[osg-users] LineSegmentIntersector and MODEL Frame

[OpenSceneGraph Users]

I found the problem, and it was mine. It helps if I attach my root node to 
the scene BEFORE I try to insect with it. ;)

On Monday, February 3, 2020 at 1:04:10 PM UTC-5, Nonsanity wrote:
>
> Thanks. I had thought to apply the visitor to the scene, but GetScene() 
> didn't have Accept(). With your confirmation that using the scene was 
> correct, I found that viewer.getSceneData()->accept( iv ) did exist.
>
> However, calling that line just results in a segfault. The rest of the 
> code is the same as before. I'm going to search to see if I'm doing 
> something obviously wrong, but in case I got the above line incorrect, I 
> wanted to post my failed results here for further comment.
>
>
> On Monday, February 3, 2020 at 3:06:33 AM UTC-5, OpenSceneGraph Users 
> wrote:
>>
>> Hi Chris,
>> I guess you want the scene to accept the IntersectionVisitor, not the 
>> camera.
>> Laurens.
>>
>> On Sat, Feb 1, 2020 at 1:18 PM OpenSceneGraph Users <
>> osg-... at lists.openscenegraph.org> wrote:
>>
>>> I have a scene built with a few objects loaded, the most pertinent one 
>>> being a large plane surface centered at the origin. I want to cast a ray 
>>> from a particular point at a particular angle inside the scene and get a 
>>> list of everything it intersects—both the point of intersection and the 
>>> Node object. Most examples of using intersectors involve picking from the 
>>> window, so I haven't seen exactly what I wanted. But from what I've read, 
>>> the following should at least be close:
>>>
>>>     Vec3d start( 0.0, 0.0, 100.0 );
>>>     Vec3d end( 0.0, 0.0, -100.0 );
>>>     ref_ptr<LineSegmentIntersector> intsec = new LineSegmentIntersector( 
>>> Intersector::MODEL, start, end );
>>>     IntersectionVisitor iv( intsec.get() );
>>>     viewer.getCamera()->accept( iv );
>>>     cout << intsec->containsIntersections() << endl;
>>>
>>> My start and end points in this snippet are well above and well below 
>>> the surface object. So that plane object should definitely be intersected 
>>> by a line running between them. However the containsIntersections function 
>>> always returns false.
>>>
>>> Immediately after making this preliminary test pick, the program calls 
>>> viewer.run() so I know everything is arranged as expected in the scene. So 
>>> my guess is that I'm missunderstanding how the visitor works. Perhaps the 
>>> accept() function is not what I should be using to execute the intersector?
>>>
>>>  ~ Chris
>>>
>>>
>>>
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