ray: ray sphere intersection

Author: recp

include/cglm/call/ray.h

@@ -20,7 +20,15 @@ glmc_ray_triangle(vec3   origin,
                   vec3   v1,
                   vec3   v2,
                   float *d);
-    
+
+CGLM_EXPORT
+bool
+glmc_ray_sphere(vec3 origin,
+                vec3 dir,
+                vec4 s,
+                float * __restrict t1,
+                float * __restrict t2);
+
 #ifdef __cplusplus
 }
 #endif

include/cglm/ray.h

@@ -7,12 +7,17 @@
 
 /*
  Functions:
-   CGLM_INLINE bool glm_line_triangle_intersect(vec3   origin,
-                                                vec3   direction,
-                                                vec3   v0,
-                                                vec3   v1,
-                                                vec3   v2,
-                                                float *d);
+   CGLM_INLINE bool glm_ray_triangle(vec3   origin,
+                                     vec3   direction,
+                                     vec3   v0,
+                                     vec3   v1,
+                                     vec3   v2,
+                                     float *d);
+ CGLM_INLINE bool glm_ray_sphere(vec3 origin,
+                                 vec3 dir,
+                                 vec4 s,
+                                 float * __restrict t1,
+                                 float * __restrict t2)
 */
 
 #ifndef cglm_ray_h
@@ -31,7 +36,6 @@
  * @param[in, out] d         distance to intersection
  * @return whether there is intersection
  */
-
 CGLM_INLINE
 bool
 glm_ray_triangle(vec3   origin,
@@ -74,4 +78,70 @@ glm_ray_triangle(vec3   origin,
   return dist > epsilon;
 }
 
+/*!
+ * @brief ray sphere intersection
+ *
+ * @param[in]  origin ray origin
+ * @param[out] dir    normalized ray direction
+ * @param[in]  s      sphere  [center.x, center.y, center.z, radii]
+ * @param[in]  t1     near point1 (closer to origin)
+ * @param[in]  t2     far point2 (farther from origin)
+ */
+CGLM_INLINE
+bool 
+glm_ray_sphere(vec3 origin,
+               vec3 dir,
+               vec4 s,
+               float * __restrict t1,
+               float * __restrict t2) {
+  vec3  dp;
+  float r2, ddp, dpp, dscr, q, tmp, _t1, _t2;
+
+  /* ensure dir is normalized */
+  glm_vec3_sub(s, origin, dp);
+
+  ddp = glm_vec3_dot(dir, dp);
+  dpp = glm_vec3_norm2(dp);
+
+  /* compute the remedy term for numerical stability */
+  glm_vec3_mulsubs(dir, ddp, dp); /* dp: remedy term */
+
+  r2   = s[3] * s[3];
+  dscr = r2 - glm_vec3_norm2(dp);
+
+  if (dscr < 0.0f) {
+    /* no intersection */
+    return false;
+  }
+
+  dscr = sqrtf(dscr);
+  q    = (ddp >= 0.0f) ? (ddp + dscr) : (ddp - dscr);
+
+  /*
+     include Press, William H., Saul A. Teukolsky,
+     William T. Vetterling, and Brian P. Flannery,
+     "Numerical Recipes in C," Cambridge University Press, 1992.
+   */
+  _t1 = q;
+  _t2 = (dpp - r2) / q;
+
+  /* adjust t1 and t2 to ensure t1 is the closer intersection */
+  if (_t1 > _t2) {
+    tmp = _t1;
+    _t1 = _t2;
+    _t2 = tmp;
+  }
+
+  *t1 = _t1;
+  *t2 = _t2;
+
+  /* check if the closest intersection (t1) is behind the ray's origin */
+  if (_t1 < 0.0f && _t2 < 0.0f) {
+    /* both intersections are behind the ray, no visible intersection */
+    return false;
+  }
+
+  return true;
+}
+
 #endif

include/cglm/struct.h

@@ -41,6 +41,7 @@ extern "C" {
 #include "struct/sphere.h"
 #include "struct/curve.h"
 #include "struct/affine2d.h"
+#include "struct/ray.h"
 
 #ifdef __cplusplus
 }

include/cglm/struct/ray.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c), Recep Aslantas.
+ *
+ * MIT License (MIT), http://opensource.org/licenses/MIT
+ * Full license can be found in the LICENSE file
+ */
+
+#ifndef cglms_ray_h
+#define cglms_ray_h
+
+#include "../common.h"
+#include "../types-struct.h"
+#include "../ray.h"
+
+/* api definition */
+#define glms_ray_(NAME) CGLM_STRUCTAPI(ray, NAME)
+
+/*!
+ * @brief Möller–Trumbore ray-triangle intersection algorithm
+ *
+ * @param[in] origin         origin of ray
+ * @param[in] direction      direction of ray
+ * @param[in] v0             first vertex of triangle
+ * @param[in] v1             second vertex of triangle
+ * @param[in] v2             third vertex of triangle
+ * @param[in, out] d         distance to intersection
+ * @return whether there is intersection
+ */
+CGLM_INLINE
+bool
+glms_ray_(triangle)(vec3s  origin,
+                    vec3s  direction,
+                    vec3s  v0,
+                    vec3s  v1,
+                    vec3s  v2,
+                    float *d) {
+  return glm_ray_triangle(origin.raw, direction.raw, v0.raw, v1.raw, v2.raw, d);
+}
+
+/*!
+ * @brief ray sphere intersection
+ *
+ * @param[in]  origin ray origin
+ * @param[out] dir    normalized ray direction
+ * @param[in]  s      sphere  [center.x, center.y, center.z, radii]
+ * @param[in]  t1     near point1 (closer to origin)
+ * @param[in]  t2     far point2 (farther from origin)
+ */
+CGLM_INLINE
+bool
+glms_ray_(sphere)(vec3s origin,
+                  vec3s dir,
+                  vec4s s,
+                  float * __restrict t1,
+                  float * __restrict t2) {
+  return glm_ray_sphere(origin.raw, dir.raw, s.raw, t1, t2);
+}
+
+#endif /* cglms_ray_h */

src/ray.c

@@ -9,5 +9,21 @@ glmc_ray_triangle(vec3   origin,
                   vec3   v1,
                   vec3   v2,
                   float *d) {
-    return glm_ray_triangle(origin, direction, v0, v1, v2, d);
+  return glm_ray_triangle(origin, direction, v0, v1, v2, d);
+}
+
+CGLM_EXPORT
+bool
+glmc_ray_sphere(vec3 origin,
+                vec3 dir,
+                vec4 s,
+                float * __restrict t1,
+                float * __restrict t2) {
+  return glm_ray_sphere(origin, dir, s, t1, t2);
+}
+
+CGLM_EXPORT
+void
+glmc_ray_at(vec3 orig, vec3 dir, float t, vec3 point) {
+  glm_ray_at(orig, dir, t, point);
 }

win/cglm.vcxproj

@@ -253,6 +253,7 @@
     <ClInclude Include="..\include\cglm\struct\plane.h" />
     <ClInclude Include="..\include\cglm\struct\project.h" />
     <ClInclude Include="..\include\cglm\struct\quat.h" />
+    <ClInclude Include="..\include\cglm\struct\ray.h" />
     <ClInclude Include="..\include\cglm\struct\sphere.h" />
     <ClInclude Include="..\include\cglm\struct\vec2-ext.h" />
     <ClInclude Include="..\include\cglm\struct\vec2.h" />

win/cglm.vcxproj.filters

@@ -729,5 +729,8 @@
     <ClInclude Include="..\include\cglm\struct\ivec4.h">
       <Filter>include\cglm\struct</Filter>
     </ClInclude>
+    <ClInclude Include="..\include\cglm\struct\ray.h">
+      <Filter>include\cglm\struct</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>