torus.cpp

// This is a simple introductory program; its main window contains a static
// picture of a torus.  The program illustrates viewing by choosing a camera
// setup with gluLookAt(), which is conceptually simpler than transforming
// objects to move into a predefined view volume.

#ifdef __APPLE_CC__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

// Clears the window and draws the torus.
void display() {

  glClear(GL_COLOR_BUFFER_BIT);

  // Draw a white torus of outer radius 3, inner radius 0.5 with 15 stacks
  // and 30 slices.
  glColor3f(1.0, 1.0, 1.0);
  glutWireTorus(0.5, 3, 15, 30);

  // Draw a red x-axis, a green y-axis, and a blue z-axis.  Each of the
  // axes are ten units long.
  glBegin(GL_LINES);
    glColor3f(1, 0, 0); glVertex3f(0, 0, 0); glVertex3f(10, 0, 0);
    glColor3f(0, 1, 0); glVertex3f(0, 0, 0); glVertex3f(0, 10, 0);
    glColor3f(0, 0, 1); glVertex3f(0, 0, 0); glVertex3f(0, 0, 10);
  glEnd();

  glFlush();
}

// Sets up global attributes like clear color and drawing color, and sets up
// the desired projection and modelview matrices.
void init() {

  // Set the current clear color to black and the current drawing color to
  // white.
  glClearColor(0.0, 0.0, 0.0, 1.0);
  glColor3f(1.0, 1.0, 1.0);

  // Set the camera lens to have a 60 degree (vertical) field of view, an
  // aspect ratio of 4/3, and have everything closer than 1 unit to the
  // camera and greater than 40 units distant clipped away.
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(60.0, 4.0/3.0, 1, 40);

  // Position camera at (4, 6, 5) looking at (0, 0, 0) with the vector
  // <0, 1, 0> pointing upward.
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(4, 6, 5, 0, 0, 0, 0, 1, 0);
}

// Initializes GLUT, the display mode, and main window; registers callbacks;
// does application initialization; enters the main event loop.
int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowPosition(80, 80);
  glutInitWindowSize(800, 600);
  glutCreateWindow("A Simple Torus");
  glutDisplayFunc(display);
  init();
  glutMainLoop();
}