[osg-users] LineSegmentIntersector and MODEL Frame

[OpenSceneGraph Users]

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 <javascript:>> 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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