
        red = 1.0f;
        green = 0.0f;
        blue = 0.0f;
    }

   
    glutPostRedisplay();
}

int main(int argc, char** argv) {
 
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

    glutInitWindowSize(800, 600);

    glutCreateWindow("OpenGL Triangle Color Change");

     glutDisplayFunc(display);

    glutKeyboardFunc(keyboard);

    glutMainLoop();

    return 0;
}