/*
 * Program to generate a simple model designed for finding an edge in a
 *  model.  The paradigm is, you run this and mergemodel it with the
 *  original model; the result then has the relevant lines marked with
 *  arrowheadish triangles.
 *
 * Usage:
 *	$0 x1 y1 z1 x2 y2 z2 size r g b
 *  where one end of the segment to be called out is (x1,y1,z1) and the
 *  other is (x2,y2,z2).  size is the point-to-back size of the
 *  arrowheads; their aspect ratio is fixed, with the back end being
 *  10% of the length.  r, g, and b are an RGB triple (floating point
 *  0-1) of the colour of the material to be generated.
 *
 * Each triangle is generated twice, once facing each way, so it's sure
 *  to be visible even with backface removal turned on.
 *
 * The resulting model appears on stdout.
 */

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

extern const char *__progname;

#include "3d.h"
#include "model.h"

static PT3 e1;
static PT3 e2;
static double size;
static double r;
static double g;
static double b;
static MODEL *m;

static XYZ pt3_to_xyz(PT3 p)
{
 return((XYZ){.x=p.x,.y=p.y,.z=p.z});
}

static PT3 xyz_to_pt3(XYZ p)
{
 return((PT3){.x=p.x,.y=p.y,.z=p.z});
}

static double double_arg(const char *arg, const char *what)
{
 char *ep;
 double v;

 v = strtod(arg,&ep);
 if (ep == arg)
  { fprintf(stderr,"%s: %s: no number found for %s\n",__progname,arg,what);
    exit(1);
  }
 if (*ep)
  { fprintf(stderr,"%s: %s: junk after %s\n",__progname,arg,what);
    exit(1);
  }
 return(v);
}

static void gen_triangle(POINT *p, PT3 back, PT3 side, int mx)
{
 PT3 tip;
 PT3 h1;
 PT3 h2;
 POINT *p1;
 POINT *p2;
 LOCATION *l1;
 LOCATION *l2;
 TRIANGLE *t;

 tip = xyz_to_pt3(get_location(m,p->loc)->l);
 back = smul3(size,back);
 side = smul3(size*.1,side);
 h1 = add3(tip,add3(back,side));
 h2 = add3(tip,sub3(back,side));
 l1 = get_location(m,new_location(m));
 l1->l = pt3_to_xyz(h1);
 p1 = get_point(m,new_point(m));
 p1->loc = l1->inx;
 p1->type = PT_CORNER;
 l2 = get_location(m,new_location(m));
 l2->l = pt3_to_xyz(h2);
 p2 = get_point(m,new_point(m));
 p2->loc = l2->inx;
 p2->type = PT_CORNER;
 t = get_triangle(m,new_triangle(m));
 t->material = mx;
 t->corner[0] = p->inx;
 t->corner[1] = p1->inx;
 t->corner[2] = p2->inx;
 t = get_triangle(m,new_triangle(m));
 t->material = mx;
 t->corner[0] = p->inx;
 t->corner[1] = p2->inx;
 t->corner[2] = p1->inx;
}

int main(int, char **);
int main(int ac, char **av)
{
 PT3 v;
 PT3 x1;
 PT3 x2;
 MATERIAL *s;
 LOCATION *l;
 POINT *p;
 OBJECT *o;
 double d;
 int i;

 if (ac != 11)
  { fprintf(stderr,"Usage: %s x1 y1 z2 x2 y2 z2 size r g b\n",__progname);
    exit(1);
  }
 e1.x = double_arg(av[1],"endpoint 1 X");
 e1.y = double_arg(av[2],"endpoint 1 Y");
 e1.z = double_arg(av[3],"endpoint 1 Z");
 e2.x = double_arg(av[4],"endpoint 2 X");
 e2.y = double_arg(av[5],"endpoint 2 Y");
 e2.z = double_arg(av[6],"endpoint 2 Z");
 size = double_arg(av[7],"size");
 if (size < 0)
  { fprintf(stderr,"%s: size %g out of range\n",__progname,size);
    exit(1);
  }
 r = double_arg(av[8],"red value");
 g = double_arg(av[9],"green value");
 b = double_arg(av[10],"blue value");
 if ((r < 0) || (r > 1) || (g < 0) || (g > 1) || (b < 0) || (b > 1))
  { fprintf(stderr,"%s: RGB triple (%g,%g,%g) out of range\n",__progname,r,g,b);
    exit(1);
  }
 v = unit3(sub3(e2,e1));
 d = fabs(v.x);
 x1 = (PT3){.x=1,.y=0,.z=0};
 if (fabs(v.y) < d)
  { d = fabs(v.y);
    x1 = (PT3){.x=0,.y=1,.z=0};
  }
 if (fabs(v.z) < d)
  { d = fabs(v.z);
    x1 = (PT3){.x=0,.y=0,.z=1};
  }
 x1 = unit3(sub3(x1,smul3(dot3(v,x1),v)));
 x2 = cross(v,x1);
 m = new_model();
 s = get_material(m,new_material(m));
 s->name = strdup("arrows");
 s->selflum = (RGB){.r=r,.g=g,.b=b};
 s->reflect = (RGB){0,0,0};
 s->spec_exp = 1;
 s->spec_mul = 0;
 l = get_location(m,new_location(m));
 l->l = pt3_to_xyz(e1);
 p = get_point(m,new_point(m));
 p->loc = l->inx;
 p->type = PT_CORNER;
 gen_triangle(p,smul3(-1,v),x1,s->inx);
 gen_triangle(p,smul3(-1,v),x2,s->inx);
 gen_triangle(p,x1,x2,s->inx);
 gen_triangle(p,x2,x1,s->inx);
 gen_triangle(p,smul3(-1,x1),x2,s->inx);
 gen_triangle(p,smul3(-1,x2),x1,s->inx);
 l = get_location(m,new_location(m));
 l->l = pt3_to_xyz(e2);
 p = get_point(m,new_point(m));
 p->loc = l->inx;
 p->type = PT_CORNER;
 gen_triangle(p,v,x1,s->inx);
 gen_triangle(p,v,x2,s->inx);
 gen_triangle(p,x1,x2,s->inx);
 gen_triangle(p,x2,x1,s->inx);
 gen_triangle(p,smul3(-1,x1),x2,s->inx);
 gen_triangle(p,smul3(-1,x2),x1,s->inx);
 o = get_object(m,new_object(m));
 o->ntriangles = n_triangles(m);
 o->triangles = malloc(o->ntriangles*sizeof(int));
 for (i=o->ntriangles;i>=0;i--) o->triangles[i] = i;
 save_model(m,stdout);
 free_model(m);
 exit(0);
}