ogre helpers point_cloud: add size into bounds

Add the size of the point visual into the bounding box.
For small or zero sized points this makes little difference,
but for large points (such as visualizing an octomap with
large compressed regions), it is important to add the bounds
to keep the points visible at the very edges of the cloud.

src/rviz/ogre_helpers/point_cloud.cpp

@@ -480,6 +480,7 @@ void PointCloud::addPoints(Point* points, uint32_t num_points)
 
   Ogre::AxisAlignedBox aabb;
   aabb.setNull();
+  Ogre::Vector3 point_size_offset(width_/2.0, height_/2.0, depth_/2.0);
   uint32_t current_vertex_count = 0;
   bounding_radius_ = 0.0f;
   uint32_t vertex_size = 0;
@@ -539,7 +540,8 @@ void PointCloud::addPoints(Point* points, uint32_t num_points)
       root->convertColourValue(p.color, &color);
     }
 
-    aabb.merge(p.position);
+    aabb.merge(p.position + point_size_offset);
+    aabb.merge(p.position - point_size_offset);
 
     float x = p.position.x;
     float y = p.position.y;