/* prac4b.c  */


/* 
	Purpose: This program constructs a cube, and uses function keys
   to control translation, rotation and scaling of the shape. 
*/

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

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define KEY_ESC 27      /* glut doesn't define this one */


/* Global Constants */

static const float v0[3] = {0.0,0.0,0.0};
static const float v1[3] = {1.0,0.0,0.0};
static const float v2[3] = {1.0,1.0,0.0};
static const float v3[3] = {0.0,1.0,0.0};
static const float v4[3] = {0.0,0.0,1.0};
static const float v5[3] = {1.0,0.0,1.0};
static const float v6[3] = {1.0,1.0,1.0};
static const float v7[3] = {0.0,1.0,1.0};


/*  Functions  */

void printHelp( void )
{
	fprintf(stdout,
		"\nCube Transformations\n\n"
                "Escape key - exit the program\n\n");
}

GLvoid keyboard( GLubyte key, GLint x, GLint y)
{
    switch (key) 
	{
    case KEY_ESC:   /* exit when escape key is pressed */
         exit(0);
    }
}

GLvoid specialkeys( GLint key, GLint x, GLint y)
{
    switch (key) 
	{
    case GLUT_KEY_F1:   /* print Help information */
        printHelp ( );
        break;
    }
}

GLvoid checkError( const char* const label )
{
	GLenum error;

	error = glGetError();
	while ( GL_NO_ERROR != error )
	{
		fprintf( stderr,"%s: %s\n", label, gluErrorString(error) );
		error = glGetError();
	}
}

GLvoid drawCube( GLvoid )
{
	glBegin(GL_LINE_LOOP);
	/* Front face of cube */
	  glVertex3fv(v0);
	  glVertex3fv(v1);
	  glVertex3fv(v2);
	  glVertex3fv(v3);
	glEnd();

	glBegin(GL_LINE_LOOP);
	/* Back face of cube */
	  glVertex3fv(v4);
	  glVertex3fv(v5);
	  glVertex3fv(v6);
	  glVertex3fv(v7);
	glEnd();

	glBegin(GL_LINES);
	  /* join front frame to back frame: */
	  glVertex3fv(v0);
	  glVertex3fv(v4);
	  glVertex3fv(v1);
	  glVertex3fv(v5);
	  glVertex3fv(v3);
	  glVertex3fv(v7);
	  glVertex3fv(v2);
	  glVertex3fv(v6);
	glEnd();
}

GLvoid display( GLvoid )
{
	GLfloat ww;
	GLfloat wh;

	glClear( GL_COLOR_BUFFER_BIT );
	/* Do all your OpenGL rendering here */


	/* Get current window size */
	ww = glutGet(GLUT_WINDOW_WIDTH);
	wh = glutGet(GLUT_WINDOW_HEIGHT);

	/* First viewport: */
	glViewport(0,wh/2,ww/2,wh/2);
	glScalef(1.25,1.0,1.0);
	glRotatef(30,1,0,0);
	glRotatef(85,0,1,0);
	drawCube();

	/* 2nd Viewport: */
	glViewport(ww/2,wh/2,ww/2,wh/2);
	/* Need to undo previous transformations */
	glRotatef(-85,0,1,0);
	glRotatef(-30,1,0,0);
	glScalef(4/5.0,1,1);
	/* New transformations: */
	glTranslatef(0,0,0.5);
	glRotatef(60,0,0,1);
	glRotatef(45,0,1,0);
	glRotatef(-30,1,0,0);
	drawCube();

	/* 3rd Viewport: */
	glViewport(0,0,ww/2,wh/2);
	/* undo previous transformations */
	glRotatef(30,1,0,0);
	glRotatef(-45,0,1,0);
	glRotatef(-60,0,0,1);
	glTranslatef(0,0,-0.5);

	/* New transformations: */
	glScalef(1.0,2.0,1.5);
	glTranslatef(0,0.5,0);
	glRotatef(-35,0,0,1);
	glRotatef(65,1,0,0);
	glRotatef(20,0,1,0);
	drawCube(); 

	/* 4th Viewport: */
	glViewport(ww/2,0,ww/2,wh/2);
	/* undo previous transformations */
	glRotatef(-20,0,1,0);
	glRotatef(-65,1,0,0);
	glRotatef(35,0,0,1);
	glTranslatef(0,-0.5,0);
	glScalef(1,0.5,2/3.0);

	/* New transformations: */
	glRotatef(45,0,1,0);
	glRotatef(30,0,0,1);
	drawCube();

	checkError( "display" );
	glFlush();
}

GLvoid init( GLvoid )
{
        glClearColor( 1.0, 1.0, 1.0, 1.0);

		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		glOrtho(-2.0, 2.0, -2.0, 2.0, -2.0, 2.0);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();

		glColor3f(1.0,0.0,0.0);
		glLineWidth(3.0);
}


int main( int argc, char *argv[] )
{
	glutInit( &argc, argv );

	glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
	glutCreateWindow( argv[0] );

	init();
      
	glutKeyboardFunc( keyboard );
	glutSpecialFunc( specialkeys );
	glutDisplayFunc( display ); 

	printHelp( );

	glutMainLoop();

	return 0;
}