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Samuel Benge wrote:
> Bill Pragnell wrote:
>> Nice image, all the nicer for the colour bleeding!
>
> Thanks!
>
>> Surely the Miller indices define the crystal planes,
>
> Yes....
>
>> so you can use them
>> directly to define your intersection planes (i.e., no knowledge of angles
>> required)?
>
> No. I wish that were true, because it would make everything much easier.
> Now, it *might* be true for cubic crystal systems, but I have to check
> on that. For hexagonal systems that theory just doesn't hold.
>
> Look at the attached image. If we were talking just straight normals
> here, the numbers would be decimals or very large integers. Instead, we
> have angles represented by three small integers, ranging between -1 and
> 1 (they can be higher, I've seen them as high as 6).
>
> I don't understand how the Miller indices work, but I know it has to do
> with how molecules in the crystal are offset from one another. The
> Wikipedia article just confused me, as I have no formal training in
> higher mathematics.
>
> If you have a way to calculate the normals for single faces (not the
> angle between two faces), by all means, let me know! Otherwise, I'm off
> to try the answer via Google....
>
> Sam
>
> ------------------------------------------------------------------------
>
From your example image:
intersection {
plane {
Miller.x * <1/sqrt (2), 0.5, 0> + Miller.y * <0, 1, 0>,
1 / sqrt (2)
}
...
}
But I don't know how the third number works, nor if it will hold
for Miller values other than +/-1...
Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
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