stardis-solver

commit 5ae79b240a404177cee76e139841bceec8cadb42
parent 402f34f44e40fd351ae14469f8834084d3b749b0
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Mon, 28 May 2018 10:45:28 +0200

Fix inaccuracies in the scene_get_medium_3d function

Diffstat:
M
src/sdis_scene.c
 | 
76
+++++++++++++++++++++++++++++++++++++++++++++-------------------------------

1 file changed, 45 insertions(+), 31 deletions(-)
diff --git a/src/sdis_scene.c b/src/sdis_scene.c
@@ -459,9 +459,17 @@ scene_get_medium_2d
   size_t iprim, nprims;
   size_t nfailures = 0;
   const size_t max_failures = 10;
+  /* Range of the parametric coordinate into which positions are challenged */
+  const float s_range[2] = {0.25, 0.75};
+  const size_t s_nsteps = 3; /* #challenges per primitive into the range */
+  float s;
+  float s_step;
   res_T res = RES_OK;
   ASSERT(scn && pos);
 
+  s_step = (s_range[1] - s_range[0]) / (float)(s_nsteps-1);
+  s = s_range[0];
+
   S2D(scene_view_primitives_count(scn->s2d_view, &nprims));
   FOR_EACH(iprim, 0, nprims) {
     struct s2d_hit hit;
@@ -470,14 +478,6 @@ scene_get_medium_2d
     const float range[2] = {0.f, FLT_MAX};
     float N[2], P[2], dir[2], cos_N_dir;
 
-    /* Range of the parametric coordinate into which positions are challenged */
-    const float s_range[2] = {0.25, 0.75};
-    const size_t s_nsteps = 3; /* #challenges per primitive into the range */
-    float s;
-    float s_step;
-
-    s_step = (s_range[1] - s_range[0]) / (float)(s_nsteps-1);
-    s = s_range[0];
     do {
       /* Retrieve a position onto the primitive */
       S2D(scene_view_get_primitive(scn->s2d_view, (unsigned)iprim, &prim));
@@ -502,9 +502,9 @@ scene_get_medium_2d
      * target a new position onto the current primitive */
     } while(hit_on_vertex(&hit) && (s+=s_step) <= s_range[1]);
 
-    /* The hits of all targeted positions on the current primitive, are on
-     * edges. Try positions on another primitive. */
-    if(s > 0.75f) continue;
+    /* The hits of all targeted positions on the current primitive are on
+     * vertices. Challenge positions on another primitive. */
+    if(s > s_range[1]) continue;
 
     f2_normalize(N, hit.normal);
     cos_N_dir = f2_dot(N, dir);
@@ -546,42 +546,56 @@ scene_get_medium_3d
   size_t iprim, nprims;
   size_t nfailures = 0;
   const size_t max_failures = 10;
+  float st[3][2]; /* Position to challenge onto the primitive */
+  const size_t nsteps = sizeof(st)/sizeof(float[2]);
   res_T res = RES_OK;
   ASSERT(scn && pos);
 
+  /* Setup the position to challenge onto the primitives */
+  f2(st[0], 1.f/6.f, 5.f/12.f);
+  f2(st[1], 5.f/12.f, 1.f/6.f);
+  f2(st[2], 5.f/12.f, 5.f/12.f);
+
   S3D(scene_view_primitives_count(scn->s3d_view, &nprims));
   FOR_EACH(iprim, 0, nprims) {
     struct s3d_hit hit;
     struct s3d_attrib attr;
     struct s3d_primitive prim;
-    float st[2];
     const float range[2] = {0.f, FLT_MAX};
     float N[3], P[3], dir[3], cos_N_dir;
-    st[0] = st[1] = 1.f / 3.f; /* Or MSVC will issue a warning */
+    size_t istep = 0;
 
-    /* Retrieve a position onto the primitive */
-    S3D(scene_view_get_primitive(scn->s3d_view, (unsigned)iprim, &prim));
-    S3D(primitive_get_attrib(&prim, S3D_POSITION, st, &attr));
+    do {
+      /* Retrieve a position onto the primitive */
+      S3D(scene_view_get_primitive(scn->s3d_view, (unsigned)iprim, &prim));
+      S3D(primitive_get_attrib(&prim, S3D_POSITION, st[istep], &attr));
 
-    /* Trace a ray from the randomw walk vertex  toward the retrieved primitive
-     * position */
-    f3_normalize(dir, f3_sub(dir, attr.value, f3_set_d3(P, pos)));
-    S3D(scene_view_trace_ray(scn->s3d_view, P, dir, range, NULL, &hit));
+      /* Trace a ray from the randomw walk vertex  toward the retrieved primitive
+       * position */
+      f3_normalize(dir, f3_sub(dir, attr.value, f3_set_d3(P, pos)));
+      S3D(scene_view_trace_ray(scn->s3d_view, P, dir, range, NULL, &hit));
+
+      /* Unforeseen error. One has to intersect a primitive ! */
+      if(S3D_HIT_NONE(&hit)) {
+        ++nfailures;
+        if(nfailures < max_failures) {
+          continue;
+        } else {
+          res = RES_BAD_ARG;
+          goto error;
+        }
+      }
+    /* Discard the hit if it is on an edge, i.e. between 2 triangles,  and
+     * target a new position onto the current primitive */
+    } while(hit_on_edge(&hit) && ++istep < nsteps);
+
+    /* The hits of all targeted positions on the current primitive are on
+     * edges. Challenge positions on another primitive. */
+    if(istep >= nsteps) continue;
 
     f3_normalize(N, hit.normal);
     cos_N_dir = f3_dot(N, dir);
 
-    /* Unforeseen error. One has to intersect a primitive ! */
-    if(S3D_HIT_NONE(&hit)) {
-      ++nfailures;
-      if(nfailures < max_failures) {
-        continue;
-      } else {
-        res = RES_BAD_ARG;
-        goto error;
-      }
-    }
-
     if(absf(cos_N_dir) > 1.e-1f) { /* Not roughly orthognonal */
       const struct sdis_interface* interf;
       interf = scene_get_interface(scn, hit.prim.prim_id);