htrdr

commit 770463352b8229482fd4768274babd449d95f8be
parent ee2302d0ec7b350dda4f9280f2d68d4167aed35f
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu, 10 Nov 2022 15:37:17 +0100

htrdr-planeto: upd the calculation of the direct contribution

Previously, extinction transmissivity was calculated assuming an
infinite distance between the source and the position to be considered.

This commit adds the htrdr_planeto_source_distance_to function that
calculates the distance between the surface of the source and a given
position. The extinction transmissivity now uses this distance.

Diffstat:
M
src/planeto/htrdr_planeto_compute_radiance.c
 | 
9
+++++++--
M
src/planeto/htrdr_planeto_source.c
 | 
14
++++++++++++++
M
src/planeto/htrdr_planeto_source.h
 | 
7
+++++++

3 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/src/planeto/htrdr_planeto_compute_radiance.c b/src/planeto/htrdr_planeto_compute_radiance.c
@@ -262,6 +262,7 @@ direct_contribution
   struct s3d_hit hit;
   double Tr;
   double Ld;
+  double src_dst;
   ASSERT(cmd && args && pos && dir);
 
   /* Is the source hidden? */
@@ -271,7 +272,11 @@ direct_contribution
   RNGRD(trace_ray(cmd->ground, &rt, &hit));
   if(!S3D_HIT_NONE(&hit)) return 0;
 
-  Tr = transmissivity(cmd, args, RNATM_RADCOEF_Kext, pos, dir, INF);
+  /* Calculate the distance between the source and `pos' */
+  src_dst = htrdr_planeto_source_distance_to(cmd->source, pos);
+  ASSERT(src_dst >= 0);
+
+  Tr = transmissivity(cmd, args, RNATM_RADCOEF_Kext, pos, dir, src_dst);
   Ld = htrdr_planeto_source_get_radiance(cmd->source, args->wlen);
   return Ld * Tr;
 }
@@ -498,7 +503,7 @@ planeto_compute_radiance
   double dir[3];
   double L = 0; /* Radiance in W/m²/sr/m */
   double Tr_abs = 1; /* Absorption transmissivity */
-  size_t nsc = 0; /* For debug */
+  size_t nsc = 0; /* Number of scatterings (for debug) */
   ASSERT(cmd && check_planeto_compute_radiance_args(cmd, args) == RES_OK);
 
   d3_set(pos, args->path_org);
diff --git a/src/planeto/htrdr_planeto_source.c b/src/planeto/htrdr_planeto_source.c
@@ -152,6 +152,20 @@ htrdr_planeto_source_get_radiance
     (wlen*1e-9/*From nm to m*/, source->temperature);
 }
 
+double
+htrdr_planeto_source_distance_to
+  (const struct htrdr_planeto_source* source,
+   const double pos[3])
+{
+  double vec[3];
+  double dst;
+  ASSERT(source && pos);
+
+  d3_sub(vec, source->position, pos);
+  dst = d3_len(vec);
+  return dst - source->radius;
+}
+
 int
 htrdr_planeto_source_is_targeted
   (const struct htrdr_planeto_source* source,
diff --git a/src/planeto/htrdr_planeto_source.h b/src/planeto/htrdr_planeto_source.h
@@ -53,6 +53,13 @@ htrdr_planeto_source_get_radiance
   (const struct htrdr_planeto_source* source,
    const double wlen); /* In nanometers */
 
+/* Return the distance between the source surface and the input position. Can
+ * be negative if the position is in the source */
+extern LOCAL_SYM double /* In m */
+htrdr_planeto_source_distance_to
+  (const struct htrdr_planeto_source* source,
+   const double pos[3]);
+
 /* Return 1 if the source is targeted by the submitted ray and 0 otherwise */
 extern LOCAL_SYM int
 htrdr_planeto_source_is_targeted