Hi Sergey,
>then create custom intersector to suite your needs see custom intersectors 
>Thanks for giving entry point, the chapter in Cookbook also suggest to do so, 
>I came to know that recently. 
One more little question, I created a XY grid (Z=0) which is composed of 
PrimitiveSet with GL_Lines, how can one implement the  snaping to the lines 
intersection points(intersection between line segments), IMHO thereis no need 
to create custom intersector to detect that and picking lines is unnecessary. 
As a result mouse may hoover anywhere in vast spatial space and may not detect 
the intersection point. How am I supposed to proceed with that  ?
Entry point will be appreciated.
Regards,

Date: Sun, 27 Jul 2014 00:59:01 +0400
From: sergey.fo...@gmail.com
To: osg-users@lists.openscenegraph.org
Subject: Re: [osg-users] Mouse World Position in Perspective View

Hi Sonya

>but what happens if mouse is close enough and supposed >to be snapped to 
>vertex but mouse is not on object.?


I can think of two things -  set bounding sphere to be larger so that you 
intersect object when you click near object ( see 
http://vtp.googlecode.com/svn-history/r7601/trunk/TerrainSDK/vtlib/vtosg/NodeOSG.cpp
  as an example), then create custom intersector to suite your needs see custom 
intersectors here 
http://www.packtpub.com/sites/default/files/downloads/6884_Chapter10.pdf 


Regards
Sergey



On Sat, Jul 26, 2014 at 11:11 PM, Sonya Blade <sonyablade2...@hotmail.com> 
wrote:




Hi Sergey, 
Thanks for the tutorial, but I believe that the problem is: Casted ray with 
world_mouse = screen_mouse*inverse(MVPW)
matrix manipulation is unware of whether it crossed an object or not, it simply 
returns near/far points of frustum.On the other hand using, the" 
LineSegmentIntersector >> getWorldIntersectionPoint()  " and example in OSG 
cookbook
Ch3 Selecting a point on the model solves the issue of what is behind the mouse 
but I believe that it has drawbacks. 
Because this tecnique requires the mouse to be hoovered on object, but what 
happens if mouse is close enough and supposed 
to be snapped to vertex but mouse is not on object.?

The above is my intuitive reasoning , I tried to put it in succinct manner and 
hope that I well versed it. If it is not clear  I'll try to 
ealaborate it with images.
Regards,
Date: Sat, 26 Jul 2014 14:11:38 +0400
From: sergey.fo...@gmail.com
To: osg-users@lists.openscenegraph.org

Subject: Re: [osg-users] Mouse World Position in Perspective View

Hi Sonya,

I think you could solve your problem if you understand theory what goes during 
the whole process and test if anything works from simplest examples, then after 
 tests  you'll uncover a problem



for theory I think following to links are useful, but see not only first link, 
but also second

http://www.mvps.org/directx/articles/rayproj.htm


http://www.mvps.org/directx/articles/improved_ray_picking.htm


Regards
Sergey



On Sat, Jul 26, 2014 at 1:53 AM, Sonya Blade <sonyablade2...@hotmail.com> wrote:





Dear All,
I'm having a hard time getting the correct results for the mouse position in 
world coordinates.The problem is: retrived world mouse position is not even 
close to those when I hoover over an 

object so I couldn't find any correlation between to which vertex of object is 
mouse close to. 
To obtain the world mouse position I use world_mouse = 
screen_mouse*inverse(MVPW), for obtaining 

the vertex position I use LineSegmentIntersector >> getWorldIntersectionPoint() 
and there is absolutey not any coherent value that I can find any relation. My 
aim was to snap the mouse to the closest vertex 

in object, but produced results are as follow. 
 world coords vertex(6.97538 20.55 18.7482" local coords vertex(0.876922 
-3.74963 4"Mouse Position -101.794 44.6545 -130.128"


Your help will be appreciated,                                    

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