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 int ray_object(const cgm_ray *ray, const struct object *obj, struct rayhit *hit)
  21 {
  22         struct csghit csghit;
  23
  24         if(!ray_object_csg(ray, obj, &csghit)) {
  25                 return 0;
  26         }
  27         if(hit) {
  28                 *hit = csghit.ivlist[0].a;
  29         }
  30         return 1;
  31 }
  32
  33 int ray_object_csg(const cgm_ray *ray, const struct object *obj, struct csghit *hit)
  34 {
  35         int i, res;
  36         cgm_ray localray = *ray;
  37
  38         cgm_rmul_mr(&localray, obj->inv_xform);
  39
  40         switch(obj->type) {
  41         case OBJ_SPHERE:
  42                 res = ray_sphere(ray, (const struct sphere*)obj, hit);
  43                 break;
  44
  45         default:
  46                 res = 0;
  47         }
  48
  49         if(res && hit) {
  50                 for(i=0; i<hit->ivcount; i++) {
  51                         cgm_vmul_m4v3(&hit->ivlist[i].a.pos, obj->xform);
  52                         cgm_vmul_m3v3(&hit->ivlist[i].a.norm, obj->xform);
  53                         cgm_vmul_m4v3(&hit->ivlist[i].b.pos, obj->xform);
  54                         cgm_vmul_m3v3(&hit->ivlist[i].b.norm, obj->xform);
  55                 }
  56         }
  57         return res;
  58 }
  59
  60 int ray_sphere(const cgm_ray *ray, const struct sphere *sph, struct csghit *hit)
  61 {
  62         int i;
  63         float a, b, c, d, sqrt_d, t1, t2;/*, invrad;*/
  64         struct rayhit *rhptr;
  65
  66         a = cgm_vdot(&ray->dir, &ray->dir);
  67         b = 2.0f * ray->dir.x * (ray->origin.x - sph->pos.x) +
  68                 2.0f * ray->dir.y * (ray->origin.y - sph->pos.y) +
  69                 2.0f * ray->dir.z * (ray->origin.z - sph->pos.z);
  70         c = cgm_vdot(&sph->pos, &sph->pos) + cgm_vdot(&ray->origin, &ray->origin) +
  71                 cgm_vdot(&sph->pos, &ray->origin) * -2.0f - sph->rad * sph->rad;
  72
  73         if((d = b * b - 4.0 * a * c) < 0.0) return 0;
  74
  75         sqrt_d = sqrt(d);
  76         t1 = (-b + sqrt_d) / (2.0 * a);
  77         t2 = (-b - sqrt_d) / (2.0 * a);
  78
  79         if((t1 < 1e-6f && t2 < 1e-6f) || (t1 > 1.0f && t2 > 1.0f)) {
  80                 return 0;
  81         }
  82
  83         if(hit) {
  84                 if(t1 < 1e-6f || t1 > 1.0f) {
  85                         t1 = t2;
  86                 } else if(t2 < 1e-6f || t2 > 1.0f) {
  87                         t2 = t1;
  88                 }
  89                 if(t2 < t1) {
  90                         float tmp = t1;
  91                         t1 = t2;
  92                         t2 = tmp;
  93                 }
  94
  95                 hit->ivcount = 1;
  96                 hit->ivlist[0].a.t = t1;
  97                 hit->ivlist[0].b.t = t2;
  98                 /*invrad = 1.0f / sph->rad;*/
  99
 100                 rhptr = &hit->ivlist[0].a;
 101                 for(i=0; i<2; i++) {
 102                         cgm_raypos(&rhptr->pos, ray, rhptr->t);
 103                         rhptr->norm = rhptr->pos;
 104                         cgm_vnormalize(&rhptr->norm);
 105                         /*rhptr->norm.x = rhptr->pos.x * invrad;
 106                         rhptr->norm.y = rhptr->pos.y * invrad;
 107                         rhptr->norm.z = rhptr->pos.z * invrad;*/
 108                         rhptr->uv.x = (atan2(rhptr->norm.z, rhptr->norm.x) + CGM_PI) / (2.0 * CGM_PI);
 109                         rhptr->uv.y = acos(rhptr->norm.y) / CGM_PI;
 110                         rhptr->obj = (struct object*)sph;
 111                         rhptr = &hit->ivlist[0].b;
 112                 }
 113         }
 114         return 1;
 115 }
 116
 117 int ray_csg(const cgm_ray *ray, const struct csgnode *csg, struct csghit *hit)
 118 {
 119         return 0;
 120 }
 121
 122 float ray_object_dist(const cgm_ray *ray, const struct object *obj)
 123 {
 124         /*struct rayhit hit;*/
 125         cgm_vec3 norm, pvec;
 126
 127         /*if(ray_object(ray, obj, &hit)) {
 128                 return cgm_vdist(&hit.pos, &ray->origin);
 129         }*/
 130
 131         /* if we can't hit the object for some reason, fallback to computing the
 132          * distance of obj->pos from the plane perpendicular to the ray at the origin
 133          */
 134         norm = ray->dir;
 135         /*cgm_vnormalize(&norm);*/
 136         pvec = obj->pos;
 137         cgm_vsub(&pvec, &ray->origin);
 138         return cgm_vdot(&pvec, &norm);
 139 }