Hi Bob,

Bob Hughes wrote in message <36A6D414.9DB0639D@aol.com>...
>This reminds of when I used to draw out planetary ellipses rather
>crudely in 2 dimensions with GW Basic. I've forgotten everything about
>it pretty much.
>This:
>
>translate <Radius1*sin(2*pi*clock),0,Radius2*cos(2*pi*clock)>
>
>might also be used like:
>
>translate
><OffsetX+(RadiusX*sin(2*pi*clock)),0,OffsetZ+(RadiusZ*cos(2*pi*clock))>
>
>where the offsets are coordinates to center upon, and may also be used
>as:
>
>#declare OffsetRadiusX=3 //example
>#declare OffsetRadiusZ=1.5 //example
>
>#declare OffsetX=OffsetRadiusX*sin(2*pi*clock)
>#declare OffsetZ=OffsetRadiusZ*sin(2*pi*clock)
>
>Then the final translation vector.
>
>translate <OffsetX*sin(2*pi*clock)),0,OffsetZ*cos(2*pi*clock))>
>
>This should make the "orbit" revolve upon an orbiting center of mass, as
>it were. Which is how the Earth and Moon do, in a slight way.
>
>Perhaps finally a third (smaller offset) component of the translate
>vector, Y, could perturb this also making for an inclined (and wavy if
>the clock is times 2 for example) orbital plane.
>
>Or am I way off base with this whole suggestion?
>I'm guessing about it, so none of this may be useable.


No,no,no, this is great. I really ought to learn how to use sin/pi etc

Tata

Andy C

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