star-uvm

commit 72cb802c1c7fa44839f666feeed8ee1fcf4c8ea4
parent da4b64dc969778124ad10baf3b08b060f0038032
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Tue, 15 Dec 2020 14:37:53 +0100

Fix tetrahedron/aabb intersection test

Update the profile of the suvm_polyhedron_intersect_aabb function: return
the intersection type, i.e. [is_]included, partial or none.

Diffstat:
M
src/suvm.h
 | 
9
++++++++-
M
src/suvm_primitive.c
 | 
35
++++++++++++++++++++++-------------

2 files changed, 30 insertions(+), 14 deletions(-)
diff --git a/src/suvm.h b/src/suvm.h
@@ -114,6 +114,13 @@ struct suvm_tetrahedral_mesh_args {
 static const struct suvm_tetrahedral_mesh_args SUVM_TETRAHEDRAL_MESH_ARGS_NULL =
   SUVM_TETRAHEDRAL_MESH_ARGS_NULL__;
 
+enum suvm_intersection_type {
+  SUVM_INTERSECT_NONE,
+  SUVM_INTERSECT_INCLUDE,
+  SUVM_INTERSECT_IS_INCLUDED,
+  SUVM_INTERSECT_PARTIAL
+};
+
 /* Callback invoked on suvm_volume_intersect_aabb invocation on each primitives
  * intersected by the submitted Axis Aligned Bounding Box */
 typedef void
@@ -215,7 +222,7 @@ suvm_primitive_setup_polyhedron
   (const struct suvm_primitive* prim,
    struct suvm_polyhedron* poly);
 
-SUVM_API int
+SUVM_API enum suvm_intersection_type
 suvm_polyhedron_intersect_aabb
   (const struct suvm_polyhedron* poly,
    const float low[3],
diff --git a/src/suvm_primitive.c b/src/suvm_primitive.c
@@ -36,7 +36,7 @@ suvm_primitive_setup_polyhedron
  * Its implementation follows the algorithms proposed by N. Greene in
  * "Detecting intersection of a rectangular solid and a convex polyhedron"
  * (Graphics Gems IV, 1994, p74--82) */
-int
+enum suvm_intersection_type
 suvm_polyhedron_intersect_aabb
   (const struct suvm_polyhedron* tetra,
    const float low[3],
@@ -45,10 +45,10 @@ suvm_polyhedron_intersect_aabb
   enum { X, Y, Z, AXES_COUNT }; /* Syntactic sugar */
   float intersect_aabb_low[AXES_COUNT];
   float intersect_aabb_upp[AXES_COUNT];
-  int i;
   int nplanes_including_aabb;
+  int i;
 
-  ASSERT(tetra && low && !upp);
+  ASSERT(tetra && low && upp);
   ASSERT(low[0] < upp[0]);
   ASSERT(low[1] < upp[1]);
   ASSERT(low[2] < upp[2]);
@@ -58,14 +58,17 @@ suvm_polyhedron_intersect_aabb
     intersect_aabb_low[i] = MMAX(low[i], tetra->lower[i]);
     intersect_aabb_upp[i] = MMIN(upp[i], tetra->upper[i]);
     if(intersect_aabb_low[i] > intersect_aabb_upp[i]) /* Do not intersect */
-      return 0;
+      return SUVM_INTERSECT_NONE;
   }
 
   /* Check if the tetrahedron is included into the aabb */
-  if(intersect_aabb_low[X] == low[X]
-  && intersect_aabb_low[Y] == low[Y]
-  && intersect_aabb_low[Z] == low[Z]) {
-    return 1;
+  if(intersect_aabb_low[X] == tetra->lower[X]
+  && intersect_aabb_low[Y] == tetra->lower[Y]
+  && intersect_aabb_low[Z] == tetra->lower[Z]
+  && intersect_aabb_upp[X] == tetra->upper[X]
+  && intersect_aabb_upp[Y] == tetra->upper[Y]
+  && intersect_aabb_upp[Z] == tetra->upper[Z]) {
+    return SUVM_INTERSECT_IS_INCLUDED;
   }
 
   /* #planes that totally includes the aabb on its positive side */
@@ -87,19 +90,23 @@ suvm_polyhedron_intersect_aabb
      * 'p', aka the farthest aabb vertex in the positive direction of the plane
      * normal, is not in the positive half space. In this case, the aabb is
      * entirely outside the tetrahedron */
-    if((f3_dot(tetra->N[i], p) + tetra->D[i]) < 0) return 0;
+    if((f3_dot(tetra->N[i], p) + tetra->D[i]) < 0) {
+      return SUVM_INTERSECT_NONE;
+    }
 
     /* Check if the box is totally inside the given plane. To do this, check
      * that 'n', aka the farthest aabb vertex in the negative direction of the
      * plane normal, is inside the positive half space */
-    if((f3_dot(tetra->N[i], n) + tetra->D[i]) > 0) {
+    if((f3_dot(tetra->N[i], n) + tetra->D[i]) >= 0) {
       /* Register this plane as a plane including the aabb */
       nplanes_including_aabb += 1;
     }
   }
 
   /* Check if the aabb is entirely included into the tetrahedron */
-  if(nplanes_including_aabb == 4) return 1;
+  if(nplanes_including_aabb == 4) {
+    return SUVM_INTERSECT_INCLUDE;
+  }
 
   /* For each silhouette edge in each projection plane, check if it totally
    * exclude the projected aabb */
@@ -123,12 +130,14 @@ suvm_polyhedron_intersect_aabb
       /* Check that the projected aabb along the 'i'th axis is totally outside
        * the current silhouette edge. That means that the aabb is entirely
        * outside the tetrahedron and thus that they do not intersect */
-      if((f2_dot(tetra->Ep[i][iedge], p) + tetra->Ep[i][iedge][2]) < 0) return 0;
+      if((f2_dot(tetra->Ep[i][iedge], p) + tetra->Ep[i][iedge][2]) < 0) {
+        return SUVM_INTERSECT_NONE;
+      }
     }
   }
 
   /* The tetrahedron and the aabb are partially intersecting */
-  return 1;
+  return SUVM_INTERSECT_PARTIAL;
 }