>There can't be any trick to obtain normal of any point in space becouse point
>has no normal vector as you pointed. There can be trick for particular usage
>but then you have to specify where/how you want to use it.

Christoph Hormann <chr### [at] gmxde> wrote:
>The slope pattern is only defined at the surface of the object it is
>applied to.  Therefore you question does not seem to make sense to me.  

Actually I don't want the normal of any point in space, but only on the
surface of an object.
I would like to use the value of a given slope pigment in a function which
should be used to as a pattern for another pigment. So only the value on the
surface of an object using this pigment is needed.
Something like this:

#declare slopePigment = pigment
{
    slope
    ...
}

#declare slopeFunction = function
{
    pigment
    {
        slopePigment
    }
}

#declare anotherFunction = function(x,y,z)
{
    ...slopeFunction(x,y,z)...
}

object
{
    anObject

    pigment
    {
        function
        {
            anotherFunction(x,y,z)
        }
    }
    ...
}

Or is there any other way doing something similar?

>Using intersection information with an arbitrary object is of course an
>interesting concept for a pattern or function.  See:
>
>http://www-public.tu-bs.de:8080/~y0013390/povcyg/docu/docu_pattern01.html#OBJSLOPE
>
>for an example.  It might be that in the future 'trace' will be made
>available in functions too but not in Povray 3.5.

That's exactly what I was looking for. A shame it's not supported by 3.5.

theVIPER

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