cae-tools/slicer/stl.c

/*
 * stl.c - STL file reading
 *
 * Written 2014-2015 by Werner Almesberger
 * Copyright 2014-2015 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.
 */

/*
 * Format description:
 * http://en.wikipedia.org/wiki/STL_%28file_format%29
 */


#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <math.h>

#include "stl.h"


#define	MAX_LINE	100


enum state {
	s_init,
	s_facet,
	s_loop,
	s_vertices,
	s_endloop,
	s_endfacet,
};


static void stl_load_binary(FILE *file, void (*facet)(struct v f[3]))
{
	char discard[75];
	size_t n;
	uint32_t nf;
	uint16_t attr;
	float tmp[4*3];
	struct v f[3];
	int i;

	n = fread(discard, 1, sizeof(discard), file);
	if (n != sizeof(discard)) {
		fprintf(stderr, "incomplete header\n");
		exit(1);
	}
	n = fread(&nf, 1, sizeof(nf), file);
	if (n != sizeof(nf)) {
		fprintf(stderr, "no number of facets\n");
		exit(1);
	}
	while (nf--) {
		n = fread(&tmp, 1, sizeof(tmp), file);
		if (n != sizeof(tmp)) {
			fprintf(stderr, "incomplete facet\n");
			exit(1);
		}
		for (i = 0; i != 3; i++) {
			f[i].x = tmp[3 * i + 3];
			f[i].y = tmp[3 * i + 4];
			f[i].z = tmp[3 * i + 5];
		}
		facet(f);
		n = fread(&attr, 1, sizeof(attr), file);
		if (n != sizeof(attr)) {
			fprintf(stderr, "no attribute count\n");
			exit(1);
		}
		if (attr) {
			fprintf(stderr, "non-zero attribute count\n");
			exit(1);
		}
	}
}


static void stl_load_text(FILE *file, void (*facet)(struct v f[3]))
{
	char buf[MAX_LINE + 1];
	enum state state = s_init;
	struct v f[3];
	int num_v = 0;
	char *s, *e;
	int n = 0;
	int end, got;

	while (fgets(buf, sizeof(buf), file)) {
		n++;
		if (!(n & 1023))
			fprintf(stderr, "%d\r", n);

		for (s = buf; *s && isspace(*s); s++);
		e = strchr(s, 0);
		while (e != s && isspace(e[-1]))
				e--;
		*e = 0;
		end = 0;

		switch (state) {
		case s_init:
			sscanf(s, " %*s%n", &end);
			state = s_facet;
			break;
		case s_facet:
			if (!strncmp(s, "endsolid", 8))
				return;
			sscanf(s, "facet normal %*f %*f %*f%n", &end);
			state = s_loop;
			break;
		case s_loop:
			sscanf(s, "outer loop%n", &end);
			state = s_vertices;
			num_v = 0;
			break;
		case s_vertices:
			got = sscanf(s, "vertex %f %f %f%n",
			    &f[num_v].x, &f[num_v].y, &f[num_v].z, &end);
			if (got < 3)
				break;
			if (++num_v == 3) {
				facet(f);
				state = s_endloop;
			}
			break;
		case s_endloop:
			sscanf(s, "endloop%n", &end);
			state = s_endfacet;
			break;
		case s_endfacet:
			sscanf(s, "endfacet%n", &end);
			state = s_facet;
			break;
		}
		if (end != e - s) {
			fprintf(stderr, "cannot parse line %d (%d %ld)\n",
			     n, end, e - s);
			exit(1);
		}
	}
	fprintf(stderr, "incomplete STL file\n");
	exit(1);

}


void stl_load_file(FILE *file, void (*facet)(struct v f[3]))
{
	char buf[5];
	size_t n;

	n = fread(buf, 1, sizeof(buf), file);
	if (n != sizeof(buf)) {
		fprintf(stderr, "file too short\n");
		exit(1);
	}

	if (memcmp(buf, "solid", 5)) {
		stl_load_binary(file, facet);
	} else {
		stl_load_text(file, facet);
	}
}


void stl_load(const char *name, void (*facet)(struct v f[3]))
{
	FILE *file;

	file = fopen(name, "r");
	if (!file) {
		perror(name);
		exit(1);
	}
	stl_load_file(file, facet);
	fclose(file);
}