# [Bf-docboard] Re: sine wave errata

Stefano Selleri stefano.selleri at unifi.it
Tue Oct 18 19:04:50 CEST 2005

```Waoit, no Image is Ok, it is just the text :)

----- Original Message -----
From: Randall Rickert
To: bf-docboard at projects.blender.org
Sent: Tuesday, October 18, 2005 6:45 PM
Subject: [Bf-docboard] Re: sine wave errata

Sorry, looking at it closer, the documentation says:

The actual width of the area in which the single pulse is significantly non-zero in Blender Units is given by 4 over the Narrow Value. That is, if Narrow is 1 the pulse is 4 Units wide, and if Narrow is 4 the pulse is 1 Unit Wide.

It seems this formula should be 4 over twice the Narrow value i.e.: 4/(2*Narrow), not 4/Narrow. I tried different values to get closer to a sine wave, such as Pi/(2*Narrow). It's really not possible to make a sine wave in Blender, because the pulse is a Gaussian function or such, not a sine function. 4/(2*Narrow) makes the wave very smooth, but the peaks are a bit more narrow than the valleys.

My suggestion of Pi/(2*Narrow) looked more like a sine wave, but it makes a subtle crease in the valley. 4/(2*Narrow) is a better formula, and is probably the formula the original author intended when they wrote "4 over Narrow".

-Randall

Date: Mon, 17 Oct 2005 03:27:55 -0700
From: Randall Rickert <randall at rickert-digital.com>
Subject: [Bf-docboard] sine wave errata
To: bf-docboard at projects.blender.org
Message-ID: <8E36C3EA-5636-493F-BA71-51DBFD628C43 at rickert-digital.com>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

It says:

To obtain a Sinusoidal-like wave

To obtain a nice Wave effect similar to sea waves and close to a
sinusoidal wave it is necessary that the distance between following
ripples and the ripple width are equal, that is the Width Num
Button value must be equal to 4 over the Narrow value.

There is a nice diagram also. Both the diagram and the text are
incorrect. The formula Width=4/Narrow does not create something like
a sine wave. This is easy to see if you try using the values Width=4
and Narrow=1. The result does not look at all like a sine wave.

As far as I can tell, the formula for a wave that looks sinusoidal
should be Width=Pi/(2*Narrow). Probably a better way to write it is
wavelength in mind (the wavelength is Width*2).

It's a bad interface anyway, because making a sine wave (probably the
most common wave the user will want to make) shouldn't require the
user to calculate Pi/(2*whatever).

-Randall

------------------------------------------------------------------------------

_______________________________________________
Bf-docboard mailing list
Bf-docboard at projects.blender.org
http://projects.blender.org/mailman/listinfo/bf-docboard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://projects.blender.org/pipermail/bf-docboard/attachments/20051018/0c870dc3/attachment-0001.htm
```