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| Re: 3d device coordinates from a 3D polyline.... [message #81502 is a reply to message #81501] |
Mon, 01 October 2012 10:07   |
George.millward
Messages: 26
Registered: October 2012
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Junior Member |
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On Monday, October 1, 2012 6:32:00 AM UTC-6, David Fanning wrote:
> George.millward@yahoo.com writes:
>
>
>
>> I have am idlgrpolyline which I can rotate in a 3D view (with the trackball).
>
>> I want to know the 2D coordinates of this line in the device (ie,the 2D the projection in the window). Can't figure it out.
>
>
>
> I'm no expert in this area, but I think the 3D to 2D
>
> conversions of the transformation matrix (which you
>
> can recover from the trackball) are well known. You
>
> can read the answer at the bottom of this article,
>
> for example:
>
>
>
> http://math.stackexchange.com/questions/336/why-are-3d-
>
> transformation-matrices-4x4-instead-of-3x3
>
>
>
> Cheers,
>
>
>
> David
>
>
>
>
>
> --
>
> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
Hmm,
So there is nothing in the object graphics system like the 'CONVERT_COORD' routine ?
George.
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| Re: 3d device coordinates from a 3D polyline.... [message #81597 is a reply to message #81502] |
Tue, 02 October 2012 02:22 |
lecacheux.alain
Messages: 325
Registered: January 2008
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Senior Member |
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Le lundi 1 octobre 2012 19:07:22 UTC+2, (inconnu) a écrit :
> On Monday, October 1, 2012 6:32:00 AM UTC-6, David Fanning wrote:
>
>>> I have am idlgrpolyline which I can rotate in a 3D view (with the trackball).
>
>>
>
>>> I want to know the 2D coordinates of this line in the device (ie,the 2D the projection in the window). Can't figure it out.
>
>>
>
>>
>
>>
>
>> I'm no expert in this area, but I think the 3D to 2D
>
>>
>
>> conversions of the transformation matrix (which you
>
>>
>
>> can recover from the trackball) are well known. You
>
>>
>
>> can read the answer at the bottom of this article,
>
>>
>
>> for example:
>
>>
>
>>
>
>>
>
>> http://math.stackexchange.com/questions/336/why-are-3d-
>
>>
>
>> transformation-matrices-4x4-instead-of-3x3
>
>>
>
>>
>
>>
>
>> Cheers,
>
>>
>
>>
>
>>
>
>> David
>
>>
>
>>
>
>>
>
>>
>
>>
>
>> --
>
>>
>
>> David Fanning, Ph.D.
>
>>
>
>> Fanning Software Consulting, Inc.
>
>>
>
>> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
>>
>
>> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
>
>
>
>
>
> Hmm,
>
>
>
> So there is nothing in the object graphics system like the 'CONVERT_COORD' routine ?
>
>
>
> George.
In Object Graphics and New Graphics you can use "[XYZ]COORD_CONV" and
"ConvertCoord" methods, respectively. The last one being quite similar to the "Convert_Coord" function in Direct Graphics.
Alain.
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