POV-Ray : Newsgroups : povray.beta-test : v3.8b2. height_field input values at 0.0 not clean. : Re: v3.8b2. height_field input values at 0.0 not clean. Server Time
2 Mar 2024 02:59:16 EST (-0500)
  Re: v3.8b2. height_field input values at 0.0 not clean.  
From: William F Pokorny
Date: 17 Feb 2023 05:11:09
Message: <63ef52bd$1@news.povray.org>
On 2/16/23 18:45, Kenneth wrote:
> Yes. Functions as used in height_fields never see called x,y values
> outside the [0-1] range.

Perhaps worth saying a little more than the above. Whether creating a 
height_field or internal image_map from a function in POV-Ray, any 
'function return' values outside the [0-1] get 'wrapped' to a ramp wave 
as is the default with the majority of inbuilt patterns.

So, function return values of:
-0.1 --> 0.9
-0.5 --> 0.5
-0.9 --> 0.1.
1.1 --> 0.1
1.5 --> 0.5
1.9 --> 0.9

In other words, there is a jump or discontinuity when returning values 
go negative or larger than 1. Further, there is no ability to to invoke 
wave(a) modifiers as is true with the pattern mechanism.

Function based image_maps and height_fields all end up in a [0-1] 
vertical/value range - even if your function itself returns values 
outside that range.

Bill P.

(a) - The povr fork offers some wave modification capability via new 
inbuilt functions like f_sine_wave().

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