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;
}