/*
 * 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.
 */

/* background.c - open a window and clear the background.
 *   glutMainLoop() calls drawScene whenever the window needs
 *   to be updated.
 */
#include <GL/glut.h>	/* includes gl.h, glu.h */

#include <stdio.h>

/* Function Prototypes */
GLvoid initgfx( GLvoid );
GLvoid drawScene( GLvoid );
void checkError( char * );


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

	/* Le seguenti variabili sono utilizzate per mostrare il numero
       di bit (bitplane) per colore */
	GLint redplanes, greenplanes, blueplanes, alphaplanes; 

	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] );

	/* Verifichiamo il numero di bitplane della finestra
	   appena definita */
	glGetIntegerv( GL_RED_BITS, &redplanes ); 
	glGetIntegerv( GL_GREEN_BITS, &greenplanes ); 
	glGetIntegerv( GL_BLUE_BITS, &blueplanes ); 
	glGetIntegerv( GL_ALPHA_BITS, &alphaplanes );	
	printf("bitplane per colore: R->%d G->%d B->%d A->%d\n",
	        redplanes,greenplanes,blueplanes,alphaplanes);

	initgfx();

	glutDisplayFunc( drawScene ); 
	glutMainLoop();
}

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

void 
checkError( char *label )
{
	GLenum error;
	while ( (error = glGetError()) != GL_NO_ERROR )
		printf( "%s: %s\n", label, gluErrorString(error) );
}


GLvoid
drawScene( GLvoid )
{
	glClear( GL_COLOR_BUFFER_BIT );

	/* Do all your OpenGL rendering here */

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