Re: A89: Re: 3D rotation of plots


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Re: A89: Re: 3D rotation of plots




So, for moving 3D text much like the Windows98 screen saver, I would use something like:
x'=1*x + cosT*x + 0*y + 0*y + 0*z + sinT*z
y'=0*x + 0*x + cosR*y + 1*y + sinR*z + 0*z
z'=0*x + -sinT*x + -sinR*y + 0*y + cosR*z + cosT*z

where R is my angle around the x-axis, and T is my angle around the y-axis.  Would this work?

-Miles Raymond      EML: m_rayman@bigfoot.com
ICQ: 13217756       IRC: Killer2        AIM: MRayMan
http://www.bigfoot.com/~m_rayman/

-----Original Message-----
From: Nate Mueller <nlmueller@students.wisc.edu>
To: assembly-89@lists.ticalc.org <assembly-89@lists.ticalc.org>
Date: Wednesday, January 13, 1999 5:00 PM
Subject: Re: A89: Re: 3D rotation of plots


>>Wouldn't it be easier to display it like this:
>>
>>around x-axis:
>>x'=1*x + 0*y + 0*z
>>y'=0*x + cosT*y + sinT*z
>>z'=0*x + -sinT*y + cosT*z
>>
>>around y-axis:
>>x'=cosT*x + 0*y + sinT*z
>>y'=0*x + 1*y + 0*z
>>z'=-sinT*x + 0*y + cosT*z
>>
>>around z-axis:
>>x'=cosT*x + sinT*y + 0*z
>>y'=-sinT*x + cosT*y + 0*z
>>z'=0*x + 0*y + 1*z
>
>Yes, this would be easier in straight asm.  However, if someone made a
>matrix multiply function it would be much simpler to use matrix multiply.
>The matrix system is also faster if you want to perform more then one
>transformation at a time.  You simply add the two transformation matrixs
>and multiply that matrix by the list of points.  There is no savings of
>time to do one transformation, but doing n transformation is n times as
>fast with the matrix method.
>
> --Nate


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