ray: point along a ray at a parameter t

include/cglm/call/ray.h

@@ -29,6 +29,10 @@ glmc_ray_sphere(vec3 origin,
                 float * __restrict t1,
                 float * __restrict t2);
 
+CGLM_EXPORT
+void
+glmc_ray_at(vec3 orig, vec3 dir, float t, vec3 point);
+
 #ifdef __cplusplus
 }
 #endif

include/cglm/ray.h

@@ -18,6 +18,7 @@
                                  vec4 s,
                                  float * __restrict t1,
                                  float * __restrict t2)
+ CGLM_INLINE void glm_ray_at(vec3 orig, vec3 dir, float t, vec3 point);
 */
 
 #ifndef cglm_ray_h
@@ -144,4 +145,20 @@ glm_ray_sphere(vec3 origin,
   return true;
 }
 
+/*!
+ * @brief point using t by 𝐏(𝑡)=𝐀+𝑡𝐛
+ *
+ * @param[in]  orig  origin of ray
+ * @param[in]  dir   direction of ray
+ * @param[in]  t     parameter
+ * @param[out] point point at t
+ */
+CGLM_INLINE
+void
+glm_ray_at(vec3 orig, vec3 dir, float t, vec3 point) {
+  vec3 dst;
+  glm_vec3_scale(dir, t, dst);
+  glm_vec3_add(orig, dst, point);
+}
+
 #endif

include/cglm/struct/ray.h

@@ -56,4 +56,20 @@ glms_ray_(sphere)(vec3s origin,
   return glm_ray_sphere(origin.raw, dir.raw, s.raw, t1, t2);
 }
 
+/*!
+ * @brief point using t by 𝐏(𝑡)=𝐀+𝑡𝐛
+ *
+ * @param[in]  orig  origin of ray
+ * @param[in]  dir   direction of ray
+ * @param[in]  t     parameter
+ * @returns point point at t
+ */
+CGLM_INLINE
+vec3s
+glms_ray_(at)(vec3s orig, vec3s dir, float t) {
+  vec3s r;
+  glm_ray_at(orig.raw, orig.raw, t, r.raw);
+  return r;
+}
+
 #endif /* cglms_ray_h */