画出正弦曲线

#include <glut.h>#include <math.h>const int n = 5;const GLfloat R = 0.5f;const GLfloat Pi = 3.1415926536f;const GLfloat factor = 0.05f; void myDisplay(void) {    GLfloat x;     glClear(GL_COLOR_BUFFER_BIT);     glBegin(GL_LINES);     glVertex2f(-1.0f, 0.0f);     glVertex2f(1.0f, 0.0f);     // 以上两个点可以画x轴     glVertex2f(0.0f, -1.0f);     glVertex2f(0.0f, 1.0f);     // 以上两个点可以画y轴     glEnd();     glBegin(GL_LINE_STRIP);     for (x = -1.0f / factor; x < 1.0f / factor; x += 0.01f) {        glVertex2f(x*factor, sin(x)*factor);     }     glEnd();     glFlush(); }int main(int argc, char *argv[]){    glutInit(&argc, argv);    glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);    glutInitWindowPosition(10, 10);    glutInitWindowSize(400, 400);    glutCreateWindow("the first opengl program");    glutDisplayFunc(&myDisplay);    glutMainLoop();    return 0;}