OpenGL Bresenham Line

У меня есть базовый код для рисования линии Брезенхема с использованием opengl. Проблема в том, что в конце он не показывает результаты. Только окно открывается и закрывается быстро без каких-либо других ошибок. Кто-нибудь может мне помочь?

#include <math.h>
#include <iostream>
#include <algorithm>
#include <GL\glew.h>
#include <GL\freeglut.h>

int ww = 600, wh = 400;
int xi, yi, xf, yf;
bool firstClick = true;

using namespace std;

void setPixel(int x, int y)
{
glColor3f(0.0, 0.0, 0.0); //Set pixel to black
glBegin(GL_POINTS);
glVertex2i(x, y); //Set pixel coordinates
glEnd();
glFlush(); //Render pixel
}

//Draw line if X distance is greater than Y
void bresenhamX(int x0, int y0, int x1, int y1, int dx, int dy)
{
int i, j, k;

i = 2 * dy - dx;
j = 2 * dy;
k = 2 * (dy - dx);
if (!(x0 < x1)) {
swap(x0, x1);
swap(y0, y1);
}
setPixel(x0, y0);
while (x0 < x1) {
if (i < 0)
i += j;
else {
if (y0 < y1)
++y0;
else
--y0;
i += k;
}
++x0;
setPixel(x0, y0);
}
}

//Draw line if X distance is lesser than Y
void bresenhamY(int x0, int y0, int x1, int y1, int dx, int dy)
{
int i, j, k;

i = 2 * dx - dy;
j = 2 * dx;
k = 2 * (dx - dy);
if (!(y0 < y1)) {
swap(x0, x1);
swap(y0, y1);
}
setPixel(x0, y0);
while (y0 < y1) {
if (i < 0)
i += j;
else {
if (x0 > x1)
--x0;
else
++x0;
i += k;
}
++y0;
setPixel(x0, y0);
}
}

//Called by mouse(), will call the appropriate function depending on the length of the X and Y axis
void bresenham(int x0, int y0, int x1, int y1)
{
int dx = abs(x1 - x0);
int dy = abs(y1 - y0);

if (dx >= dy)
bresenhamX(x0, y0, x1, y1, dx, dy);
else
bresenhamY(x0, y0, x1, y1, dx, dy);
}

//Calls Bresenham function when the mouse has traced a line
void mouse(int btn, int state, int x, int y)
{
if (btn == GLUT_LEFT_BUTTON) {
if (firstClick) {
xi = x;
yi = (wh - y);
firstClick = false;
}
else {
xf = x;
yf = (wh - y);
bresenham(xi, yi, xf, yf);
firstClick = true;
}
}
}

// Keyboard input processing routine.
void keyInput(unsigned char key, int x, int y)
{
switch (key)
{
case 27: // Press escape to exit.
exit(0);
break;
default:
break;
}
}

// Drawing (display) routine.
void drawScene(void)
{
glClearColor(0.4, 0.7, 0.5, 1.0); // Set foreground color
glColor3f(0.2, 0.3, 0.3); // Clear screen to background color.
glClear(GL_COLOR_BUFFER_BIT);   //Flush created objects to the screen, i.e., force rendering.
glFlush();
}

// OpenGL window reshape routine.
void setup()
{
glViewport(0, 0, ww, wh); // Set viewport size to be entire OpenGL window.
glMatrixMode(GL_PROJECTION); // Set matrix mode to projection.
glLoadIdentity(); // Clear current projection matrix to identity.
gluOrtho2D(0.0, (GLdouble)ww, 0.0, (GLdouble)wh); // Specify the orthographic (or perpendicular) projection, i.e., define the viewing box.
glMatrixMode(GL_MODELVIEW); // Set matrix mode to modelview.
}

// Main routine: defines window properties, creates window, registers callback routines and begins processing.
int main(int argc, char **argv)
{
glutInit(&argc, argv); // Initialize GLUT.
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); // Set display mode as single-buffered and RGB color.
glutInitWindowSize(ww, wh); // Set OpenGL window size.
glutInitWindowPosition(100, 100); // Set position of OpenGL window upper-left corner.
glutCreateWindow("Bresenham"); // Create OpenGL window with title.
glutDisplayFunc(drawScene); // Register display routine.
setup(); // Register reshape routine.
glutKeyboardFunc(keyInput); // Register keyboard routine.
glutMouseFunc(mouse); // Begin processing.
glutMainLoop();
return 0;
}