/* General-purpose geometric models. */
/* Last edited on 2020-10-03 20:34:19 by jstolfi */

#ifndef gmo_H
#define gmo_H

#include <quad.h>
#include <bool.h>
#include <frgb.h>
#include <hr3.h>

#include <gmo_opto.h>

/* A geometric model {gmo_t} is the union of solid /items/.  Each item is
  described by one or more /knots/.  Each knot has a point, a radius, a
  a tangent plane, and an /opto/ (an object that defines its optical 
  properties; basically a BRDF). */

typedef enum 
  { gmo_item_kind_DOT =   0,
    gmo_item_kind_SLUG =  1,
    gmo_item_kind_TRI =   2,
    gmo_item_kind_COUNT = 3
  } gmo_item_kind_t;
  /* King of a plottable item in a geometric model.  See
    {gmo_{xxx}_t} for a description of items
    with kind {gmo_item_kind_{XXX}}.  The kind {gmo_item_kind_COUNT}
    is not a valid kind, only the limit for {for} loops and such. */
 
typedef void *gmo_item_addr_t;
  /* Pointer to a plottable item; actually to a {gmo_dot_t},
    {gmo_slug_t}, or {gmo_tri_t}. */
 
typedef struct gmo_t 
   { int npoints;             /* Number of points. */
     hr3_point_t *point;      /* {point[0..npoints-1]} are homog coords of key points. */
     int nplanes;             /* Number of planes. */
     hr3_plane_t *plane;      /* {plane[0..nplanes-1]} are homog coeffs of key planes. */
     int noptos;              /* Number of optos. */
     gmo_opto_t *opto;        /* Opto list. */
     int nknots;              /* Number of knots. */
     struct gmo_knot_t *knot; /* Knot list. */
     int nitems;              /* Number of plottable items. */
     gmo_item_kind_t *iknd;   /* {kind[0..nitems-1]} are the item types. */
     gmo_item_addr_t *item;   /* {item[0..nitems-1]} are the addresses of the items. */
  } gmo_t;

typedef int gmo_knot_ix_t;
typedef int gmo_point_ix_t;
typedef int gmo_plane_ix_t;
typedef int gmo_color_ix_t;
typedef int gmo_opto_ix_t;
typedef int gmo_item_ix_t;
  /* Indices into {knot}, {point}, {plane}, {color}, {opto}, and {item} tables 
    of a {gmo_t} model. */
    
/* KNOTS */
  
typedef struct gmo_knot_t
  { gmo_point_ix_t pt;   /* Position (index into {point} list) or -1 if none. */
    gmo_point_ix_t tp;   /* Tangent plane (index into {plane} list) or -1 if none. */
    gmo_opto_ix_t opto;  /* Optical operator (index into {opto} list). */
    float radius;        /* Radius/thickness. */
  } gmo_knot_t; 
  /* A `knot' is an infinitesimal surface element, that is,
    a point of space, a tangent plane, a radius, and an opto. */

/* ITEM KINDS */
  
typedef struct gmo_item_dot_t 
  { gmo_knot_ix_t kn;
  } gmo_item_dot_t; 
  /* A `dot' element, that is, a small sphere. The knot specifies
    the center, radius, and opto of the sphere.
    The tangent plane of the knot is irrelevant. */

typedef struct gmo_item_slug_t 
  { gmo_knot_ix_t kn[2]; 
  } gmo_item_slug_t;
  /* A `slug' item, that is, a sphere-capped cone. The knots specify
    the centers, radii, and optos of the two end-spheres.
    The tangent planes of the knots are irrelevant. */

typedef struct gmo_item_tri_t 
  { gmo_knot_ix_t kn[3]; /* Positions, optos, radii and tangent planes of corners. */
  } gmo_item_tri_t;
  /* A `tri' element, that is, a triangle with rounded edges and corners.
    The knots specify the centers, radii, and optos of the three end-spheres.
    The tangent planes of the knots are irrelevant. */

/* I/O */

void gmo_write(FILE *wr, gmo_t *P);
  /* Writes a description of {P} {wr}, in a format that can be
    read back with {gmo_read} below.. */
  
gmo_t *gmo_read(FILE *rd);
  /* Reads a plot list {P} from the reader {rd}. Assumes the
    format used by {Write} above. */

/* ITEM ENUMERATION */

typedef bool_t gmo_item_dot_proc_t(gmo_item_ix_t ix, gmo_item_dot_t *t);
typedef bool_t gmo_item_slug_proc_t(gmo_item_ix_t ix, gmo_item_slug_t *t);
typedef bool_t gmo_item_tri_proc_t(gmo_item_ix_t ix, gmo_item_tri_t *t);
  /* Client procedures for {gmo_enum_items}. */

gmo_item_ix_t gmo_enum_items
  ( gmo_t *P, 
    gmo_item_dot_proc_t visit_dot,
    gmo_item_slug_proc_t visit_slug,
    gmo_item_tri_proc_t visit_tri
  );
  /* Enumerates all items of {P} in order, calling the appropriate {visit_XXX}
    procedure on each. If any of the procedures returns {TRUE}, stops
    the enumeration and returns that element's index. Otherwise
    returns -1. */

/* INPUT/OUTPUT */

gmo_item_kind_t gmo_item_kind_from_char(char c);
char gmo_item_kind_to_char(gmo_item_kind_t iknd);

#endif