 | | Unusual View matrices in LDRAW.INI
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Hey, does anybody out there know the origin of the "Oblique", "UpsideDown", and "Natural" viewing matrices in LDRAW.INI. I'm not sure whether these came from LDAO, LDLITE, or perhaps even LDRAW? Wherever they came from, they don't seem to be pure (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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(...) I don't know their origin, but you're right, there's a shear component in them. Here's what a matrix decomposition shows: (...) Scale : (1.5, 0.942809, 1.41421, 0) Rotate : (0.321751, 0.729728, 0.463648, 0) Translate : (0, 0, 0, 0) Shear : (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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I believe the matrix happens to produce a standard isometric view, but doesn't do so in the traditional 3D graphics way of rotation. This means that in addition to not looking right after rotation, it also doens't produce correct results when you (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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OK now we're getting somewhere. Thanks for providing the exact mathematical representations of those numbers. Now I'm gonna have to figure out how you calculated them. :-) (I just had the computer do the work and print out the decimal (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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(...) LDAO writes those entries to ldraw.ini. I'm not sure if any other programs update that section or not. The "Oblique" view is the default view for LDraw, and was also used for LDLite (I think) and L3Lab. "UpsideDown" is derived from "Oblique". (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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I knew there was a way to decompose the matrices! But I couldn't find it. Where is that written down? I also thought there was a way to remove the cumulative round off errors in a transformation matrix after many matrix multiplications. Do you (...) (24 years ago, 4-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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(...) In L3Lab, you can find the current view matrix in the statistics menu item. It is useful for usage with, e.g., LDLITE and LDraw. Fredrik (24 years ago, 5-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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"Don Heyse" <dheyse@hotmail.spam....away.com> wrote in message news:G1xC6x.7nK@lugnet.com... (...) mathematical (...) you (...) the (...) To be perfectly honest, I can't really remember how I came up with them. I think I actually started with the (...) (24 years ago, 5-Oct-00, to lugnet.cad.dev)
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| | Re: Unusual View matrices in LDRAW.INI
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(...) It's from Graphics Gems II, the code for which is available online (linked from (URL) ). (...) That's called (re-)orthogonalization. Graphics Gems I has code to do it. You might also reconsider whatever it is that's causing the matrix to (...) (24 years ago, 5-Oct-00, to lugnet.cad.dev)
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