#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <sys/types.h>
#include <sys/time.h>
#include <GL/glut.h>

extern double drand48(void);
extern void srand48(long seedval);


#define XSIZE 100
#define YSIZE 75

#define RINGS 5
#define BLUERING 0
#define BLACKRING 1
#define REDRING 2
#define YELLOWRING 3
#define GREENRING 4

#define BACKGROUND 8

enum {
    BLACK = 0,
    RED,
    GREEN,
    YELLOW,
    BLUE,
    MAGENTA,
    CYAN,
    WHITE
};


GLenum rgb, doubleBuffer;

unsigned char rgb_colors[RINGS][3];
int mapped_colors[RINGS];
float dests[RINGS][3];
float offsets[RINGS][3];
float angs[RINGS];
float rotAxis[RINGS][3];
int iters[RINGS];
GLuint theTorus;


void FillTorus(float rc, int numc, float rt, int numt)
{
    int i, j, k;
    double s, t;
    double x, y, z;
    double pi, twopi;

    pi = 3.14159265358979323846;
    twopi = 2 * pi;
 
    for (i = 0; i < numc; i++) {
	glBegin(GL_QUAD_STRIP);
	    for (j = 0; j <= numt; j++) {
		for (k = 1; k >= 0; k--) {
		    s = (i + k) % numc + 0.5;
		    t = j % numt;

		    x = cos(t*twopi/numt) * cos(s*twopi/numc);
		    y = sin(t*twopi/numt) * cos(s*twopi/numc);
		    z = sin(s*twopi/numc);
		    glNormal3f(x, y, z);

		    x = (rt + rc * cos(s*twopi/numc)) * cos(t*twopi/numt);
		    y = (rt + rc * cos(s*twopi/numc)) * sin(t*twopi/numt);
		    z = rc * sin(s*twopi/numc);
		    glVertex3f(x, y, z);
		}
	    }
	glEnd();
    }
}

float Clamp(int iters_left, float t)
{

    if (iters_left < 3) {
	return 0.0;
    }
    return (iters_left-2)*t/iters_left;
}

void DrawScene(void)
{
    int i, j;
    GLboolean goIdle;

    goIdle = GL_TRUE;
    for (i = 0; i < RINGS; i++) {
	if (iters[i]) {
	    for (j = 0; j < 3; j++) {
		offsets[i][j] = Clamp(iters[i], offsets[i][j]);
	    }
	    angs[i] = Clamp(iters[i], angs[i]);
	    iters[i]--;
	    goIdle = GL_FALSE;
	}
    }
    if (goIdle) {
       glutIdleFunc(NULL);
    }

    glPushMatrix();
    
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    gluLookAt(0,0,10, 0,0,0, 0,1,0);

    for (i = 0; i < RINGS; i++) {
	if (rgb) {
	    glColor3ubv(rgb_colors[i]);
	} else {
	    glIndexi(mapped_colors[i]);
	}
	glPushMatrix();
	glTranslatef(dests[i][0]+offsets[i][0], dests[i][1]+offsets[i][1],
		     dests[i][2]+offsets[i][2]);
	glRotatef(angs[i], rotAxis[i][0], rotAxis[i][1], rotAxis[i][2]);
	glCallList(theTorus);
	glPopMatrix();
    }

    glPopMatrix();

    if (doubleBuffer) {
	glutSwapBuffers();
    } else {
	glFlush();
    }
}

float MyRand(void)
{

    return 10.0 * (drand48() - 0.5);
}

void ReInit(void)
{
    int i;
    float deviation;

    deviation = MyRand() / 2;
    deviation = deviation * deviation;
    for (i = 0; i < RINGS; i++) {
	offsets[i][0] = MyRand();
	offsets[i][1] = MyRand();
	offsets[i][2] = MyRand();
	angs[i] = 260.0 * MyRand();
	rotAxis[i][0] = MyRand();
	rotAxis[i][1] = MyRand();
	rotAxis[i][2] = MyRand();
	iters[i] = (deviation * MyRand() + 60.0);
    }
    glutIdleFunc(DrawScene);
}

void Init(void)
{
    int i;
    struct timeval t;
    struct timezone tz;
    float top_y = 1.0;
    float bottom_y = 0.0;
    float top_z = 0.15;
    float bottom_z = 0.69;
    float spacing = 2.5;
    static float lmodel_ambient[] = {0.0, 0.0, 0.0, 0.0};
    static float lmodel_twoside[] = {GL_FALSE};
    static float lmodel_local[] = {GL_FALSE};
    static float light0_ambient[] = {0.1, 0.1, 0.1, 1.0};
    static float light0_diffuse[] = {1.0, 1.0, 1.0, 0.0};
    static float light0_position[] = {0.8660254, 0.5, 1, 0};
    static float light0_specular[] = {1.0, 1.0, 1.0, 0.0};
    static float bevel_mat_ambient[] = {0.0, 0.0, 0.0, 1.0};
    static float bevel_mat_shininess[] = {40.0};
    static float bevel_mat_specular[] = {1.0, 1.0, 1.0, 0.0};
    static float bevel_mat_diffuse[] = {1.0, 0.0, 0.0, 0.0};

    gettimeofday(&t, &tz);
    srand48(t.tv_usec);
    ReInit();
    for (i = 0; i < RINGS; i++) {
	rgb_colors[i][0] = rgb_colors[i][1] = rgb_colors[i][2] = 0;
    }
    rgb_colors[BLUERING][2] = 255;
    rgb_colors[REDRING][0] = 255;
    rgb_colors[GREENRING][1] = 255;
    rgb_colors[YELLOWRING][0] = 255;
    rgb_colors[YELLOWRING][1] = 255;
    mapped_colors[BLUERING] = BLUE;
    mapped_colors[REDRING] = RED;
    mapped_colors[GREENRING] = GREEN;
    mapped_colors[YELLOWRING] = YELLOW;
    mapped_colors[BLACKRING] = BLACK;

    dests[BLUERING][0] = -spacing;
    dests[BLUERING][1] = top_y;
    dests[BLUERING][2] = top_z;

    dests[BLACKRING][0] = 0.0;
    dests[BLACKRING][1] = top_y;
    dests[BLACKRING][2] = top_z;

    dests[REDRING][0] = spacing;
    dests[REDRING][1] = top_y;
    dests[REDRING][2] = top_z;

    dests[YELLOWRING][0] = -spacing / 2.0;
    dests[YELLOWRING][1] = bottom_y;
    dests[YELLOWRING][2] = bottom_z;

    dests[GREENRING][0] = spacing / 2.0;
    dests[GREENRING][1] = bottom_y;
    dests[GREENRING][2] = bottom_z;

    theTorus = glGenLists(1);
    glNewList(theTorus, GL_COMPILE);
    FillTorus(0.1, 8, 1.0, 25);
    glEndList();

    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);
    glEnable(GL_DEPTH_TEST);
    glClearDepth(1.0);

    if (rgb) {
	glClearColor(0.5, 0.5, 0.5, 0.0);
	glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambient);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
	glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);
	glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
	glEnable(GL_LIGHT0);

	glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, lmodel_local);
	glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
	glEnable(GL_LIGHTING);

	glMaterialfv(GL_FRONT, GL_AMBIENT, bevel_mat_ambient);
	glMaterialfv(GL_FRONT, GL_SHININESS, bevel_mat_shininess);
	glMaterialfv(GL_FRONT, GL_SPECULAR, bevel_mat_specular);
	glMaterialfv(GL_FRONT, GL_DIFFUSE, bevel_mat_diffuse);

	glColorMaterial(GL_FRONT_AND_BACK, GL_DIFFUSE);
	glEnable(GL_COLOR_MATERIAL);
	glShadeModel(GL_SMOOTH);
    } else {
	glClearIndex(BACKGROUND);
	glShadeModel(GL_FLAT);
    }

    glMatrixMode(GL_PROJECTION);
    gluPerspective(45, 1.33, 0.1, 100.0);
    glMatrixMode(GL_MODELVIEW);
}

void Reshape(int width, int height)
{

    glViewport(0, 0, width, height);
}

void Key(unsigned char key, int x, int y)
{

    switch (key) {
      case ' ' :
	ReInit();
	break;
      case 27:
	exit(0);
    }
}

void Args(int argc, char **argv)
{
    GLint i;

    rgb = GL_TRUE;
    doubleBuffer = GL_FALSE;

    for (i = 1; i < argc; i++) {
	if (strcmp(argv[i], "-ci") == 0) {
	    rgb = GL_FALSE;
	} else if (strcmp(argv[i], "-rgb") == 0) {
	    rgb = GL_TRUE;
	} else if (strcmp(argv[i], "-sb") == 0) {
	    doubleBuffer = GL_FALSE;
	} else if (strcmp(argv[i], "-db") == 0) {
	    doubleBuffer = GL_TRUE;
	}
    }
}

int main(int argc, char **argv)
{
    GLenum type;

    glutInit(&argc, argv);
    Args(argc, argv);

    type = GLUT_DEPTH;
    type |= (rgb) ? GLUT_RGB : GLUT_INDEX;
    type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
    glutInitDisplayMode(type);
    glutInitWindowSize(300, 300);
    glutCreateWindow("Olympic");

    Init();
    ReInit();

    glutReshapeFunc(Reshape);
    glutKeyboardFunc(Key);
    glutDisplayFunc(DrawScene);
    glutMainLoop();
}
