In article <3c9e1c9f@news.povray.org>, bob h wrote:
>---snip---
> (Notice that you accidentally made the clipping box for the normal extend
>to -20 and it needs to be 0 so the two planes show. Just so people know
>that.)
>---snip---

I'm sorry.

>The number_of_waves global setting usually controls this, not frequency.

No, number_of_waves controls number of waves (i.e wave
centers), while frequency controls their frequency.

> Of
>course that doesn't apply to non-ripples and non-waves patterns.
>Consider the following, taking your example and changing it a bit:
>
> global_settings {
>        number_of_waves 5
> }
>
>  camera { location <0, 20, -30> look_at <0, 0, 0> }
>  light_source { <30, 30, -30>, 1 }
>
>  plane {
>    y, 0
>    pigment { ripples sine_wave frequency 2 scale 5 }
>    clipped_by { box { <-20, -1, -20> <0, 1, 40> } }
>  }
>
>  plane {
>    y, 0
>    pigment { rgb .7 }
>    normal { ripples 7 sine_wave frequency 2 scale 5 }
>    clipped_by { box { <0, -1, -20> <20, 1, 40> } }
>  }
>
>This shows wave_type matters as well, but anyhow I can get a close match. If
>there's truly a problem or difficulty in the usage of frequency I couldn't
>say if it matters or not. This is just my observation at the moment.

Using sine_wave and integer frequency _hides_ the problem,
but it's still there.  sine_wave makes the pigment smooth,
not right (and it distorts the wave shapes, one has to use
asin()-like colour_map to get original shapes).  Just try
frequency 1.5 instead of 2 in your example and you'll see
what I mean.

However, one perhaps could get by with your solution in most
practical cases.

Yeti

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