/*

 * texgen.c

 *

 * FUNCTION:

 * texture mapping hack

 *

 * HISTORY:

 * Created by Linas Vepstas April 1994

 * general cleanup December 1995

 */

#ifdef __APPLE__

#include "gle_osx.h"

#endif

#include <stdlib.h>

#include <math.h>

#include <tube.h>

#include "port.h"

#include "tube_gc.h"

/* ======================================================= */

gleGC *_gle_gc = 0x0;

gleGC * gleCreateGC (void) {

   gleGC * retval = (gleGC *) malloc (sizeof (gleGC));

   retval -> bgn_gen_texture = 0x0;

   retval -> n3f_gen_texture = 0x0;

   retval -> n3d_gen_texture = 0x0;

   retval -> v3f_gen_texture = 0x0;

   retval -> v3d_gen_texture = 0x0;

   retval -> end_gen_texture = 0x0;

   retval -> save_bgn_gen_texture = 0x0;

   retval -> save_n3f_gen_texture = 0x0;

   retval -> save_n3d_gen_texture = 0x0;

   retval -> save_v3f_gen_texture = 0x0;

   retval -> save_v3d_gen_texture = 0x0;

   retval -> save_end_gen_texture = 0x0;

   retval -> join_style = TUBE_JN_ANGLE | TUBE_JN_CAP | TUBE_NORM_FACET;

   retval -> ncp = 0;

   retval -> npoints = 0;

   retval -> num_vert = 0;

   retval -> segment_number = 0;

   retval -> segment_length = 0.0;

   retval -> accum_seg_len = 0.0;

   retval -> prev_x = 0.0;

   retval -> prev_y = 0.0;

   return retval;

}

/* ======================================================= */

#define segment_number (_gle_gc -> segment_number)

#define segment_length (_gle_gc -> segment_length)

#define accum_seg_len (_gle_gc -> accum_seg_len)

#define num_vert  (_gle_gc -> num_vert)

#define prev_x  (_gle_gc -> prev_x)

#define prev_y  (_gle_gc -> prev_y)

/* ======================================================= */

static double save_nx = 0.0;

static double save_ny = 0.0;

static double save_nz = 0.0;

static void save_normal (double *v) {

   save_nx = v[0];

   save_ny = v[1];

   save_nz = v[2];

}

/* ======================================================= */

static void bgn_sphere_texgen (int inext, double len) {

   segment_number = inext - 1;

   segment_length = len;

   num_vert = 0;

}

/* ======================================================= */

/* 

 * this routine assumes that the vertex passed in has been normalized

 * (i.e. is of unit length)

 */

/* ARGSUSED3 */

static void sphere_texgen (double x, double y, double z,

                           int jcnt, int which_end) 

{

   double theta, phi;

   /* let phi and theta range fro 0 to 1 */

   phi = 0.5 * atan2 (x, y) / M_PI;

   phi += 0.5;

   theta = 1.0 - acos (z) / M_PI;

   /* if first vertex, merely record the texture coords */

   if (num_vert == 0) {

      prev_x = phi;

      prev_y = theta;

      num_vert ++;

   } else {

      /* if texture coordinates changed radically, wrap them */

      if ((prev_y - theta) > 0.6) {

         theta +=1.0;

      } else if ((prev_y - theta) < -0.6) {

         theta -=1.0;

      } /* else no-op */

      prev_y = theta;

      /* if texture coordinates changed radically, wrap them */

      if ((prev_x - phi) > 0.6) {

         phi +=1.0;

      } else if ((prev_x - phi) < -0.6) {

         phi -=1.0;

      } /* else no-op */

      prev_x = phi;

   }

   T2F_D (phi, theta);

}

/* ======================================================= */

/* mappers */

static void vertex_sphere_texgen_v (double *v, int jcnt, int which_end)  {

   double x = v[0]; double y = v[1]; double z = v[2];

   double r;

   r = 1.0 / sqrt (x*x + y*y + z*z);

   x *= r;

   y *= r;

   z *= r;

   sphere_texgen (x, y, z, jcnt, which_end);

}

/* ARGSUSED */

static void normal_sphere_texgen_v (double *v, int jcnt, int which_end)  {

   sphere_texgen (save_nx, save_ny, save_nz, jcnt, which_end);

}

static void vertex_sphere_model_v (double *v, int jcnt, int which_end) {

   double x = _gle_gc->contour[jcnt][0]; 

   double y = _gle_gc->contour[jcnt][1]; 

   double z = v[2];

   double r;

   r = 1.0 / sqrt (x*x + y*y + z*z);

   x *= r;

   y *= r;

   z *= r;

   sphere_texgen (x, y, z, jcnt, which_end);

}

/* ARGSUSED */

static void normal_sphere_model_v (double *v, int jcnt, int which_end) {

   if (!(_gle_gc -> cont_normal)) return;

   sphere_texgen (_gle_gc->cont_normal[jcnt][0], 

                _gle_gc->cont_normal[jcnt][1], 0.0, jcnt, which_end);

}

/* ======================================================= */

static void bgn_z_texgen (int inext, double len) {

   /* accumulate the previous length */

   accum_seg_len += segment_length;

   /* save current values */

   segment_number = inext - 1;

   segment_length = len;

   /* reset counter on first segment */

   if (1 >= segment_number) accum_seg_len = 0.0;

   num_vert = 0;

}

/* ======================================================= */

/* ARGSUSED2 */

static void cylinder_texgen (double x, double y, double z,

                             int jcnt, int which_end) 

{

   double phi;

   /* let phi and theta range fro 0 to 1 */

   phi = 0.5 * atan2 (x, y) / M_PI;

   phi += 0.5;

   /* if first vertex, merely record the texture coords */

   if (num_vert == 0) {

      prev_x = phi;

      num_vert ++;

   } else {

      /* if texture coordinates changed radically, wrap them */

      if ((prev_x - phi) > 0.6) {

         phi +=1.0;

      } else if ((prev_x - phi) < -0.6) {

         phi -=1.0;

      } /* else no-op */

      prev_x = phi;

   }

   if (FRONT == which_end) {

      T2F_D (phi, accum_seg_len);

   }

   if (BACK == which_end) {

      T2F_D (phi, accum_seg_len + segment_length);

   }

}

/* ======================================================= */

/* mappers */

static void vertex_cylinder_texgen_v (double *v, int jcnt, int which_end) {

   double x = v[0]; double y = v[1]; double z = v[2];

   double r;

   r = 1.0 / sqrt (x*x + y*y);

   x *= r;

   y *= r;

   cylinder_texgen (x, y, z, jcnt, which_end);

}

/* ARGSUSED */

static void normal_cylinder_texgen_v (double *v, int jcnt, int which_end) {

   cylinder_texgen (save_nx, save_ny, save_nz, jcnt, which_end);

}

static void vertex_cylinder_model_v (double *v, int jcnt, int which_end) {

   double x = _gle_gc->contour[jcnt][0]; 

   double y = _gle_gc->contour[jcnt][1]; 

   double z = v[2];

   double r;

   r = 1.0 / sqrt (x*x + y*y);

   x *= r;

   y *= r;

   cylinder_texgen (x, y, z, jcnt, which_end);

}

/* ARGSUSED */

static void normal_cylinder_model_v (double *v, int jcnt, int which_end) {

   if (!(_gle_gc -> cont_normal)) return;

   cylinder_texgen (_gle_gc->cont_normal[jcnt][0], 

                _gle_gc->cont_normal[jcnt][1], 0.0, jcnt, which_end);

}

/* ======================================================= */

/* ARGSUSED1 */

static void flat_texgen (double x, double y, double z,

                             int jcnt, int which_end) 

{

   if (FRONT == which_end) {

      T2F_D (x, accum_seg_len);

   }

   if (BACK == which_end) {

      T2F_D (x, accum_seg_len + segment_length);

   }

}

/* ======================================================= */

static void vertex_flat_texgen_v (double *v, int jcnt, int which_end) {

   flat_texgen (v[0], v[1], v[2], jcnt, which_end);

}

/* ARGSUSED */

static void normal_flat_texgen_v (double *v, int jcnt, int which_end) {

   flat_texgen (save_nx, save_ny, save_nz, jcnt, which_end);

}

static void vertex_flat_model_v (double *v, int jcnt, int which_end) {

   flat_texgen (_gle_gc->contour[jcnt][0], 

                _gle_gc->contour[jcnt][1], v[2], jcnt, which_end);

}

/* ARGSUSED */

static void normal_flat_model_v (double *v, int jcnt, int which_end) {

   if (!(_gle_gc -> cont_normal)) return;

   flat_texgen (_gle_gc->cont_normal[jcnt][0], 

                _gle_gc->cont_normal[jcnt][1], 0.0, jcnt, which_end);

}

/* ======================================================= */

void gleTextureMode (int mode) {

   INIT_GC();

   /* enable textureing by restoring the mode */

   _gle_gc -> bgn_gen_texture = _gle_gc -> save_bgn_gen_texture; 

   _gle_gc -> n3f_gen_texture = _gle_gc -> save_n3f_gen_texture; 

   _gle_gc -> n3d_gen_texture = _gle_gc -> save_n3d_gen_texture; 

   _gle_gc -> v3f_gen_texture = _gle_gc -> save_v3f_gen_texture; 

   _gle_gc -> v3d_gen_texture = _gle_gc -> save_v3d_gen_texture; 

   _gle_gc -> end_gen_texture = _gle_gc -> save_end_gen_texture; 

   switch (mode&GLE_TEXTURE_STYLE_MASK) {

      case GLE_TEXTURE_VERTEX_FLAT:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = vertex_flat_texgen_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_FLAT:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = normal_flat_texgen_v;

         _gle_gc -> n3d_gen_texture = save_normal;

         break;

      case GLE_TEXTURE_VERTEX_MODEL_FLAT:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = vertex_flat_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_MODEL_FLAT:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = normal_flat_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_VERTEX_CYL:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = vertex_cylinder_texgen_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_CYL:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = normal_cylinder_texgen_v;

         _gle_gc -> n3d_gen_texture = save_normal;

         break;

      case GLE_TEXTURE_VERTEX_MODEL_CYL:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = vertex_cylinder_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_MODEL_CYL:

         _gle_gc -> bgn_gen_texture = bgn_z_texgen;

         _gle_gc -> v3d_gen_texture = normal_cylinder_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_VERTEX_SPH:

         _gle_gc -> bgn_gen_texture = bgn_sphere_texgen;

         _gle_gc -> v3d_gen_texture = vertex_sphere_texgen_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_SPH:

         _gle_gc -> bgn_gen_texture = bgn_sphere_texgen;

         _gle_gc -> v3d_gen_texture = normal_sphere_texgen_v;

         _gle_gc -> n3d_gen_texture = save_normal;

         break;

      case GLE_TEXTURE_VERTEX_MODEL_SPH:

         _gle_gc -> bgn_gen_texture = bgn_sphere_texgen;

         _gle_gc -> v3d_gen_texture = vertex_sphere_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      case GLE_TEXTURE_NORMAL_MODEL_SPH:

         _gle_gc -> bgn_gen_texture = bgn_sphere_texgen;

         _gle_gc -> v3d_gen_texture = normal_sphere_model_v;

         _gle_gc -> n3d_gen_texture = 0x0;

         break;

      default:

         break;

   }

   /* disable texturing, and save the mode */

   if (!(mode & GLE_TEXTURE_ENABLE)) {

      _gle_gc -> save_bgn_gen_texture = _gle_gc -> bgn_gen_texture; 

      _gle_gc -> save_n3f_gen_texture = _gle_gc -> n3f_gen_texture; 

      _gle_gc -> save_n3d_gen_texture = _gle_gc -> n3d_gen_texture; 

      _gle_gc -> save_v3f_gen_texture = _gle_gc -> v3f_gen_texture; 

      _gle_gc -> save_v3d_gen_texture = _gle_gc -> v3d_gen_texture; 

      _gle_gc -> save_end_gen_texture = _gle_gc -> end_gen_texture; 

      _gle_gc -> bgn_gen_texture = 0x0;

      _gle_gc -> n3f_gen_texture = 0x0;

      _gle_gc -> n3d_gen_texture = 0x0;

      _gle_gc -> v3f_gen_texture = 0x0;

      _gle_gc -> v3d_gen_texture = 0x0;

      _gle_gc -> end_gen_texture = 0x0;

   }

}

/* ================== END OF FILE ========================= */