star-3d

commit 4a2e1c1025a288048e63cca45400b596c0955b60
parent bd73e8281ea0c62700e1ccfd3f3a1cf229e72264
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Tue, 19 Jan 2021 15:10:02 +0100

Revert closest_point hit normal internals to float

To enable strict equality with geometrical normal

Diffstat:
M
src/s3d_scene_view_closest_point.c
 | 
21
++++++++++++---------

1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/src/s3d_scene_view_closest_point.c b/src/s3d_scene_view_closest_point.c
@@ -177,7 +177,7 @@ closest_point_mesh
   double query_pos_ws[3]; /* World space query position */
   double query_pos_ls[3]; /* Local space query position */
   double v0[3], v1[3], v2[3];
-  double E0[3], E1[3], Ng[3];
+  float E0[3], E1[3], Ng[3];
   double vec[3];
   double uv[2];
   float dst;
@@ -238,14 +238,17 @@ closest_point_mesh
 
   if(dst >= args->query->radius) return 0;
 
-  /* Compute the triangle normal in world space */
-  d3_sub(E0, v2, v0);
-  d3_sub(E1, v1, v0);
-  d3_cross(Ng, E0, E1);
+  /* Compute the triangle normal in world space (left hand convention). Keep
+   * it in float to avoid double-cast accuracy loss wrt user computed result */
+  f3_sub(E0, mesh_get_pos(geom->data.mesh) + ids[1] * 3,
+    mesh_get_pos(geom->data.mesh) + ids[0] * 3);
+  f3_sub(E1, mesh_get_pos(geom->data.mesh) + ids[2] * 3,
+    mesh_get_pos(geom->data.mesh) + ids[0] * 3);
+  f3_cross(Ng, E1, E0);
 
   /* Flip the geometric normal wrt the flip surface flag */
   flip_surface ^= geom->flip_surface;
-  if(flip_surface) d3_minus(Ng, Ng);
+  if(flip_surface) f3_minus(Ng, Ng);
 
   /* Setup the hit */
   hit.prim.shape__ = geom;
@@ -253,9 +256,9 @@ closest_point_mesh
   hit.distance = dst;
   hit.uv[0] = (float)uv[0];
   hit.uv[1] = (float)uv[1];
-  hit.normal[0] = (float)Ng[0];
-  hit.normal[1] = (float)Ng[1];
-  hit.normal[2] = (float)Ng[2];
+  hit.normal[0] = Ng[0];
+  hit.normal[1] = Ng[1];
+  hit.normal[2] = Ng[2];
   hit.prim.prim_id = args->primID;
   hit.prim.geom_id = geom->name;
   hit.prim.inst_id = inst ? inst->name : S3D_INVALID_ID;