/* Animated Parabola and Squares */

// Header files
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>

// Global variables for rotation factors
double spin = 0.0;
double spin2 = 0.0;
int wide=400, high=400;

// This Section creates a Window, but uses only GL commands rather than X.

void myinit()
{
   /* one-time init (clearColor, set palette, etc) */

   glClearColor(1.0, 1.0, 1.0, 1.0 );
   glShadeModel( GL_FLAT );
}



void reshape( int width, int height )  // Essential Magic again!
{
   glViewport(0, 0, (GLint)width, (GLint)height);

   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho( -3.0, 3.0, -3.0, 3.0, -3.0, 3.0 );
   glMatrixMode(GL_MODELVIEW);
}


void babyRectangle()   // Draw rotating red rectangle, offset to edge 
{
   glColor3f(0.8, 0.0, 0.0);
   glPushMatrix();
   glTranslatef(2.0, 2.0, 0.0);
   glRotatef(spin2, 0.0, 0.0, 1.0);
   glRectf(-0.2, -0.2, 0.2, 0.2);
   //glRectf(1.8, 1.8, 2.2, 2.2);
   glPopMatrix();
}

void myRectangle()  // Draw a large Yellow Rectangle and rotate image
{
   glColor3f(1.0, 1.0, 0.0);
   glPushMatrix();
   glRotatef(spin, 0.0, 0.0, 1.0);
   glRectf(-2.0, -2.0, 2.0, 2.0);
   glPopMatrix();
}
void myCube()	// Draw wire frame green cube: Roatate, Translate, Scale
{  static float myscale= 1.0;
   static float step = -0.1;
   glColor3f(0.0, 0.7, 0.0);
   glPushMatrix();
   glRotatef( 10.0, 1.0, 0.0, 1.0);
   glRotatef(spin, 0.0, 1.0, 0.0);
   glTranslatef(0.0, 0.0, -1.0);
   glScalef(myscale, myscale, myscale);
   myscale += step;
   if (myscale <= 0.5) step = 0.05;  // If too small, start growing 
   if (myscale >= 1.5) step = -0.05; // If too big, start shrinking
   glBegin(GL_LINE_STRIP);
     glVertex3f(0.0, 0.0, 0.0);
     glVertex3f(1.0, 0.0, 0.0);
     glVertex3f(1.0, 1.0, 0.0);
     glVertex3f(0.0, 1.0, 0.0);
     glVertex3f(0.0, 0.0, 0.0);
   glEnd();
   glBegin(GL_LINE_STRIP);
     glVertex3f(0.0, 0.0, 1.0);
     glVertex3f(1.0, 0.0, 1.0);
     glVertex3f(1.0, 1.0, 1.0);
     glVertex3f(0.0, 1.0, 1.0);
     glVertex3f(0.0, 0.0, 1.0);
   glEnd();
   glBegin(GL_LINES);
     glVertex3f(0.0, 0.0, 0.0);
     glVertex3f(0.0, 0.0, 1.0);
     glVertex3f(1.0, 1.0, 0.0);
     glVertex3f(1.0, 1.0, 1.0);
     glVertex3f(0.0, 1.0, 0.0);
     glVertex3f(0.0, 1.0, 1.0);
     glVertex3f(1.0, 0.0, 0.0);
     glVertex3f(1.0, 0.0, 1.0);
   glEnd();
   
   glPopMatrix();
}

void DrawMyStuff()  // The Drawing Routine
{float i, j; 
    double x,y, xstep;
    myRectangle();
    babyRectangle();
    myRectangle();
    babyRectangle();
    glColor3f(0.5, 0.5, 1.0);
    glPushMatrix();
    glRotatef(spin, 1.0, 1.0,0.0);
    glBegin( GL_POINTS );
	for (x = -3; x < 3; x += .001) // Step from -1 to +1 inefficiently
          { y = 1 - 2 * x * x;         // Calculate y value of parabola
            glVertex3f(x, y, 0.0);
          }


   glEnd();
   glPopMatrix();
   
   myCube();
} 

void display( )  // Main display routine called from event loop
{  int i;
   /* clear viewport */
   glClear( GL_COLOR_BUFFER_BIT );

 
   /* draw stuff */
   DrawMyStuff();


   /* flush / swap buffers */
   glFlush();
   glutSwapBuffers();
   glutPostRedisplay();
}



void specialKeys(int key, int x, int y)
{
 //  A Function accessing the UP ARROW Key
   switch (key) {
      case GLUT_KEY_UP:
          printf("AUX_UP\n");
          spin -= 2.0;
          if (spin <= 0.0) spin = 360.0;
          spin2 -= 15.0;
          if (spin2 <= 0.0) spin2 += 360.0;
      break;
// A Function accessing the DOWN ARROW Key
      case GLUT_KEY_DOWN:
          printf("AUX_DOWN\n");
          spin += 2.0;
          if (spin >= 360.0) spin = 0;
          spin2 += 15.0;
          if (spin2 >= 360.0) spin2 -= 360.00;
      break;
     }
     display();
}


void keyboard(unsigned char key, int x, int y)  // A Function Accessing the ESCAPE key
{
   switch (key)
   {
     case (unsigned char) 27:  // case '\27' 
        printf("Escape pressed\n");
        exit(0);
     break;
    }
             // If pressed, the window QUITS
}



int main( int argc, char **argv )
{  

   glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB );  // Initialize Display in RGB mode
   glutInitWindowSize(wide, high); 
   glutInitWindowPosition( 50,50 );  // Draw a window starting at (50,50)
                                        // with size of 400 pixels for both
                                        // X and Y dimensions.

   glutCreateWindow("My Window");  // Create window and give it a name.  

   myinit();  // Call Init routine

   //  More Magic

   glutReshapeFunc(reshape);
   glutKeyboardFunc( keyboard );
   glutSpecialFunc( specialKeys );
   glutDisplayFunc(display);

   glutMainLoop( );  

   return 0;
}