In article <3d578f54@news.povray.org> , "Thorsten Froehlich" 
<tho### [at] trfde> wrote:

> Easy:  The code handling vector functions assumes three or more return
> values and acts a bit strange when dealing with only two.  The way you
> declare the spline you create a two diemensional spline, which is what
> causes the odd effects.  Add a 3D vector to the spline and it goes away.

To be more precise, the spline function evaluator for functions - that is,
the internal spline function f_spline in fnintern.cpp - assumes the location
of the parameter is always the fourth stack entry.  This effectively
supports only 3D vectors (support for other vector sizes was added only
recently).  To change it, change the line in spline from

Get_Spline_Val((SPLINE *)(f->private_data), PARAM_N_X(3), Result, &Terms);

to

Terms = ((SPLINE *)(f->private_data))->Terms;
Get_Spline_Val((SPLINE *)(f->private_data),PARAM_N_X(Terms),Result,&Terms);

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

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