Hi,

Will this make drive manipulator less jumpy in large (WGS84 ellipsoid) 
databases ? That would be cool ;-)

Wojtek

----- Original Message ----- 
From: "Robert Osfield" <[EMAIL PROTECTED]>
To: "OpenSceneGraph Submissions" <[email protected]>
Sent: Monday, February 18, 2008 2:13 PM
Subject: Re: [osg-submissions] try doubles for math 
inLineSegment::intersect() methods


> Hi Andy,
>
> I'm tempted to just convert LineSegment to use Vec3d, this would
> ensure that all transformation done of LineSegments would retain good
> accuracy, often we do world to local intersection tests where the
> world is a whole earth model.  Changing to doubles in the Vec3
> elements should tackle the intersection issues as well.
>
> Thoughts?
>
> Robert.
>
> On Feb 6, 2008 9:50 PM, Andy Skinner <[EMAIL PROTECTED]> wrote:
>> This is to address what I've been asking about on the users list.  We've
>> got cases where the float math just isn't enough to do the intersections
>> properly.  I had to convert everything to doubles for it to work.
>>
>> One optimization is that Vec3d versions of _s, _e, and _s-_e could be
>> stored in the LineSegment and calculated when needed in an intersection.
>> The intersect() method is const, so I didn't do it here.
>>
>> I am a little less sure of the intersect method that takes 3 Vec3s and a
>> float reference.  I saw it did a-b one place and b-a another, and I used
>> a Vec3d for this and used its operator- for the second occurrence.  I'm
>> not sure how much of this is worth it.
>>
>> If those who do a lot of these intersections could time this and tell me
>> how it does, I'd appreciate it.
>>
>> andy
>>
>>
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>>
>>
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