/*
 * solid.c - Data structure and handling of a solid made of two opposing faces
 *
 * Written 2010 by Werner Almesberger
 * Copyright 2010 by Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>

#include "face.h"
#include "solid.h"


static void height_field(const char *name, const struct face *f,
    const struct matrix *m)
{
	FILE *file;
	int x, y;
	int z;
	uint16_t g;
	uint8_t v[2];

	file = fopen(name, "w");
	if (!file) {
		perror(name);
		exit(1);
	}
	fprintf(file, "P5\n%d %d\n65535\n", f->sx, f->sy);
	for (y = 0; y != f->sy; y++)
		for (x = 0; x != f->sx; x++) {
			z = get(f->a, x+f->a->min_x, y+f->a->min_y);
			g = z == UNDEF ? 0 :
			    65535*(z-f->a->min_z)/(f->a->max_z-f->a->min_z);
			v[0] = g >> 8;
			v[1] = g;
			fwrite(v, 2, 1, file);
		}
	fclose(file);
}


static void sanitize(const char *s, char *res)
{
	while (*s) {
		if ((*s >= 'A' && *s <= 'Z') ||
		    (*s >= 'a' && *s <= 'z') ||
		    (*s >= '0' && *s <= '9') || *s == '_')
			*res = *s;
		else
			*res = '_';
		res++;
		s++;
	}
	*res = 0;
}


void povray(const char *name, const struct solid *s)
{
	struct matrix m;
	char tmp[1000]; /* @@@ enough */

	m.a[0][0] = m.a[1][1] = 1;
	m.a[0][1] = m.a[1][0] = 0;
	m.b[0] = m.b[1] = 0;

	sprintf(tmp, "%s-top.pgm", name);
	height_field(tmp, s->a, &m);
	sprintf(tmp, "%s-bot.pgm", name);
	height_field(tmp, s->b, &m);

	/*
	 * 1/65535 = 0.000015..., so we set the water level a bit lower, e.g.,
	 * to 0.0001
	 */
	sanitize(name, tmp);
	printf(
"#declare Part_%s =\n"
"    intersection {\n"
"        height_field { pgm \"%s-top.pgm\" water_level 0.00001 smooth }\n"
"        height_field { pgm \"%s-bot.pgm\" water_level 0.00001 smooth }\n"
"    }\n", tmp, name, name);
}