star-cad

commit db7bfdf1058db9ac8b05308281a218fdd679ac20
parent 58e54e362bc4ad48db117bebce1d928d0ed442e3
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Wed,  9 Jul 2025 11:12:04 +0200

Change API for get_closest_point

Add an optional argument to return the underlying geometry of the
closest point.

The tests are not updated yet.

Diffstat:
M
src/scad.h
 | 
10
+++++++---
M
src/scad_geometry.c
 | 
20
++++++++++++++++++--

2 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/src/scad.h b/src/scad.h
@@ -394,14 +394,18 @@ scad_geometry_get_centerofmass
   (struct scad_geometry* geometry,
    double* center);
 
-/* Get the `closest- point on geometry `geometry' from point `from' and its
- * `distance'. */
+/* Get the `closest' point on geometry `geometry' from point `from'.
+ * Return the `closest' point and its `distance'.
+ * The underlying 2D geometry on wich the closest point is located is returned
+ * as a new geometry in `closest_geom' if it is not NULL.
+ * If `geometry' is 3D, this underlying geometry is (a part of) its boundary. */
 SCAD_API res_T
 scad_geometry_get_closest_point
   (struct scad_geometry* geometry,
    const double from[3],
    double closest[3],
-   double* distance);
+   double* distance,
+   struct scad_geometry** closest_geom); /* Can be NULL */
 
 /* Get the normal of the geometry `geometry' at position `p'.
  * The normal is set in `N' and the underlying 2D entity to which `p' belongs is
diff --git a/src/scad_geometry.c b/src/scad_geometry.c
@@ -726,7 +726,8 @@ scad_geometry_get_closest_point
   (struct scad_geometry* geom,
    const double from[3],
    double closest[3],
-   double* closest_distance)
+   double* closest_distance,
+   struct scad_geometry** out_geometry)
 {
   res_T res = RES_OK;
   size_t i = 0;
@@ -737,7 +738,7 @@ scad_geometry_get_closest_point
   struct darray_int tags;
   const int* data = NULL;
   size_t sz = 0;
-  int initialized = 0;
+  int initialized = 0, min_tag = -1;
 
   if(!geom || !from || !closest) {
     res = RES_BAD_ARG;
@@ -769,6 +770,7 @@ scad_geometry_get_closest_point
     ASSERT(coord_n == 3);
     d = d3_len(d3_sub(tmp, from, coord));
     if(d < min_d) {
+      min_tag = tag;
       min_d = d;
       d3_set(min, coord);
     }
@@ -776,8 +778,22 @@ scad_geometry_get_closest_point
     gmshFree(pcoord);
     coord = pcoord = NULL;
   }
+  ASSERT(min_tag != -1);
   d3_set(closest, min);
   *closest_distance = min_d;
+  if(out_geometry) {
+    ERR(geometry_create(out_geometry));
+    (*out_geometry)->gmsh_dimTags =
+      MEM_ALLOC(dev->allocator, 2 * sizeof(*(*out_geometry)->gmsh_dimTags));
+    if(!(*out_geometry)->gmsh_dimTags) {
+      res = RES_MEM_ERR;
+      goto error;
+    }
+    (*out_geometry)->gmsh_dimTags_n = 2;
+    (*out_geometry)->gmsh_dimTags[0] = 2;
+    (*out_geometry)->gmsh_dimTags[1] = min_tag;
+    ERR(device_register_tags(*out_geometry));
+  }
 
 exit:
   if(initialized) darray_int_release(&tags);