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util.c

/*  ADMesh -- process triangulated solid meshes
 *  Copyright (C) 1995, 1996  Anthony D. Martin
 *
 *  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, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *  
 *  Questions, comments, suggestions, etc to <amartin@engr.csulb.edu>
 */

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

#include "stl.h"

static void stl_rotate(float *x, float *y, float angle);
static void stl_get_size(stl_file *stl);
static float get_area(stl_facet *facet);
static float get_volume(stl_file *stl);


void
stl_verify_neighbors(stl_file *stl)
{
  int i;
  int j;
  stl_edge edge_a;
  stl_edge edge_b;
  int neighbor;
  int vnot;

  stl->stats.backwards_edges = 0;

  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        edge_a.p1 = stl->facet_start[i].vertex[j];
        edge_a.p2 = stl->facet_start[i].vertex[(j + 1) % 3];
        neighbor = stl->neighbors_start[i].neighbor[j];
        vnot = stl->neighbors_start[i].which_vertex_not[j];
        
        if(neighbor == -1)
          continue;           /* this edge has no neighbor... Continue. */
        if(vnot < 3)
          {
            edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
            edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
          }
        else
          {
            stl->stats.backwards_edges += 1;
            edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
            edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
          }
        if(memcmp(&edge_a, &edge_b, SIZEOF_EDGE_SORT) != 0)
          {
            /* These edges should match but they don't.  Print results. */
            printf("edge %d of facet %d doesn't match edge %d of facet %d\n",
                 j, i, vnot + 1, neighbor);
            stl_write_facet(stl, "first facet", i);
            stl_write_facet(stl, "second facet", neighbor);
          }
      }
    }
}

void
stl_translate(stl_file *stl, float x, float y, float z)
{
  int i;
  int j;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->facet_start[i].vertex[j].x -= (stl->stats.min.x - x);
        stl->facet_start[i].vertex[j].y -= (stl->stats.min.y - y);
        stl->facet_start[i].vertex[j].z -= (stl->stats.min.z - z);
      }
    }
  stl->stats.max.x -= (stl->stats.min.x - x);
  stl->stats.max.y -= (stl->stats.min.y - y);
  stl->stats.max.z -= (stl->stats.min.z - z);
  stl->stats.min.x = x;
  stl->stats.min.y = y;
  stl->stats.min.z = z;
}

void
stl_scale(stl_file *stl, float factor)
{
  int i;
  int j;
  
  stl->stats.min.x *= factor;
  stl->stats.min.y *= factor;
  stl->stats.min.z *= factor;
  stl->stats.max.x *= factor;
  stl->stats.max.y *= factor;
  stl->stats.max.z *= factor;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->facet_start[i].vertex[j].x *= factor;
        stl->facet_start[i].vertex[j].y *= factor;
        stl->facet_start[i].vertex[j].z *= factor;
      }
    }
}

static void calculate_normals(stl_file *stl)
{
      long i;
      float normal[3];
      
      for(i = 0; i < stl->stats.number_of_facets; i++){
            stl_calculate_normal(normal, &stl->facet_start[i]);
            stl_normalize_vector(normal);
            stl->facet_start[i].normal.x = normal[0];
            stl->facet_start[i].normal.y = normal[1];
            stl->facet_start[i].normal.z = normal[2];
      }
}

void
stl_rotate_x(stl_file *stl, float angle)
{
  int i;
  int j;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl_rotate(&stl->facet_start[i].vertex[j].y,
                 &stl->facet_start[i].vertex[j].z, angle);
      }
    }
  stl_get_size(stl);
      calculate_normals(stl);
}

void
stl_rotate_y(stl_file *stl, float angle)
{
  int i;
  int j;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl_rotate(&stl->facet_start[i].vertex[j].z,
                 &stl->facet_start[i].vertex[j].x, angle);
      }
    }
  stl_get_size(stl);
      calculate_normals(stl);
}

void
stl_rotate_z(stl_file *stl, float angle)
{
  int i;
  int j;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl_rotate(&stl->facet_start[i].vertex[j].x,
                 &stl->facet_start[i].vertex[j].y, angle);
      }
    }
  stl_get_size(stl);
      calculate_normals(stl);
}

            

static void
stl_rotate(float *x, float *y, float angle)
{
  double r;
  double theta;
  double radian_angle;
  
  radian_angle = (angle / 180.0) * M_PI;
  
  r = sqrt((*x * *x) + (*y * *y));
  theta = atan2(*y, *x);
  *x = r * cos(theta + radian_angle);
  *y = r * sin(theta + radian_angle);
}

static void
stl_get_size(stl_file *stl)
{
  int i;
  int j;

  stl->stats.min.x = stl->facet_start[0].vertex[0].x;
  stl->stats.min.y = stl->facet_start[0].vertex[0].y;
  stl->stats.min.z = stl->facet_start[0].vertex[0].z;
  stl->stats.max.x = stl->facet_start[0].vertex[0].x;
  stl->stats.max.y = stl->facet_start[0].vertex[0].y;
  stl->stats.max.z = stl->facet_start[0].vertex[0].z;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->stats.min.x = STL_MIN(stl->stats.min.x,
                             stl->facet_start[i].vertex[j].x);
        stl->stats.min.y = STL_MIN(stl->stats.min.y,
                             stl->facet_start[i].vertex[j].y);
        stl->stats.min.z = STL_MIN(stl->stats.min.z,
                             stl->facet_start[i].vertex[j].z);
        stl->stats.max.x = STL_MAX(stl->stats.max.x,
                             stl->facet_start[i].vertex[j].x);
        stl->stats.max.y = STL_MAX(stl->stats.max.y,
                             stl->facet_start[i].vertex[j].y);
        stl->stats.max.z = STL_MAX(stl->stats.max.z,
                             stl->facet_start[i].vertex[j].z);
      }
    }
}

void
stl_mirror_xy(stl_file *stl)
{
  int i;
  int j;
  float temp_size;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->facet_start[i].vertex[j].z *= -1.0;
      }
    }
  temp_size = stl->stats.min.z;
  stl->stats.min.z = stl->stats.max.z;
  stl->stats.max.z = temp_size;
  stl->stats.min.z *= -1.0;
  stl->stats.max.z *= -1.0;
}

void
stl_mirror_yz(stl_file *stl)
{
  int i;
  int j;
  float temp_size;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->facet_start[i].vertex[j].x *= -1.0;
      }
    }
  temp_size = stl->stats.min.x;
  stl->stats.min.x = stl->stats.max.x;
  stl->stats.max.x = temp_size;
  stl->stats.min.x *= -1.0;
  stl->stats.max.x *= -1.0;
}

void
stl_mirror_xz(stl_file *stl)
{
  int i;
  int j;
  float temp_size;
  
  for(i = 0; i < stl->stats.number_of_facets; i++)
    {
      for(j = 0; j < 3; j++)
      {
        stl->facet_start[i].vertex[j].y *= -1.0;
      }
    }
  temp_size = stl->stats.min.y;
  stl->stats.min.y = stl->stats.max.y;
  stl->stats.max.y = temp_size;
  stl->stats.min.y *= -1.0;
  stl->stats.max.y *= -1.0;
}

static float get_volume(stl_file *stl)
{
      long i;
      stl_vertex p0;
      stl_vertex p;
      stl_normal n;
      float height;
      float area;
      float volume = 0.0;
      
      /* Choose a point, any point as the reference */
      p0.x = stl->facet_start[0].vertex[0].x;
      p0.y = stl->facet_start[0].vertex[0].y;
      p0.z = stl->facet_start[0].vertex[0].z;

      for(i = 0; i < stl->stats.number_of_facets; i++){
            p.x = stl->facet_start[i].vertex[0].x - p0.x;
            p.y = stl->facet_start[i].vertex[0].y - p0.y;
            p.z = stl->facet_start[i].vertex[0].z - p0.z;
            /* Do dot product to get distance from point to plane */
            n = stl->facet_start[i].normal;
            height = (n.x * p.x) + (n.y * p.y) + (n.z * p.z);
            area = get_area(&stl->facet_start[i]);
            volume += (area * height) / 3.0;
      }
      return volume;
}

void stl_calculate_volume(stl_file *stl)
{
      stl->stats.volume = get_volume(stl);
      if(stl->stats.volume < 0.0){
            stl_reverse_all_facets(stl);
            stl->stats.volume = -stl->stats.volume;
      }
}

static float get_area(stl_facet *facet)
{
      float cross[3][3];
      float sum[3];
      float n[3];
      float area;
      int i;
      
      for(i = 0; i < 3; i++){
          cross[i][0]=((facet->vertex[i].y * facet->vertex[(i + 1) % 3].z) -
                   (facet->vertex[i].z * facet->vertex[(i + 1) % 3].y));
          cross[i][1]=((facet->vertex[i].z * facet->vertex[(i + 1) % 3].x) -
                   (facet->vertex[i].x * facet->vertex[(i + 1) % 3].z));
          cross[i][2]=((facet->vertex[i].x * facet->vertex[(i + 1) % 3].y) -
                   (facet->vertex[i].y * facet->vertex[(i + 1) % 3].x));
      }
      
      sum[0] = cross[0][0] + cross[1][0] + cross[2][0];
      sum[1] = cross[0][1] + cross[1][1] + cross[2][1];
      sum[2] = cross[0][2] + cross[1][2] + cross[2][2];

      /* This should already be done.  But just in case, let's do it again */
      stl_calculate_normal(n, facet);
      stl_normalize_vector(n);

      area = 0.5 * (n[0] * sum[0] + n[1] * sum[1] + n[2] * sum[2]);
      return area;
}

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