334 lines
11 KiB
C
334 lines
11 KiB
C
/* ADMesh -- process triangulated solid meshes
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* Copyright (C) 1995, 1996 Anthony D. Martin <amartin@engr.csulb.edu>
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* Copyright (C) 2013, 2014 several contributors, see AUTHORS
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Questions, comments, suggestions, etc to
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* https://github.com/admesh/admesh/issues
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "stl.h"
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static void stl_reverse_facet(stl_file *stl, int facet_num);
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static void stl_reverse_vector(float v[]);
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int stl_check_normal_vector(stl_file *stl, int facet_num, int normal_fix_flag);
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static void
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stl_reverse_facet(stl_file *stl, int facet_num) {
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stl_vertex tmp_vertex;
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/* int tmp_neighbor;*/
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int neighbor[3];
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int vnot[3];
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stl->stats.facets_reversed += 1;
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neighbor[0] = stl->neighbors_start[facet_num].neighbor[0];
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neighbor[1] = stl->neighbors_start[facet_num].neighbor[1];
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neighbor[2] = stl->neighbors_start[facet_num].neighbor[2];
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vnot[0] = stl->neighbors_start[facet_num].which_vertex_not[0];
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vnot[1] = stl->neighbors_start[facet_num].which_vertex_not[1];
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vnot[2] = stl->neighbors_start[facet_num].which_vertex_not[2];
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/* reverse the facet */
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tmp_vertex = stl->facet_start[facet_num].vertex[0];
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stl->facet_start[facet_num].vertex[0] =
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stl->facet_start[facet_num].vertex[1];
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stl->facet_start[facet_num].vertex[1] = tmp_vertex;
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/* fix the vnots of the neighboring facets */
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if(neighbor[0] != -1)
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stl->neighbors_start[neighbor[0]].which_vertex_not[(vnot[0] + 1) % 3] =
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(stl->neighbors_start[neighbor[0]].
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which_vertex_not[(vnot[0] + 1) % 3] + 3) % 6;
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if(neighbor[1] != -1)
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stl->neighbors_start[neighbor[1]].which_vertex_not[(vnot[1] + 1) % 3] =
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(stl->neighbors_start[neighbor[1]].
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which_vertex_not[(vnot[1] + 1) % 3] + 4) % 6;
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if(neighbor[2] != -1)
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stl->neighbors_start[neighbor[2]].which_vertex_not[(vnot[2] + 1) % 3] =
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(stl->neighbors_start[neighbor[2]].
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which_vertex_not[(vnot[2] + 1) % 3] + 2) % 6;
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/* swap the neighbors of the facet that is being reversed */
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stl->neighbors_start[facet_num].neighbor[1] = neighbor[2];
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stl->neighbors_start[facet_num].neighbor[2] = neighbor[1];
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/* swap the vnots of the facet that is being reversed */
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stl->neighbors_start[facet_num].which_vertex_not[1] = vnot[2];
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stl->neighbors_start[facet_num].which_vertex_not[2] = vnot[1];
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/* reverse the values of the vnots of the facet that is being reversed */
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stl->neighbors_start[facet_num].which_vertex_not[0] =
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(stl->neighbors_start[facet_num].which_vertex_not[0] + 3) % 6;
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stl->neighbors_start[facet_num].which_vertex_not[1] =
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(stl->neighbors_start[facet_num].which_vertex_not[1] + 3) % 6;
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stl->neighbors_start[facet_num].which_vertex_not[2] =
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(stl->neighbors_start[facet_num].which_vertex_not[2] + 3) % 6;
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}
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void
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stl_fix_normal_directions(stl_file *stl) {
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char *norm_sw;
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/* int edge_num;*/
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/* int vnot;*/
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int checked = 0;
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int facet_num;
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/* int next_facet;*/
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int i;
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int j;
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struct stl_normal {
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int facet_num;
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struct stl_normal *next;
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};
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struct stl_normal *head;
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struct stl_normal *tail;
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struct stl_normal *newn;
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struct stl_normal *temp;
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if (stl->error) return;
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/* Initialize linked list. */
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head = (struct stl_normal*)malloc(sizeof(struct stl_normal));
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if(head == NULL) perror("stl_fix_normal_directions");
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tail = (struct stl_normal*)malloc(sizeof(struct stl_normal));
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if(tail == NULL) perror("stl_fix_normal_directions");
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head->next = tail;
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tail->next = tail;
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/* Initialize list that keeps track of already fixed facets. */
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norm_sw = (char*)calloc(stl->stats.number_of_facets, sizeof(char));
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if(norm_sw == NULL) perror("stl_fix_normal_directions");
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facet_num = 0;
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/* If normal vector is not within tolerance and backwards:
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Arbitrarily starts at face 0. If this one is wrong, we're screwed. Thankfully, the chances
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of it being wrong randomly are low if most of the triangles are right: */
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if(stl_check_normal_vector(stl, 0, 0) == 2)
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stl_reverse_facet(stl, 0);
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/* Say that we've fixed this facet: */
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norm_sw[facet_num] = 1;
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checked++;
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for(;;) {
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/* Add neighbors_to_list.
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Add unconnected neighbors to the list:a */
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for(j = 0; j < 3; j++) {
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/* Reverse the neighboring facets if necessary. */
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if(stl->neighbors_start[facet_num].which_vertex_not[j] > 2) {
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/* If the facet has a neighbor that is -1, it means that edge isn't shared by another facet */
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if(stl->neighbors_start[facet_num].neighbor[j] != -1) {
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stl_reverse_facet
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(stl, stl->neighbors_start[facet_num].neighbor[j]);
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}
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}
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/* If this edge of the facet is connected: */
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if(stl->neighbors_start[facet_num].neighbor[j] != -1) {
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/* If we haven't fixed this facet yet, add it to the list: */
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if(norm_sw[stl->neighbors_start[facet_num].neighbor[j]] != 1) {
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/* Add node to beginning of list. */
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newn = (struct stl_normal*)malloc(sizeof(struct stl_normal));
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if(newn == NULL) perror("stl_fix_normal_directions");
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newn->facet_num = stl->neighbors_start[facet_num].neighbor[j];
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newn->next = head->next;
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head->next = newn;
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}
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}
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}
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/* Get next facet to fix from top of list. */
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if(head->next != tail) {
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facet_num = head->next->facet_num;
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if(norm_sw[facet_num] != 1) { /* If facet is in list mutiple times */
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norm_sw[facet_num] = 1; /* Record this one as being fixed. */
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checked++;
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}
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temp = head->next; /* Delete this facet from the list. */
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head->next = head->next->next;
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free(temp);
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} else { /* if we ran out of facets to fix: */
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/* All of the facets in this part have been fixed. */
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stl->stats.number_of_parts += 1;
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if(checked >= stl->stats.number_of_facets) {
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/* All of the facets have been checked. Bail out. */
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break;
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} else {
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/* There is another part here. Find it and continue. */
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for(i = 0; i < stl->stats.number_of_facets; i++) {
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if(norm_sw[i] == 0) {
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/* This is the first facet of the next part. */
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facet_num = i;
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if(stl_check_normal_vector(stl, i, 0) == 2) {
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stl_reverse_facet(stl, i);
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}
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norm_sw[facet_num] = 1;
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checked++;
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break;
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}
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}
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}
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}
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}
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free(head);
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free(tail);
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free(norm_sw);
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}
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int
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stl_check_normal_vector(stl_file *stl, int facet_num, int normal_fix_flag) {
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/* Returns 0 if the normal is within tolerance */
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/* Returns 1 if the normal is not within tolerance, but direction is OK */
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/* Returns 2 if the normal is not within tolerance and backwards */
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/* Returns 4 if the status is unknown. */
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float normal[3];
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float test_norm[3];
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stl_facet *facet;
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facet = &stl->facet_start[facet_num];
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stl_calculate_normal(normal, facet);
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stl_normalize_vector(normal);
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if( (ABS(normal[0] - facet->normal.x) < 0.001)
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&& (ABS(normal[1] - facet->normal.y) < 0.001)
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&& (ABS(normal[2] - facet->normal.z) < 0.001)) {
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/* It is not really necessary to change the values here */
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/* but just for consistency, I will. */
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facet->normal.x = normal[0];
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facet->normal.y = normal[1];
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facet->normal.z = normal[2];
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return 0;
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}
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test_norm[0] = facet->normal.x;
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test_norm[1] = facet->normal.y;
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test_norm[2] = facet->normal.z;
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stl_normalize_vector(test_norm);
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if( (ABS(normal[0] - test_norm[0]) < 0.001)
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&& (ABS(normal[1] - test_norm[1]) < 0.001)
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&& (ABS(normal[2] - test_norm[2]) < 0.001)) {
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if(normal_fix_flag) {
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facet->normal.x = normal[0];
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facet->normal.y = normal[1];
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facet->normal.z = normal[2];
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stl->stats.normals_fixed += 1;
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}
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return 1;
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}
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stl_reverse_vector(test_norm);
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if( (ABS(normal[0] - test_norm[0]) < 0.001)
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&& (ABS(normal[1] - test_norm[1]) < 0.001)
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&& (ABS(normal[2] - test_norm[2]) < 0.001)) {
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/* Facet is backwards. */
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if(normal_fix_flag) {
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facet->normal.x = normal[0];
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facet->normal.y = normal[1];
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facet->normal.z = normal[2];
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stl->stats.normals_fixed += 1;
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}
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return 2;
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}
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if(normal_fix_flag) {
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facet->normal.x = normal[0];
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facet->normal.y = normal[1];
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facet->normal.z = normal[2];
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stl->stats.normals_fixed += 1;
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}
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return 4;
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}
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static void
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stl_reverse_vector(float v[]) {
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v[0] *= -1;
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v[1] *= -1;
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v[2] *= -1;
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}
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void
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stl_calculate_normal(float normal[], stl_facet *facet) {
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float v1[3];
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float v2[3];
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v1[0] = facet->vertex[1].x - facet->vertex[0].x;
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v1[1] = facet->vertex[1].y - facet->vertex[0].y;
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v1[2] = facet->vertex[1].z - facet->vertex[0].z;
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v2[0] = facet->vertex[2].x - facet->vertex[0].x;
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v2[1] = facet->vertex[2].y - facet->vertex[0].y;
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v2[2] = facet->vertex[2].z - facet->vertex[0].z;
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normal[0] = (float)((double)v1[1] * (double)v2[2]) - ((double)v1[2] * (double)v2[1]);
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normal[1] = (float)((double)v1[2] * (double)v2[0]) - ((double)v1[0] * (double)v2[2]);
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normal[2] = (float)((double)v1[0] * (double)v2[1]) - ((double)v1[1] * (double)v2[0]);
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}
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void stl_normalize_vector(float v[]) {
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double length;
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double factor;
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float min_normal_length;
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length = sqrt((double)v[0] * (double)v[0] + (double)v[1] * (double)v[1] + (double)v[2] * (double)v[2]);
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min_normal_length = 0.000000000001;
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if(length < min_normal_length) {
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v[0] = 0.0;
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v[1] = 0.0;
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v[2] = 0.0;
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return;
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}
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factor = 1.0 / length;
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v[0] *= factor;
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v[1] *= factor;
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v[2] *= factor;
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}
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void
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stl_fix_normal_values(stl_file *stl) {
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int i;
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if (stl->error) return;
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for(i = 0; i < stl->stats.number_of_facets; i++) {
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stl_check_normal_vector(stl, i, 1);
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}
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}
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void
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stl_reverse_all_facets(stl_file *stl) {
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int i;
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float normal[3];
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if (stl->error) return;
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for(i = 0; i < stl->stats.number_of_facets; i++) {
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stl_reverse_facet(stl, i);
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stl_calculate_normal(normal, &stl->facet_start[i]);
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stl_normalize_vector(normal);
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stl->facet_start[i].normal.x = normal[0];
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stl->facet_start[i].normal.y = normal[1];
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stl->facet_start[i].normal.z = normal[2];
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}
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}
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