git.mutantstargoat.com Git - retroray/blob - src/rt.c

   1 /*
   2 RetroRay - integrated standalone vintage modeller/renderer
   3 Copyright (C) 2023  John Tsiombikas <nuclear@mutantstargoat.com>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, either version 3 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <https://www.gnu.org/licenses/>.
  17 */
  18 #include "rt.h"
  19
  20
  21 int ray_object(const cgm_ray *ray, const struct object *obj, struct csghit *hit)
  22 {
  23         int i, res;
  24         cgm_ray localray = *ray;
  25
  26         cgm_rmul_mr(&localray, obj->inv_xform);
  27
  28         switch(obj->type) {
  29         case OBJ_SPHERE:
  30                 res = ray_sphere(ray, (const struct sphere*)obj, hit);
  31                 break;
  32
  33         default:
  34                 res = 0;
  35         }
  36
  37         if(res && hit) {
  38                 for(i=0; i<hit->ivcount; i++) {
  39                         cgm_vmul_m4v3(&hit->ivlist[i].a.pos, obj->xform);
  40                         cgm_vmul_m3v3(&hit->ivlist[i].a.norm, obj->xform);
  41                         cgm_vmul_m4v3(&hit->ivlist[i].b.pos, obj->xform);
  42                         cgm_vmul_m3v3(&hit->ivlist[i].b.norm, obj->xform);
  43                 }
  44         }
  45         return res;
  46 }
  47
  48 int ray_sphere(const cgm_ray *ray, const struct sphere *sph, struct csghit *hit)
  49 {
  50         int i;
  51         float a, b, c, d, sqrt_d, t1, t2, invrad;
  52         struct rayhit *rhptr;
  53
  54         a = cgm_vdot(&ray->dir, &ray->dir);
  55         b = 2.0f * ray->dir.x * (ray->origin.x - sph->pos.x) +
  56                 2.0f * ray->dir.y * (ray->origin.y - sph->pos.y) +
  57                 2.0f * ray->dir.z * (ray->origin.z - sph->pos.z);
  58         c = cgm_vdot(&sph->pos, &sph->pos) + cgm_vdot(&ray->origin, &ray->origin) +
  59                 cgm_vdot(&sph->pos, &ray->origin) * -2.0f - sph->rad * sph->rad;
  60
  61         if((d = b * b - 4.0 * a * c) < 0.0) return 0;
  62
  63         sqrt_d = sqrt(d);
  64         t1 = (-b + sqrt_d) / (2.0 * a);
  65         t2 = (-b - sqrt_d) / (2.0 * a);
  66
  67         if((t1 < 1e-6f && t2 < 1e-6f) || (t1 > 1.0f && t2 > 1.0f)) {
  68                 return 0;
  69         }
  70
  71         if(hit) {
  72                 if(t1 < 1e-6f || t1 > 1.0f) {
  73                         t1 = t2;
  74                 } else if(t2 < 1e-6f || t2 > 1.0f) {
  75                         t2 = t1;
  76                 }
  77                 if(t2 < t1) {
  78                         float tmp = t1;
  79                         t1 = t2;
  80                         t2 = tmp;
  81                 }
  82
  83                 hit->ivcount = 1;
  84                 hit->ivlist[0].a.t = t1;
  85                 hit->ivlist[0].b.t = t2;
  86                 invrad = 1.0f / sph->rad;
  87
  88                 rhptr = &hit->ivlist[0].a;
  89                 for(i=0; i<2; i++) {
  90                         cgm_raypos(&rhptr->pos, ray, rhptr->t);
  91                         rhptr->norm.x = rhptr->pos.x * invrad;
  92                         rhptr->norm.y = rhptr->pos.y * invrad;
  93                         rhptr->norm.z = rhptr->pos.z * invrad;
  94                         rhptr->uv.x = (atan2(rhptr->norm.z, rhptr->norm.x) + CGM_PI) / (2.0 * CGM_PI);
  95                         rhptr->uv.y = acos(rhptr->norm.y) / CGM_PI;
  96                         rhptr->obj = (struct object*)sph;
  97                         rhptr = &hit->ivlist[0].b;
  98                 }
  99         }
 100         return 1;
 101 }
 102
 103 int ray_csg(const cgm_ray *ray, const struct csgnode *csg, struct csghit *hit)
 104 {
 105         return 0;
 106 }