Merge pull request #903 from Geode-solutions/fix/big-partial-triangle

fix(AABB): add compute triangle vs element bboxes intersection

Author: panquez

include/geode/geometry/aabb.h

@@ -34,6 +34,7 @@
 #include <geode/basic/pimpl.h>
 
 #include <geode/geometry/basic_objects/infinite_line.h>
+#include <geode/geometry/basic_objects/triangle.h>
 #include <geode/geometry/bounding_box.h>
 #include <geode/geometry/common.h>
 
@@ -216,6 +217,25 @@ namespace geode
             const Segment< dimension >& segment,
             EvalIntersection& action ) const;
 
+        /*!
+         * @brief Computes the intersections between a given Triangle and
+         * all element boxes.
+         * @param[in] triangle The triangle to test.
+         * @param[in] action The functor to run when a box is intersected by the
+         * segment.
+         * @tparam EvalIntersection this functor should have an operator()
+         * defined like this:
+         * bool operator()( index_t cur_element_box ) ;
+         * @note the operator define what to do with the box \p cur_element_box
+         * if it is intersected by the \p triangle.
+         * @note The returned boolean indicates if the search should stop or
+         * continue. Return true to stop the search, false to continue.
+         */
+        template < class EvalIntersection >
+        void compute_triangle_element_bbox_intersections(
+            const Triangle< dimension >& triangle,
+            EvalIntersection& action ) const;
+
     private:
         IMPLEMENTATION_MEMBER( impl_ );
     };

include/geode/geometry/detail/aabb_impl.h

@@ -101,6 +101,14 @@ namespace geode
             index_t element_end,
             ACTION& action ) const;
 
+        template < typename ACTION >
+        bool triangle_intersect_recursive(
+            const Triangle< dimension >& triangle,
+            index_t node_index,
+            index_t element_begin,
+            index_t element_end,
+            ACTION& action ) const;
+
         template < typename ACTION >
         bool self_intersect_recursive( index_t node_index1,
             index_t element_begin1,
@@ -228,6 +236,19 @@ namespace geode
             line, Impl::ROOT_INDEX, 0, nb_bboxes(), action );
     }
 
+    template < index_t dimension >
+    template < class EvalIntersection >
+    void AABBTree< dimension >::compute_triangle_element_bbox_intersections(
+        const Triangle< dimension >& triangle, EvalIntersection& action ) const
+    {
+        if( nb_bboxes() == 0 )
+        {
+            return;
+        }
+        impl_->triangle_intersect_recursive(
+            triangle, Impl::ROOT_INDEX, 0, nb_bboxes(), action );
+    }
+
     template < index_t dimension >
     template < class EvalIntersection >
     void AABBTree< dimension >::compute_segment_element_bbox_intersections(
@@ -350,6 +371,41 @@ namespace geode
             box, it.child_right, it.middle_box, element_end, action );
     }
 
+    template < index_t dimension >
+    template < typename ACTION >
+    bool AABBTree< dimension >::Impl::triangle_intersect_recursive(
+        const Triangle< dimension >& triangle,
+        index_t node_index,
+        index_t element_begin,
+        index_t element_end,
+        ACTION& action ) const
+    {
+        OPENGEODE_ASSERT( node_index < tree_.size(), "Node out of tree range" );
+        OPENGEODE_ASSERT(
+            element_begin != element_end, "No iteration allowed start == end" );
+
+        // Prune sub-tree that does not have intersection
+        if( !node( node_index ).intersects( triangle ) )
+        {
+            return false;
+        }
+
+        if( is_leaf( element_begin, element_end ) )
+        {
+            return action( mapping_morton( element_begin ) );
+        }
+
+        const auto it =
+            get_recursive_iterators( node_index, element_begin, element_end );
+        if( triangle_intersect_recursive( triangle, it.child_left,
+                element_begin, it.middle_box, action ) )
+        {
+            return true;
+        }
+        return triangle_intersect_recursive(
+            triangle, it.child_right, it.middle_box, element_end, action );
+    }
+
     template < index_t dimension >
     template < typename ACTION >
     bool AABBTree< dimension >::Impl::self_intersect_recursive(