Re: [osg-users] LineSegmentIntersector, IntersectionVisitor and children

[Robert Osfield]

Hi Julien-Charles,

The interesection code only using the node bounding spheres during
traversal, it doesn't use them for the final intersection calculation as
this is done against the actual primitives of the drawable leaves.   I can't
say way is wrong with your setup, but it won't be a parental bounding sphere
issue.

Robert.

On Tue, Sep 15, 2009 at 8:24 PM, Julien-Charles Levesque 
levesque...@gmail.com wrote:

 Hi,

 I am using LineSegmentIntersectors with IntersectionVisitor to do some ray
 casting in my architecture. Everything works fine to select and move
 objects. However I want to implement a drag-and-drop interaction, where I
 can move an object onto another and have something different happen. I want
 to obtain this object using the ray casting as well, so I cast a ray and
 check to get the first object in Intersections that is not my current object
 (which I saved in a member variable at the beginning of my drag-and-drop).

 It all works fine until I start interacting with parent/child objects. I
 have a sphere and a cube, the sphere is the parent of the cube. When I
 drag-and-drop my cube over black space, the IntersectionVisitor returns me
 the sphere (the parent) as the second object intersected even though there
 is nothing behind the cube at the place I dropped it.

 Now I believe this has something to do with the parent's bounding sphere
 including it's children and thus being counted as an intersection, but I'm
 not sure how I can deal with this kind of stuff. Then again, I could be
 mistaken.

 I tried reading about bounding spheres in the reference guide and did not
 see much, neither could I get much information (or enough information ;)
 about IntersectionVisitors.. any help would be strongly appreciated !


 Thanks in advance !

 Sincerely,
 Julien-Charles

 --
 Read this topic online here:
 http://forum.openscenegraph.org/viewtopic.php?p=17395#17395





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[osg-users] LineSegmentIntersector, IntersectionVisitor and children

[Julien-Charles Levesque]

Hi,

I am using LineSegmentIntersectors with IntersectionVisitor to do some ray 
casting in my architecture. Everything works fine to select and move objects. 
However I want to implement a drag-and-drop interaction, where I can move an 
object onto another and have something different happen. I want to obtain this 
object using the ray casting as well, so I cast a ray and check to get the 
first object in Intersections that is not my current object (which I saved in a 
member variable at the beginning of my drag-and-drop). 

It all works fine until I start interacting with parent/child objects. I have a 
sphere and a cube, the sphere is the parent of the cube. When I drag-and-drop 
my cube over black space, the IntersectionVisitor returns me the sphere (the 
parent) as the second object intersected even though there is nothing behind 
the cube at the place I dropped it. 

Now I believe this has something to do with the parent's bounding sphere 
including it's children and thus being counted as an intersection, but I'm not 
sure how I can deal with this kind of stuff. Then again, I could be mistaken.

I tried reading about bounding spheres in the reference guide and did not see 
much, neither could I get much information (or enough information ;) about 
IntersectionVisitors.. any help would be strongly appreciated !


Thanks in advance !

Sincerely,
Julien-Charles

--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=17395#17395





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