Computer Aided Design : 5681


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Subject:	Re: VB - parts and transformation matrices, Z-ordering, optional lines, bow-tied quads - help!
Newsgroups:	lugnet.cad
Date:	Tue, 27 Mar 2001 16:56:41 GMT
Viewed:	610 times

Daniel Crichton wrote: > > You are probably Pos-Multiplying the modeling Matrix, instead of > > Pre-Multiplying. > > I had that problem too ! > > OK, you've lost me here - I just applied the matrix calculation as-is from > the FAQ. What is the difference between Pos- and Pre- multiplying? Imagine you have Modeling Matrix M and another matrix A to multiply it by, like when you use command 1 (one, include of another .DAT file) And you want to keep the final Matrix as a New modelling Matrix (NM) so, you must be doing NM = M . A you should be doing NM = A . M Since Matrix multiplication is not commutative, the result is different. Hope that helps. See ya Rui Martins

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		Re: VB - parts and transformation matrices, Z-ordering, optional lines, bow-tied quads - help!
Fixed it! When running the coords through the matrix I wasn't storing the new values in a separate array, so when it came to calculating the new Z coord on the 4-4ndis.dat and 4-4disc.dat parts I was using the translated X and Y coords in the calc (...) (24 years ago, 28-Mar-01, to lugnet.cad)

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		Re: VB - parts and transformation matrices, Z-ordering, optional lines, bow-tied quads - help!
(...) Maybe, maybe not - I'm trying to build something that will help me draw complicated patterns on existing parts, such as the Darth Maul pattern (75% done). (...) OK, you've lost me here - I just applied the matrix calculation as-is from the (...) (24 years ago, 27-Mar-01, to lugnet.cad)

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