stardis-solver

commit 4282ebe01e3f81e7c81884ee52364408d1e37e88
parent b60bf6956299d590e56a790962d69907d025ca28
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Mon, 23 Aug 2021 15:12:24 +0200

Remove zealous geometric error detection

Querying the current medium could return an error if the position was
near a primitive. Previously, if up to 10 tries failed to find a
surface, an error was reported. This arbitrary threshold was very small
since, for instance, in 3D, it amounted to looking for an intersection
between the point considered and at most 10 positions on 4 different
triangles. It was too careful because the 4 tested triangles could
present the same numerical problem when tracing a ray towards them. This
commit removes this criterion since the geometric problem that it was
dealing with is detected elsewhere without an arbitrary threshold on the
number of primitives tested.

Diffstat:
M
src/sdis_scene_Xd.h
 | 
43
+++++++++++++++----------------------------

1 file changed, 15 insertions(+), 28 deletions(-)
diff --git a/src/sdis_scene_Xd.h b/src/sdis_scene_Xd.h
@@ -1033,8 +1033,6 @@ XD(scene_get_medium)
 {
   struct sdis_medium* medium = NULL;
   size_t iprim, nprims;
-  size_t nfailures = 0;
-  const size_t max_failures = 10;
   float P[DIM];
   /* Range of the parametric coordinate into which positions are challenged */
 #if DIM == 2
@@ -1089,23 +1087,13 @@ XD(scene_get_medium)
       fX(normalize)(dir, fX(sub)(dir, attr.value, P));
       SXD(scene_view_trace_ray(scn->sXd(view), P, dir, range, NULL, &hit));
 
-      /* Unforeseen error. One has to intersect a primitive ! */
-      if(SXD_HIT_NONE(&hit)) {
-        ++nfailures;
-        if(nfailures < max_failures) {
-          continue;
-        } else {
-          res = RES_BAD_ARG;
-          goto error;
-        }
-      }
-    /* Discard the hit if it is on a vertex/edge, and target a new position
-     * onto the current primitive */
+    /* Try another position onto the current primitive if there is no
+     * intersection or if it is on a vertex/edge */
     } while((SXD_HIT_NONE(&hit) || HIT_ON_BOUNDARY(&hit, P, dir))
          && ++istep < nsteps);
 
-    /* The hits of all targeted positions on the current primitive are on
-     * vertices. Challenge positions on another primitive. */
+    /* No valid intersection is found on the current primitive. Challenge
+     * another. */
     if(istep >= nsteps) continue;
 
     fX(normalize)(N, hit.normal);
@@ -1133,7 +1121,7 @@ XD(scene_get_medium)
     res = RES_BAD_OP;
     goto error;
   }
-  
+
 #if DIM == 2
   if(iprim > 10 && iprim > (size_t)((double)nprims * 0.05)) {
     log_warn(scn->dev,
@@ -1154,13 +1142,19 @@ exit:
   *out_medium = medium;
   return res;
 error:
+  {
+    /* RES_BAD_OP means that this is a recoverable issue. In such case, print a
+     * warning rather than an error. */
+    void (*log_func)(const struct sdis_device*, const char*, ...) =
+      (res == RES_BAD_OP ? log_warn : log_err);
 #if DIM == 2
-  log_err(scn->dev, "%s: could not retrieve the medium at {%g, %g}.\n",
-    FUNC_NAME, SPLIT2(pos));
+    log_func(scn->dev, "%s: could not retrieve the medium at {%g, %g}.\n",
+      FUNC_NAME, SPLIT2(pos));
 #else
-  log_err(scn->dev, "%s: could not retrieve the medium at {%g, %g, %g}.\n",
-    FUNC_NAME, SPLIT3(pos));
+    log_func(scn->dev, "%s: could not retrieve the medium at {%g, %g, %g}.\n",
+      FUNC_NAME, SPLIT3(pos));
 #endif
+  }
   goto exit;
 }
 
@@ -1230,13 +1224,6 @@ exit:
   *out_medium = medium;
   return res;
 error:
-#if DIM == 2
-  log_err(scn->dev, "%s: could not retrieve the medium at {%g, %g}.\n",
-    FUNC_NAME, SPLIT2(pos));
-#else
-  log_err(scn->dev, "%s: could not retrieve the medium at {%g, %g, %g}.\n",
-    FUNC_NAME, SPLIT3(pos));
-#endif
   goto exit;
 }