/*
 * Copyright (c) 1996-1999  Silicon Graphics, Inc.  All rights reserved.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF THE
 * POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* perspective.c - open a window and clear the background.
 *	Set up callbacks to handle keyboard input.
 *  	Model some objects.  Use perspective projection.
 *
 *	F1 key			- print help information
 *	SPACE key		- generates a random background color
 *	<s> key			- toggle smooth/flat shading
 *	Escape Key		- exit program
 */
#include <GL/glut.h>	/* includes gl.h, glu.h */

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

#include "checkerror.h"
#include "random.h"

/* Function Prototypes */

GLvoid initgfx( GLvoid );
GLvoid keyboard( GLubyte, GLint, GLint );
GLvoid specialkeys( GLint, GLint, GLint );
GLvoid drawScene( GLvoid );

void printHelp( char * );

/* Global Variables */

static char *progname; 

/* Global Definitions */

#define KEY_ESC	27	/* ascii value for the escape key */

void
main( int argc, char *argv[] )
{
	GLsizei width, height;

	glutInit( &argc, argv );

	/* create a window that is 1/4 the size of the screen,
	 * and position it in the middle of the screen.
	 */
	width = glutGet( GLUT_SCREEN_WIDTH ); 
	height = glutGet( GLUT_SCREEN_HEIGHT );
	glutInitWindowPosition( width / 4, height / 4 );
	glutInitWindowSize( width / 2, height / 2 );
	glutInitDisplayMode( GLUT_RGBA );
	glutCreateWindow( argv[0] );

	initgfx();

	glutKeyboardFunc( keyboard );
	glutSpecialFunc( specialkeys );
	glutDisplayFunc( drawScene ); 

	progname = argv[0];

	printHelp( progname );

	glutMainLoop();
}

void
printHelp( char *progname )
{
	fprintf(stdout, 
		"\n%s - model some objects using a perspective projection\n\n"
		"F1 key		- print help information\n"
		"SPACE Key	- generates a random background color\n"
		"<s> key		- toggle smooth/flat shading\n"
		"Escape Key	- exit the program\n\n",
		progname);
}

GLvoid
initgfx( GLvoid )
{
	/* set clear color to blue */
	glClearColor( 0.0f, 0.0f, 1.0f, 1.0f );

	glMatrixMode( GL_PROJECTION );
	gluPerspective( 45.0f, 1.0f, 3.0f, 7.0f );
	glMatrixMode( GL_MODELVIEW );
}

GLvoid 
keyboard( GLubyte key, GLint x, GLint y )
{
	static GLboolean flat = GL_FALSE;

	switch (key) {
	case ' ':	/* SPACE key */
		/* generate a random background color */
		glClearColor( RANDOM(), RANDOM(), RANDOM(), 1.0f ); 
		glutPostRedisplay();
		break;
	case 's':	/* s key */
		/* toggle between smooth and flat shading */
		flat = !flat;
		if (flat)
			glShadeModel( GL_FLAT );
		else 
			glShadeModel( GL_SMOOTH );
		glutPostRedisplay();
		break;
	case KEY_ESC:	/* Exit when the Escape key is pressed */
		exit(0);
	}
}

GLvoid 
specialkeys( GLint key, GLint x, GLint y )
{
	switch (key) {
	case GLUT_KEY_F1:	/* Function key #1 */
		/* print help information */
		printHelp( progname );
		break;
	}
}

GLvoid
drawScene( GLvoid )
{
	static GLfloat red[] = { 1.0f, 0.0f, 0.0f };
	static GLfloat yellow[] = { 1.0f, 1.0f, 0.0f };
	static GLfloat blue[] = { 0.0f, 0.0f, 1.0f };
	static GLfloat green[] = { 0.0f, 1.0f, 0.0f };
	static GLfloat darkgreen[] = { 0.0f, 0.25f, 0.0f };

	/* left window */
	static GLfloat v0[] = { -0.4f, 0.8f };
	static GLfloat v1[] = { -0.4f, 0.4f };
	static GLfloat v2[] = { -0.3f, 0.8f };
	static GLfloat v3[] = { -0.3f, 0.4f };
	static GLfloat v4[] = { -0.2f, 0.8f };
	static GLfloat v5[] = { -0.2f, 0.4f };

	/* right window */
	static GLfloat v6[] = { 0.2f, 0.8f };
	static GLfloat v7[] = { 0.2f, 0.4f };
	static GLfloat v8[] = { 0.3f, 0.8f };
	static GLfloat v9[] = { 0.3f, 0.4f };
	static GLfloat v10[] = { 0.4f, 0.8f };
	static GLfloat v11[] = { 0.4f, 0.4f };

	glClear( GL_COLOR_BUFFER_BIT );

	glPushMatrix();

	/* move inside the viewing volume */
	glTranslatef( 0.0f, 0.0f, -4.0f );

	/* draw the ground in different shades of green */
	glBegin( GL_POLYGON );
		glColor3fv( green );
		glVertex2f( -2.0f, -2.0f );
		glVertex2f( 2.0f, -2.0f );
		glColor3fv( darkgreen );
		glVertex2f( 2.0f, 0.0f );
		glVertex2f( -2.0f, 0.0f );
	glEnd();

	/* draw the house */
	glColor3f( 1.0f, 1.0f, 1.0f ); /* white */
	glRectf( -0.5f, -0.5f, 0.5f, 1.0f );

	/* draw the door */
	glColor3f( 0.5f, 0.2f, 0.1f ); /* brown */
	glRectf( -0.2f, -0.5f, 0.2f, 0.2f );

	/* draw the roof */
	glBegin( GL_TRIANGLES );
		glColor3f( 0.0f, 0.0f, 0.0f ); /* black */
		glVertex2f( -0.5f, 1.0f );
		glVertex2f( 0.5f, 1.0f );
		glVertex2f( 0.0f, 1.5f );
	glEnd();

	/* draw 2 quadrilateral strip to make a window */
	glBegin( GL_QUAD_STRIP );
		glColor3f( 1.0f, 0.0f, 0.0f );
		glVertex2fv (v0);
		glColor3f( 0.9f, 0.0f, 1.0f );
		glVertex2fv (v1);
		glColor3f( 0.8f, 0.1f, 0.0f );
		glVertex2fv (v2);
		glColor3f( 0.7f, 0.2f, 1.0f );
		glVertex2fv (v3);
		glColor3f( 0.6f, 0.3f, 0.0f );
		glVertex2fv (v4);
		glColor3f( 0.5f, 0.4f, 1.0f );
		glVertex2fv (v5);
		glColor3f( 0.4f, 0.5f, 0.0f );
	glEnd();

	/* draw 2 quadrilateral strip to make a window */
	glBegin( GL_QUAD_STRIP );
		glVertex2fv (v6);
		glColor3f( 0.3f, 0.6f, 1.0f );
		glVertex2fv (v7);
		glColor3f( 0.2f, 0.7f, 0.0f );
		glVertex2fv (v8);
		glColor3f( 0.1f, 0.8f, 1.0f );
		glVertex2fv (v9);
		glColor3f( 0.0f, 0.9f, 0.0f );
		glVertex2fv (v10);
		glColor3f( 0.0f, 1.0f, 1.0f );
		glVertex2fv (v11);
	glEnd();

	/* Draw a triangle fan for the sun */
	glBegin( GL_TRIANGLE_FAN );
	  glColor3f( 1.0f, 1.0f, 1.0f );
	  glVertex2f( 1.5f, 1.5f );
	  glColor3fv( yellow );
	  glVertex2f( 1.5f, 1.3f );
	  glVertex2f( 1.7f, 1.4f );
	  glVertex2f( 1.7f, 1.6f );
	  glVertex2f( 1.5f, 1.7f );
	  glVertex2f( 1.3f, 1.6f );
	  glVertex2f( 1.3f, 1.4f );
	  glVertex2f( 1.5f, 1.3f );
	glEnd();

	/* draw a flower in the foreground */

	glTranslatef( 1.0f, -1.0f, 1.0f );

	/* draw the stem with 2 leaves */

	glColor3fv( darkgreen );
	glBegin( GL_LINES );
		glVertex2f( 0.0f, 0.0f );		 /* stem */
		glVertex2f( 0.0f, 0.25f );
		glVertex2f( 0.0f, 0.1f );		 /* leaf */
		glVertex2f( 0.05f, 0.15f ); 
		glVertex2f( 0.0f, 0.05f );	 /* leaf */
		glVertex2f( -0.05f, 0.2f );
	glEnd();

	/* move to the top of the stem */

	glTranslatef( 0.0f, 0.25f, 0.0f );

	/* use a triangle fan for the flower head */

	glBegin( GL_TRIANGLE_FAN );
	  glColor3f( 1.0f, 1.0f, 1.0f );
	  glVertex2f( 0.0f, 0.0f );
	  glColor3f( 1.0f, 0.0f, 0.0f );
	  glVertex2f( 0.0f, -0.03f );
	  glVertex2f( 0.03f, -0.02f );
	  glVertex2f( 0.03f, 0.02f );
	  glVertex2f( 0.0f, 0.03f );
	  glVertex2f( -0.03f, 0.02f );
	  glVertex2f( -0.03f, -0.02f );
	  glVertex2f( 0.0f, -0.03f );
	glEnd();

	glPopMatrix();

	checkError( "drawScene" );
	glFlush();
}