Improve getPointedThing() (#4346)

* Improved getPointedThing()

The new algorithm checks every node exactly once.
Now the point and normal vector of the collision is also returned in the
PointedThing (currently they are not used outside of the function).
Now the CNodeDefManager keeps the union of all possible nodeboxes, so
the raycast won't miss any nodes. Also if there are only small
nodeboxes, getPointedThing() is exceptionally fast.
Also adds unit test for VoxelLineIterator.

* Cleanup, code move

This commit moves getPointedThing() and
Client::getSelectedActiveObject() to ClientEnvironment.
The map nodes now can decide which neighbors they are connecting to
(MapNode::getNeighbors()).

1 files changed, 46 insertions, 0 deletions

diff --git a/src/mapnode.cpp b/src/mapnode.cpp
index 5efebf3d8..f1a7f3e61 100644
--- a/src/mapnode.cpp
+++ b/src/mapnode.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mapnode.h"
 #include "porting.h"
 #include "nodedef.h"
+#include "map.h"
 #include "content_mapnode.h" // For mapnode_translate_*_internal
 #include "serialization.h" // For ser_ver_supported
 #include "util/serialize.h"
@@ -453,6 +454,51 @@ void transformNodeBox(const MapNode &n, const NodeBox &nodebox,
 	}
 }
 
+static inline void getNeighborConnectingFace(
+	v3s16 p, INodeDefManager *nodedef,
+	Map *map, MapNode n, u8 bitmask, u8 *neighbors)
+{
+	MapNode n2 = map->getNodeNoEx(p);
+	if (nodedef->nodeboxConnects(n, n2, bitmask))
+		*neighbors |= bitmask;
+}
+
+u8 MapNode::getNeighbors(v3s16 p, Map *map)
+{
+	INodeDefManager *nodedef=map->getNodeDefManager();
+	u8 neighbors = 0;
+	const ContentFeatures &f = nodedef->get(*this);
+	// locate possible neighboring nodes to connect to
+	if (f.drawtype == NDT_NODEBOX && f.node_box.type == NODEBOX_CONNECTED) {
+		v3s16 p2 = p;
+
+		p2.Y++;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 1, &neighbors);
+
+		p2 = p;
+		p2.Y--;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 2, &neighbors);
+
+		p2 = p;
+		p2.Z--;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 4, &neighbors);
+
+		p2 = p;
+		p2.X--;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 8, &neighbors);
+
+		p2 = p;
+		p2.Z++;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 16, &neighbors);
+
+		p2 = p;
+		p2.X++;
+		getNeighborConnectingFace(p2, nodedef, map, *this, 32, &neighbors);
+	}
+
+	return neighbors;
+}
+
 void MapNode::getNodeBoxes(INodeDefManager *nodemgr, std::vector<aabb3f> *boxes, u8 neighbors)
 {
 	const ContentFeatures &f = nodemgr->get(*this);