/*
 * 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.
 */


/*  flicker_arm.c - animates a robot arm in single buffer mode to 
 *			 demonstrate the flicker problem
 *
 *  <r> Key			- toggle arm rotation on / off
 *  Escape key 		 	- exit the program 
 */

#include <GL/glut.h>	/* includes gl.h, glu.h */
#include <math.h>	/* for fmod */
#include <stdlib.h>	/* for NULL */
#include <stdio.h>	/* for printf */

#include "axes.h"
#include "shapes.h"

/*  Function Prototypes  */

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

void printHelp( char * );

/*  Global Variables */

static GLfloat	shoulderAngle = 0.0f;	/* controls shoulder rotation */

static GLboolean	rotateFlag = GL_TRUE;

/* Global Definitions */

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

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

	glutInit( &argc, argv );

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

	initgfx();

	glutIdleFunc( animate );
	glutVisibilityFunc( visibility );
	glutKeyboardFunc( keyboard );
	glutReshapeFunc( reshape );
	glutDisplayFunc( drawScene ); 

	printHelp( argv[0] );

	glutMainLoop();
}

void
printHelp( char *progname )
{
	fprintf(stdout, "\n%s - animate a robot arm\n\n"
		"Axes: X - red, Y - green, Z - blue\n\n"
		"<r> Key		- toggle arm rotation on / off\n"
		"Escape Key		- exit the program\n",
		progname);
}

GLvoid
initgfx( GLvoid )
{
	glClearColor( 0.0, 0.0, 0.0, 1.0 );
	glShadeModel( GL_FLAT );
	glEnable( GL_DEPTH_TEST );
}

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

	glViewport( 0, 0, width, height );

	aspect = (GLdouble) width / (GLdouble) height;

	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	gluPerspective( 45.0, aspect, 1.0, 20.0 );
	glMatrixMode( GL_MODELVIEW );
}

GLvoid 
keyboard( GLubyte key, GLint x, GLint y )
{
	switch (key) {
	case 'r':
		rotateFlag = !rotateFlag;
		if (rotateFlag) {
			glutIdleFunc( animate );
		} else {
			glutIdleFunc( NULL );
		}
		break;
	case KEY_ESC:	/* Exit when the Escape key is pressed */
		exit(0);
	}
}

GLvoid 
animate( GLvoid )
{
	/* update the rotation of the shoulder for each scene */
	shoulderAngle = fmod( (shoulderAngle + 1.0), 360.0 );

	glutPostRedisplay();	/* Tell GLUT to redraw the scene */
}

GLvoid
visibility( int state ) 
{
	/* restart the animation function if we were
	 * animated when the window was hidden
	 */
	if (state == GLUT_VISIBLE && rotateFlag) {
		glutIdleFunc( animate );
	} else {
		glutIdleFunc( NULL );
	}
}

GLvoid
drawScene( GLvoid )
{
    static GLfloat    upperArmColor[] = { 0.5f, 0.5f, 0.8f };
    static GLfloat    lowerArmColor[] = { 0.5f, 0.8f, 0.5f };

	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

	glPushMatrix();
		gluLookAt( 0.0, 0.0, 8.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0 );
		XYaxes();

        glPushAttrib( GL_LINE_BIT );
        glLineWidth( 2.0 );

		/* rotate the shoulder by shoulderAngle degrees */
		glRotatef( shoulderAngle, 0.0f, 0.0f, 1.0f );

		/* Draw the upper arm */
		glTranslatef( 1.0f, 0.0f, 0.0f ); 
    		glColor3fv( upperArmColor );
		WireBox( 2.0, 0.4, 1.0 );

		/* Draw the lower arm */
		glTranslatef( 1.0f, 0.0f, 0.0f );
		glRotatef( 45.0f, 0.0f, 0.0f, 1.0f );
		glTranslatef( 1.0f, 0.0f, 0.0f );
    		glColor3fv( lowerArmColor );
		WireBox( 2.0, 0.4, 1.0 );

        glPopAttrib();

	glPopMatrix();
	glFlush();
}