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()).

src/unittest/test_voxelalgorithms.cpp

@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "gamedef.h"
 #include "voxelalgorithms.h"
+#include "util/numeric.h"
 
 class TestVoxelAlgorithms : public TestBase {
 public:
@@ -31,6 +32,7 @@ public:
 
 	void testPropogateSunlight(INodeDefManager *ndef);
 	void testClearLightAndCollectSources(INodeDefManager *ndef);
+	void testVoxelLineIterator(INodeDefManager *ndef);
 };
 
 static TestVoxelAlgorithms g_test_instance;
@@ -41,6 +43,7 @@ void TestVoxelAlgorithms::runTests(IGameDef *gamedef)
 
 	TEST(testPropogateSunlight, ndef);
 	TEST(testClearLightAndCollectSources, ndef);
+	TEST(testVoxelLineIterator, ndef);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -202,3 +205,59 @@ void TestVoxelAlgorithms::testClearLightAndCollectSources(INodeDefManager *ndef)
 		UASSERT(unlight_from.size() == 1);
 	}
 }
+
+void TestVoxelAlgorithms::testVoxelLineIterator(INodeDefManager *ndef)
+{
+	// Test some lines
+	// Do not test lines that start or end on the border of
+	// two voxels as rounding errors can make the test fail!
+	std::vector<core::line3d<f32> > lines;
+	for (f32 x = -9.1; x < 9; x += 3.124) {
+	for (f32 y = -9.2; y < 9; y += 3.123) {
+	for (f32 z = -9.3; z < 9; z += 3.122) {
+		lines.push_back(core::line3d<f32>(-x, -y, -z, x, y, z));
+	}
+	}
+	}
+	lines.push_back(core::line3d<f32>(0, 0, 0, 0, 0, 0));
+	// Test every line
+	std::vector<core::line3d<f32> >::iterator it = lines.begin();
+	for (; it < lines.end(); it++) {
+		core::line3d<f32> l = *it;
+
+		// Initialize test
+		voxalgo::VoxelLineIterator iterator(l.start, l.getVector());
+
+		//Test the first voxel
+		v3s16 start_voxel = floatToInt(l.start, 1);
+		UASSERT(iterator.m_current_node_pos == start_voxel);
+
+		// Values for testing
+		v3s16 end_voxel = floatToInt(l.end, 1);
+		v3s16 voxel_vector = end_voxel - start_voxel;
+		int nodecount = abs(voxel_vector.X) + abs(voxel_vector.Y)
+			+ abs(voxel_vector.Z);
+		int actual_nodecount = 0;
+		v3s16 old_voxel = iterator.m_current_node_pos;
+
+		while (iterator.hasNext()) {
+			iterator.next();
+			actual_nodecount++;
+			v3s16 new_voxel = iterator.m_current_node_pos;
+			// This must be a neighbor of the old voxel
+			UASSERTEQ(f32, (new_voxel - old_voxel).getLengthSQ(), 1);
+			// The line must intersect with the voxel
+			v3f voxel_center = intToFloat(iterator.m_current_node_pos, 1);
+			aabb3f box(voxel_center - v3f(0.5, 0.5, 0.5),
+				voxel_center + v3f(0.5, 0.5, 0.5));
+			UASSERT(box.intersectsWithLine(l));
+			// Update old voxel
+			old_voxel = new_voxel;
+		}
+
+		// Test last node
+		UASSERT(iterator.m_current_node_pos == end_voxel);
+		// Test node count
+		UASSERTEQ(int, actual_nodecount, nodecount);
+	}
+}