Optimize bounding box bisection with more early culling

[libs/math.git] / source / geometry / shape.h

diff --git a/source/geometry/shape.h b/source/geometry/shape.h
index 8eb3157a17a19237779838e22efa46c97a67b142..920e4560454799d7828a50a9601e3ad4ba2295b7 100644 (file)
--- a/source/geometry/shape.h
+++ b/source/geometry/shape.h
@@ -14,6 +14,7 @@ namespace Geometry {
 enum Coverage
 {
        NO_COVERAGE,
+       UNCERTAIN_COVERAGE,
        PARTIAL_COVERAGE,
        FULL_COVERAGE
 };
@@ -96,6 +97,17 @@ inline BoundingBox<T, D> Shape<T, D>::bisect_axis_aligned_bounding_box(unsigned
 
                const LinAl::Vector<T, D> &min_pt = cell.bounding_box.get_minimum_point();
                const LinAl::Vector<T, D> &max_pt = cell.bounding_box.get_maximum_point();
+
+               // Skip cells that are already fully inside the established bounds.
+               bool internal = true;
+               for(unsigned i=0; (i<D && internal); ++i)
+                       internal = (min_pt[i]>=tight_min_pt[i] && max_pt[i]<=tight_max_pt[i]);
+               if(internal)
+               {
+                       queue.pop_front();
+                       continue;
+               }
+
                LinAl::Vector<T, D> center = (min_pt+max_pt)/T(2);
 
                // Bisect each dimension.
@@ -118,9 +130,8 @@ inline BoundingBox<T, D> Shape<T, D>::bisect_axis_aligned_bounding_box(unsigned
                        child.coverage = get_coverage(child.bounding_box);
                        if(child.coverage==FULL_COVERAGE || (child.level==detail && child.coverage!=NO_COVERAGE))
                        {
-                               /* Adjust the bounds when we are certain that it's covered by at
-                               least part of the shape.  Also adjust for uncertain results if
-                               we're on the last level. */
+                               /* Immediately merge cells with full coverage.  Also merge cells
+                               at the last level. */
                                for(unsigned j=0; j<D; ++j)
                                {
                                        tight_min_pt[j] = std::min(tight_min_pt[j], child_min_pt[j]);
@@ -128,6 +139,17 @@ inline BoundingBox<T, D> Shape<T, D>::bisect_axis_aligned_bounding_box(unsigned
                                }
                        }
                        else if(child.coverage==PARTIAL_COVERAGE)
+                       {
+                               /* Merge cells with confirmed partial coverage so the cell is
+                               left just outside the bounding box. */
+                               for(unsigned j=0; j<D; ++j)
+                               {
+                                       tight_min_pt[j] = std::min(tight_min_pt[j], child_max_pt[j]);
+                                       tight_max_pt[j] = std::max(tight_max_pt[j], child_min_pt[j]);
+                               }
+                       }
+
+                       if(child.level<detail && child.coverage!=NO_COVERAGE && child.coverage!=FULL_COVERAGE)
                                queue.push_back(child);
                }