rngrd

commit 496e9c717254aff60263404becb78ce4e1b8ca1c
parent 1279c611af4b8bfc8a0b75d097c8f39e7d23fc9e
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Fri, 22 May 2026 14:21:15 +0200

Add the API function for finding the closest point

Like the ray-tracing function, it serves as an interface to the Star-3D
library used to partition the ground geometry.

Diffstat:
M
config.mk
 | 
2
+-
M
src/rngrd.h
 | 
23
+++++++++++++++++++++++
M
src/rngrd_mesh.c
 | 
65
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------

3 files changed, 82 insertions(+), 8 deletions(-)
diff --git a/config.mk b/config.mk
@@ -1,4 +1,4 @@
-VERSION = 0.1.1
+VERSION = 0.2.0
 PREFIX = /usr/local
 
 LIB_TYPE = SHARED
diff --git a/src/rngrd.h b/src/rngrd.h
@@ -97,6 +97,23 @@ struct rngrd_trace_ray_args {
 static const struct rngrd_trace_ray_args RNGRD_TRACE_RAY_ARGS_DEFAULT =
   RNGRD_TRACE_RAY_ARGS_DEFAULT__;
 
+struct rngrd_closest_point_args {
+  double position[3];
+  double radius; /* Search radius around the position */
+
+  s3d_hit_filter_function_T filter; /* NULL <=> Return closest triangle */
+  void* filter_data; /* User data send to the filter function */
+};
+#define RNGRD_CLOSEST_POINT_ARGS_DEFAULT__ {                                   \
+  {0,0,0}, /* Position */                                                      \
+  DBL_MAX, /* Radius */                                                        \
+                                                                               \
+  NULL, /* Filter function */                                                  \
+  NULL /* Filter data */                                                       \
+}
+static const struct rngrd_closest_point_args
+RNGRD_CLOSEST_POINT_ARGS_DEFAULT = RNGRD_CLOSEST_POINT_ARGS_DEFAULT__;
+
 struct rngrd_create_bsdf_args {
   struct s3d_primitive prim; /* Surface primitive to query */
   double barycentric_coords[3]; /* Position into and relative to `prim' */
@@ -151,6 +168,12 @@ rngrd_trace_ray
    struct s3d_hit* hit);
 
 RNGRD_API res_T
+rngrd_closest_point
+  (const struct rngrd* ground,
+   struct rngrd_closest_point_args* args,
+   struct s3d_hit* hit);
+
+RNGRD_API res_T
 rngrd_create_bsdf
   (struct rngrd* ground,
    const struct rngrd_create_bsdf_args* args,
diff --git a/src/rngrd_mesh.c b/src/rngrd_mesh.c
@@ -31,6 +31,14 @@
 #include <rsys/float2.h>
 #include <rsys/float3.h>
 
+struct filter_args {
+  struct s3d_hit hit;
+
+  s3d_hit_filter_function_T func; /* NULL <=> Stop RT at 1st hit triangle */
+  void* context; /* User data send to the filter function */
+};
+static const struct filter_args FILTER_ARGS_NULL = {S3D_HIT_NULL, NULL, NULL};
+
 /*******************************************************************************
  * Helper functions
  ******************************************************************************/
@@ -129,7 +137,7 @@ mesh_filter
    void* ray_data,
    void* filter_data)
 {
-  const struct rngrd_trace_ray_args* ray_args = ray_data;
+  const struct filter_args* filter = ray_data;
   (void)filter_data;
 
   /* Internally, Star-3D relies on Embree which, due to numerical imprecision,
@@ -138,18 +146,18 @@ mesh_filter
   if(hit->distance <= ray_range[0] || hit->distance >= ray_range[1])
     return 1;
 
-  if(!ray_args) /* Nothing more to do */
+  if(!filter) /* Nothing more to do */
     return 0;
 
   /* Discard this intersection */
-  if(self_hit(hit, ray_org, ray_dir, ray_range, &ray_args->hit_from))
+  if(self_hit(hit, ray_org, ray_dir, ray_range, &filter->hit))
     return 1;
 
-  if(!ray_args->filter) /* No user-defined filter functions */
+  if(!filter->func) /* No user-defined filter functions */
     return 0;
 
-  return ray_args->filter /* Invoke user-defined filtering */
-    (hit, ray_org, ray_dir, ray_range, ray_args->filter_data, filter_data);
+  return filter->func /* Invoke user-defined filtering */
+    (hit, ray_org, ray_dir, ray_range, filter->context, filter_data);
 }
 
 static void
@@ -269,6 +277,7 @@ rngrd_trace_ray
    struct rngrd_trace_ray_args* args,
    struct s3d_hit* hit)
 {
+  struct filter_args filter = FILTER_ARGS_NULL;
   float org[3];
   float dir[3];
   float range[2];
@@ -283,9 +292,13 @@ rngrd_trace_ray
   f3_set_d3(dir, args->ray_dir);
   f2_set_d2(range, args->ray_range);
 
+  filter.hit = args->hit_from;
+  filter.func = args->filter;
+  filter.context = args->filter_data;
+
   *hit = S3D_HIT_NULL;
 
-  res = s3d_scene_view_trace_ray(ground->s3d_view, org, dir, range, args, hit);
+  res = s3d_scene_view_trace_ray(ground->s3d_view, org, dir, range, &filter, hit);
   if(res != RES_OK) {
     log_err(ground,
       "%s: error tracing ray "
@@ -300,6 +313,44 @@ error:
   goto exit;
 }
 
+res_T
+rngrd_closest_point
+  (const struct rngrd* ground,
+   struct rngrd_closest_point_args* args,
+   struct s3d_hit* hit)
+{
+  struct filter_args filter = FILTER_ARGS_NULL;
+  float pos[3];
+  float radius;
+  res_T res = RES_OK;
+
+  if(!ground || !args || !hit) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  f3_set_d3(pos, args->position);
+  radius = (float)args->radius;
+  filter.func = args->filter;
+  filter.context = args->filter_data;
+
+  *hit = S3D_HIT_NULL;
+
+  res = s3d_scene_view_closest_point(ground->s3d_view, pos, radius, &filter, hit);
+  if(res != RES_OK) {
+    log_err(ground,
+      "%s: error finding the closest point "
+      "(position = %g, %g, %g; radius = %g)\n",
+      FUNC_NAME, SPLIT3(pos), radius);
+    goto error;
+  }
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
 /*******************************************************************************
  * Local function
  ******************************************************************************/