[SuperBible Code] Different result from the sample

Hi all, I am new on OpenGL, and reading ‘OpenGL Super Bible 4th’ now.

In the chapter 2 (Page 54), I run the sample code, but I got different result from the book. Actually I didn’t get rectangle.

The source code like this:


#include "gltools.h"
#include "math3d.h"

void RenderScene(void)
{
  // Clear the window with current clearing color
  glClear(GL_COLOR_BUFFER_BIT);
  // Set current drawing color to red
  //         R     G     B
  glColor3f(1.0f, 0.0f, 0.0f);
  // Draw a filled rectangle with current color
  glRectf(-25.0f, 25.0f, 25.0f, -25.0f);
  // Flush drawing commands
  glFlush();
}


///////////////////////////////////////////////////////////
// Set up the rendering state
void SetupRC(void)
{
  // Set clear color to blue
  glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
}


///////////////////////////////////////////////////////////
// Called by GLUT library when the window has chanaged size
void ChangeSize(GLsizei w, GLsizei h)
{
  GLfloat aspectRatio;
  // Prevent a divide by zero
  if(h == 0)
  h = 1;
  // Set Viewport to window dimensions
  glViewport(0, 0, w, h);
  // Reset coordinate system
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  CHAPTER 2 Using OpenGL 54LISTING 2.2 Continued
  // Establish clipping volume (left, right, bottom, top, near, far)
  aspectRatio = (GLfloat)w / (GLfloat)h;
  
  if (w <= h)
    glOrtho (-100.0, 100.0, -100 / aspectRatio, 100.0 / aspectRatio, 1.0, -1.0);

  else
    glOrtho (-100.0 * aspectRatio, 100.0 * aspectRatio,
-100.0, 100.0, 1.0, -1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}


///////////////////////////////////////////////////////////
// Main program entry point
void main(void)
int main(int argc, char* argv[])
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutCreateWindow(“GLRect”);
  glutDisplayFunc(RenderScene);
  glutReshapeFunc(ChangeSize);
  SetupRC();
  glutMainLoop();
  return 0;
}

The function of the program is to draw a rectangle.

Is the code wrong?