/*
 * 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.
 */

/* colorMaterial.c - demonstrates using glColorMaterial to quickly 
 *		change material properties.
 *
 *	Escape key			- exit the program
 */
#include <GL/glut.h>	/* includes gl.h, glu.h */

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

/*  Function Prototypes  */

GLvoid  initgfx( GLvoid );
GLvoid  drawScene( GLvoid );
GLvoid  reshape( GLsizei, GLsizei );
GLvoid  keyboard( GLubyte, GLint, GLint );

void resetView( GLvoid );
void polarView( GLfloat, GLfloat, GLfloat, GLfloat );
void printHelp( char * );

/* Global Definitions */

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

/* Global Variables */

static GLdouble		fovy, nearClip, farClip; 
static GLfloat		distance, twistAngle, incAngle, azimAngle;

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

	glutInit( &argc, argv );

	width = glutGet( GLUT_SCREEN_WIDTH ); 
	height = glutGet( GLUT_SCREEN_HEIGHT );
	glutInitWindowPosition( width / 4, height / 4 );
	glutInitWindowSize( (width / 2) - 4, height / 2 );
	glutInitDisplayMode( GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE );
	glutCreateWindow( argv[0] );

	initgfx();

	glutKeyboardFunc( keyboard );
	glutReshapeFunc( reshape );
	glutDisplayFunc( drawScene ); 

	printHelp( argv[0] );

	glutMainLoop();
}

void
printHelp( char *progname )
{
	fprintf(stdout, "\n%s - demonstrate fast material changes\n\n"
		"Escape key		- exit the program\n\n", progname);
}

GLvoid
initgfx( GLvoid )
{
	GLfloat mat_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
	GLfloat mat_shininess[] = { 10.0f };

	glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
	glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);

	/* changing AMBIENT and DIFFUSE properties to the same value
	 * for the front face only
	 */
	glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
	glEnable(GL_COLOR_MATERIAL);
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);

	glClearColor( 0.0, 0.0, 0.0, 1.0 );
	glEnable( GL_DEPTH_TEST );

	fovy = 60.0f;	/* field of view in Y */
	nearClip = 3.0f;	/* Near clipping plane location */
	farClip  = 12.0f;	/* Far clipping plane location */
	resetView();
}

GLvoid
keyboard( GLubyte key, GLint x, GLint y ) 
{
	switch (key) {
	case KEY_ESC:
		exit(0);
	}
}

void
resetView( GLvoid )
{
	distance = nearClip + (farClip - nearClip) / 2.0f;
	twistAngle = 0.0f;	/* rotation of viewing volume (camera) */
	incAngle = 0.0f;
	azimAngle = 0.0f;
}

GLvoid
reshape( GLsizei width, GLsizei height )
{
	GLdouble	aspect;

	glViewport( 0, 0, width, height );

	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	aspect = (GLdouble) width / (GLdouble) height;
	gluPerspective( fovy, aspect, nearClip, farClip );
	glMatrixMode( GL_MODELVIEW );
}

void
polarView( GLfloat distance, GLfloat azimuth, GLfloat incidence,
			GLfloat twist)
{
	glTranslatef( 0.0f, 0.0f, -distance);
	glRotatef( -twist, 0.0f, 0.0f, 1.0f);
	glRotatef( -incidence, 1.0f, 0.0f, 0.0f);
	glRotatef( -azimuth, 0.0f, 0.0f, 1.0f);
}

GLvoid
drawScene( GLvoid )
{
	int i,  slices = 8;
	
	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
	glPushMatrix(); 
	
		polarView( distance, azimAngle, incAngle, 0.0f );

		for ( i = 0; i < slices; i++ )
		{
			/* change ambient and diffuse material properties
			 * using GL_COLOR_MATERIAL mode
			 */
			glColor3f( i/10.0f, i/10.0f, 1.0f - i/10.0f ); 
			glPushMatrix(); 
				glRotatef( i * 360.0f/slices, 0.0f, 0.0f, 1.0f );
				glTranslatef( 1.5f, 0.0f, 0.0f );
				glRotatef( i * 360.0f/slices, 0.0f, 1.0f, 0.0f );
				glutSolidTorus( 0.25, 0.75, 8, 15 );
			glPopMatrix();
		}
	glPopMatrix();
	glutSwapBuffers();
}