"David Necas (Yeti)" <yet### [at] monocerosphysicsmunicz> wrote in message
news:slr### [at] monocerosphysicsmunicz...
> Not exactly a bug, but still needs fixing:

Not so sure, myself.

> The `frequency' keyword is used for two completely different
> things
> - in colour_maps to specify how many times they should be
>   mapped over the [0,1] interval
> - in ripples and waves patterns to specify the wave
>   frequency
---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---
> As normals (right), the ripples are OK, but as pigment
> (left) they are broken, because `frequency' was used for
> both wave frequency and colour_map frequency.
>
> I suggest using a separate keyword like `wave_frequency' or
> so for wave frequencies.  Consider one can't use ripples
> in isosurface now (well, can, but can't set frequency).

The number_of_waves global setting usually controls this, not 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.

bob h

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