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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

Senior Member

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:
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>>> I have am idlgrpolyline which I can rotate in a 3D view (with the trackball).
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>>> 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.
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>> I'm no expert in this area, but I think the 3D to 2D
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>> conversions of the transformation matrix (which you
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>> can recover from the trackball) are well known. You
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>> can read the answer at the bottom of this article,
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>> for example:
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>> http://math.stackexchange.com/questions/336/why-are-3d-
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>> transformation-matrices-4x4-instead-of-3x3
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>> Cheers,
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>> David
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>> --
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>> David Fanning, Ph.D.
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>> Fanning Software Consulting, Inc.
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>> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
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>> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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> Hmm,
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> So there is nothing in the object graphics system like the 'CONVERT_COORD' routine ?
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> 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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[Message index]

		Re: 3d device coordinates from a 3D polyline.... By: DavidF[1] on Mon, 01 October 2012 10:10
		Re: 3d device coordinates from a 3D polyline.... By: George.millward on Mon, 01 October 2012 10:07
		Re: 3d device coordinates from a 3D polyline.... By: David Fanning on Mon, 01 October 2012 05:31
		Re: 3d device coordinates from a 3D polyline.... By: George.millward on Fri, 28 September 2012 14:31
		Re: 3d device coordinates from a 3D polyline.... By: lecacheux.alain on Tue, 02 October 2012 02:22

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