star-3d

Surface structuring for efficient 3D geometric queries
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s3d_sphere.h (2562B)

      1 /* Copyright (C) 2015-2023, 2026 |Méso|Star> (contact@meso-star.com)
      2  *
      3  * This file is part of Star-3D.
      4  *
      5  * Star-3D 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  * Star-3D 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 Star-3D. If not, see <http://www.gnu.org/licenses/>. */
     17 
     18 #ifndef S3D_SPHERE_H
     19 #define S3D_SPHERE_H
     20 
     21 #include "s3d_c.h"
     22 
     23 #include <rsys/ref_count.h>
     24 #include <rsys/float3.h>
     25 
     26 struct sphere {
     27   float pos[3];
     28   float radius;
     29   struct s3d_device* dev;
     30   struct hit_filter filter;
     31   ref_T ref;
     32 };
     33 
     34 extern LOCAL_SYM res_T
     35 sphere_create
     36   (struct s3d_device* dev,
     37    struct sphere** sphere);
     38 
     39 extern LOCAL_SYM void
     40 sphere_ref_get
     41   (struct sphere* sphere);
     42 
     43 extern LOCAL_SYM void
     44 sphere_ref_put
     45   (struct sphere* sphere);
     46 
     47 static INLINE int
     48 sphere_is_degenerated(const struct sphere* sphere)
     49 {
     50   ASSERT(sphere);
     51   return sphere->radius < 0;
     52 }
     53 
     54 static INLINE void
     55 sphere_compute_aabb
     56   (const struct sphere* sphere,
     57    float lower[3],
     58    float upper[3])
     59 {
     60   ASSERT(sphere && lower && upper);
     61   if(sphere_is_degenerated(sphere)) {
     62     f3_splat(lower, FLT_MAX);
     63     f3_splat(upper,-FLT_MAX);
     64   } else {
     65     f3_subf(lower, sphere->pos, sphere->radius);
     66     f3_addf(upper, sphere->pos, sphere->radius);
     67   }
     68 }
     69 
     70 static INLINE float
     71 sphere_compute_area(const struct sphere* sphere)
     72 {
     73   float r;
     74   ASSERT(sphere);
     75   r = sphere->radius;
     76   return (float)(4*PI*r*r);
     77 }
     78 
     79 static INLINE float
     80 sphere_compute_volume(const struct sphere* sphere)
     81 {
     82   float r;
     83   ASSERT(sphere);
     84   r = sphere->radius;
     85   return (float)(4*PI*r*r*r/3);
     86 }
     87 
     88 static FINLINE void
     89 sphere_normal_to_uv(const float normal[3], float uv[2])
     90 {
     91   float u, v, cos_theta;
     92   ASSERT(normal && uv && f3_is_normalized(normal));
     93 
     94   cos_theta = normal[2];
     95 
     96   v = (1.f - cos_theta) * 0.5f;
     97   if(absf(cos_theta) == 1) {
     98     u = 0;
     99   } else if(eq_epsf(normal[0], 0.f, 1.e-6f)) {
    100     u = normal[1] > 0 ? 0.25f : 0.75f;
    101   } else {
    102     double phi = atan2f(normal[1], normal[0]); /* phi in [-PI, PI] */
    103     if(phi < 0) phi = 2*PI + phi; /* phi in [0, 2PI] */
    104     u = (float)(phi / (2*PI));
    105   }
    106   uv[0] = u;
    107   uv[1] = v;
    108 }
    109 
    110 #endif /* S3D_SPHERE_H */