// Peter Bui
// CSE 40166 Computer Graphics (Fall 2010)
// Lab 2: fun with OpenGL polygons

#include "color.h"
 
#include <cmath>
#include <cstdio>
#include <cstdlib>

#include <vector>
#include <unistd.h>

#include <GL/glut.h>

using namespace std;

// Type definition -------------------------------------------------------------

typedef struct {
    GLfloat x;
    GLfloat y;
} point;

// Constants -------------------------------------------------------------------

#define NPRIMITIVES 6
int PRIMITIVES[NPRIMITIVES] = {
    GL_POLYGON,
    GL_TRIANGLES,
    GL_TRIANGLE_STRIP,
    GL_TRIANGLE_FAN,
    GL_QUADS,
    GL_QUAD_STRIP
};

// Global variables ------------------------------------------------------------

static int WindowWidth  = 640;
static int WindowHeight = 480;

static int BackgroundColor = COLOR_BLACK;

static vector<point> Points;

// Initialize viewing ----------------------------------------------------------

void
init()
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-5.0, 10.0, -5.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
    
    glClearColor(ColorTable[BackgroundColor][0],
		 ColorTable[BackgroundColor][1], 
		 ColorTable[BackgroundColor][2], 
		 1.0);

    glEnable(GL_POINT_SMOOTH);
}

// Read in points --------------------------------------------------------------

void
read_points(const char *fname)
{
    FILE *fs;
    point p;

    fs = fopen(fname, "r");
    if (!fs) {
	fprintf(stderr, "polygons: could not open file %s\n", fname);
	exit(EXIT_FAILURE);
    }

    while (fscanf(fs, "%f %f", &p.x, &p.y) == 2)
	Points.push_back(p);

    fclose(fs);
}

// Display callback ------------------------------------------------------------

void 
display()
{
    int ViewportWidth  = WindowWidth*2  / NPRIMITIVES;
    int ViewportHeight = WindowHeight*3 / NPRIMITIVES;

    glClear(GL_COLOR_BUFFER_BIT);

    for (int p = 0; p < NPRIMITIVES; p++) {
	glViewport((p % 3) * ViewportWidth, (p < 3) ? ViewportHeight : 0, ViewportWidth, ViewportHeight);

	glBegin(PRIMITIVES[p]); {
	    for (size_t i = 0; i < Points.size(); i++) {
		glColor3fv(color_rotate());
		glVertex2f(Points[i].x, Points[i].y);
	    }
	} glEnd();
    }
    
    glFlush();
}

// Show usage ------------------------------------------------------------------

void
show_usage()
{
    printf("usage: polygons [options] <datafile>\n");
    printf("General Options:\n");
    printf("  -h             Show this help message\n");
    printf("\nWindow Options:\n");
    printf("  -W <width>     Set window width\n");
    printf("  -H <height>    Set window height\n");
}

// Parse command line arguments ------------------------------------------------
    
void
parse_command_line_arguments(int argc, char *argv[])
{
    int c;

    while ((c = getopt(argc, argv, "W:H:h")) >= 0) {
	switch (c) {
	    case 'W': 
		WindowWidth  = strtol(optarg, NULL, 10); 
		break;
	    case 'H': 
		WindowHeight = strtol(optarg, NULL, 10); 
		break;
	    case 'h':
		show_usage();
		exit(EXIT_SUCCESS);
		break;
	    default:
		fprintf(stderr, "polygons: unknown command line argument %c\n", c);
		show_usage();
		exit(EXIT_FAILURE);
		break;
	}
    }

    if ((argc - optind) != 1) {
	show_usage();
	exit(EXIT_FAILURE);
    } else {
	read_points(argv[optind]);
    }
}

// Main execution --------------------------------------------------------------

int 
main(int argc, char *argv[])
{
    glutInit(&argc, argv);

    parse_command_line_arguments(argc, argv);

    glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
    glutInitWindowSize(WindowWidth, WindowHeight);
    glutCreateWindow("polygons");
    glutDisplayFunc(display);
    init();
    glutMainLoop();	

    return (EXIT_SUCCESS);
}

// vim: sts=4 sw=4 ts=8 ft=cpp