/* demoSweepVol.c  */

/* Purpose: Construct a shape and sweep it around the y-axis */


#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define KEY_ESC 27  /* GLUT doesn't supply this  */

#define MAXOUTLINES 30 /* maximum number of discrete steps  */
#define MAXPOINTS 30   /* maximum number of points in outline */


/* Global Definitions */
struct mPoint3D
{
	GLfloat x;
	GLfloat y;
	GLfloat z;
};


/* This contains the vertex data for the lamp outline */
struct mPoint3D mV[MAXPOINTS] = {
	{0.0, 0.0, 0.0},
	{0.1, 0.0, 0.0},
	{0.2, 0.0, 0.0},
	{0.3, 0.0, 0.0},
	{0.4, 0.0, 0.0},
	{0.5, 0.0, 0.0},
	{0.5, 0.3, 0.0},
	{0.5, 0.4, 0.0},
	{0.4, 0.55, 0.0},
	{0.3, 0.7, 0.0},
	{0.2, 0.8, 0.0},
	{0.2, 1.0, 0.0},
	{0.3, 1.0, 0.0},
	{0.4, 1.0, 0.0},
	{0.5, 1.0, 0.0},
	{0.6, 1.0, 0.0},
	{0.7, 1.0, 0.0},
	{0.8, 1.0, 0.0},
	{0.9, 1.0, 0.0},
	{1.0, 1.0, 0.0},
	{0.9, 1.05, 0.0},
	{0.8, 1.1, 0.0},
	{0.7, 1.15, 0.0},
	{0.6, 1.2, 0.0},
	{0.5, 1.25, 0.0},
	{0.4, 1.3, 0.0},
	{0.3, 1.35, 0.0},
	{0.2, 1.4, 0.0},
	{0.1, 1.45, 0.0},
	{0.0, 1.5, 0.0}
};

void printHelp( void )
{
	fprintf(stdout,
		"\ndemoSweepVol - 3D shape from 2D outline\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 checkError( const char* const label )
{
	GLenum error;
	error = glGetError();
	while (GL_NO_ERROR != error )
	{
		fprintf(stderr,"%s: %s\n", label, gluErrorString(error) );
		error = glGetError();
	}
}


/* draw outline of lamp */
GLvoid drawOutline( GLvoid )
{
	int loop;

	glBegin(GL_LINE_STRIP);
	for( loop = 0; loop < MAXPOINTS; ++loop)
	{
		glVertex3f( mV[loop].x, mV[loop].y, mV[loop].z );
	}
	glEnd();
}


/* Sweep the outline around the y axis */
GLvoid sweepOutline( GLvoid )
{
	GLint loop;

	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	for( loop = 0; loop < MAXOUTLINES ; ++loop )
	{
		float frac = (float)loop / MAXOUTLINES; /* frac will run from 0 to a bit less than 1 */
		glLoadIdentity();
		glRotatef( frac * 360, 0.0, 1.0, 0.0 );
		glColor3f(1.0 - frac, 0.0, frac); /* change colour to show up separate outlines */
		drawOutline();
	}

	checkError( "sweepOutline" );

	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 );

	glLineWidth(3.0);

	glEnable(GL_DEPTH_TEST);
}

int main( int argc, char *argv[] )
{
	glutInit( &argc, argv );
	glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH );
	glutCreateWindow( argv[0] );

	init();

    glutKeyboardFunc( keyboard );
	glutDisplayFunc( sweepOutline );

	printHelp( );

	glutMainLoop();

	return 0;
}