// Programmer: Mihalis Tsoukalos
// Date: Wednesday 04 June 2014
//
// A simple OpenGL program that draws a triangle
// and automatically rotates it.
//
// g++ rotateCube.cc -lm -lglut -lGL -lGLU -o rotateCube
#include <iostream>
#include <stdlib.h>
// the GLUT and OpenGL libraries have to be linked correctly
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
using namespace std;
// The coordinates for the vertices of the cube
double x = 0.6;
double y = 0.6;
double z = 0.6;
float angle = 0.0;
void drawCube()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset transformations
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -5.0);
// Add an ambient light
GLfloat ambientColor[] = {0.2, 0.2, 0.2, 1.0};
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientColor);
// Add a positioned light
GLfloat lightColor0[] = {0.5, 0.5, 0.5, 1.0};
GLfloat lightPos0[] = {4.0, 0.0, 8.0, 1.0};
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColor0);
glLightfv(GL_LIGHT0, GL_POSITION, lightPos0);
glTranslatef(0.5, 1.0, 0.0);
glRotatef(angle, 1.0, 1.0, 1.0);
glRotatef( angle, 1.0, 0.0, 1.0 );
glRotatef( angle, 0.0, 1.0, 1.0 );
glTranslatef(-0.5, -1.0, 0.0);
// Create the 3D cube
// BACK
glBegin(GL_POLYGON);
glColor3f(0.5, 0.3, 0.2);
glVertex3f(x, -y, z);
glVertex3f(x, y, z);
glVertex3f(-x, y, z);
glVertex3f(-x, -y, z);
glEnd();
// FRONT
glBegin(GL_POLYGON);
glColor3f(0.0, 0.5, 0.0);
glVertex3f(-x, y, -z);
glVertex3f(-x, -y, -z);
glVertex3f(x, -y, -z);
glVertex3f(x, y, -z);
glEnd();
// LEFT
glBegin(GL_POLYGON);
glColor3f(0.5, 0.5, 0.5);
glVertex3f(-x, -y, -z);
glVertex3f(-x, -y, z);
glVertex3f(-x, y, z);
glVertex3f(-x, y, -z);
glEnd();
// RIGHT
glBegin(GL_POLYGON);
glColor3f(0.0, 0.0, 0.0);
glVertex3f(x, -y, -z);
glVertex3f(x, -y, z);
glVertex3f(x, y, z);
glVertex3f(x, y, -z);
glEnd();
// TOP
glBegin(GL_POLYGON);
glColor3f(0.6, 0.0, 0.0);
glVertex3f(x, y, z);
glVertex3f(-x, y, z);
glVertex3f(-x, y, -z);
glVertex3f(x, y, -z);
glEnd();
// BOTTOM
glBegin(GL_POLYGON);
glColor3f(0.3, 0.0, 0.3);
glVertex3f(-x, -y, -z);
glVertex3f(-x, -y, z);
glVertex3f(x, -y, z);
glVertex3f(x, -y, -z);
glEnd();
glFlush();
glutSwapBuffers();
}
// Function for increasing the angle variable smoothly,
// keeps it <=360
// It can also be implemented using the modulo operator.
void update(int value)
{
angle += 1.0f;
if (angle > 360)
{
angle -= 360;
}
glutPostRedisplay();
glutTimerFunc(25, update, 0);
}
// Initializes 3D rendering
void initRendering()
{
glEnable(GL_DEPTH_TEST);
glEnable(GL_COLOR_MATERIAL);
// Set the color of the background
glClearColor(0.7f, 0.8f, 1.0f, 1.0f);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_NORMALIZE);
}
// Called when the window is resized
void handleResize(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (double)w / (double)h, 1.0, 200.0);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(700, 700);
glutInitWindowPosition(100, 100);
glutCreateWindow("OpenGL - Rotating a Cube");
initRendering();
glutDisplayFunc(drawCube);
glutReshapeFunc(handleResize);
// Add a timer for the update(...) function
glutTimerFunc(25, update, 0);
glutMainLoop();
return 0;
}
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