Well , i have try to uderstand .was difficult ..

Well if i understand well ..

when you got one of x,y upper than one you got a 1 ... (insteed of 0??)

well i thing that commes from your once term in your pigment function ..

when x is upper than one then you are 'ouside' your image map than that take
the value one (probably due to outside of the imagemap is white (1) ))

same for y upper than one ..



..


did that help you ?

























news:web.44a3c005a26efc189e4a59f60@news.povray.org...
> Hello there,
>
> Is it a bug or (most probable) did I miss something ?
>
> I have this very nice image of a checker (this is just for the sake of the
> example and not the image I am actually using) stored in a file called
> test.pgm:
> content of test.pgm:
> P2
> 2 2
> 255
> 0 100
> 100 0
>
> I am using this image in a pigment function, or whatever you might want to
> call that:
> #local fn_pig= function {
>   pigment {
>     image_map {
>       pgm "test.pgm"
>       map_type 0
>       interpolate 0
>       once
>     }
>   }
> }
> #local fn_pig_Height=function { (fn_pig(x, y, 0).red ) }
>
> Then, I just call this function many times, using a loop:
> #declare Pas = 0.1;
> #declare Loc_x = 0;
> #while (Loc_x < 1)
>   #declare Loc_y = 0;
>   #while (Loc_y < 1)
>     #debug concat("x=",str(Loc_x,3,3)," y=",str(Loc_y,3,3)," fn_pig_Height
=
> ",str(fn_pig_Height(Loc_x,Loc_y,0),5,5),"n")
>     #declare Loc_y = Loc_y + Pas;
>   #end
>   #debug "n"
>   #declare Loc_x = Loc_x + Pas;
> #end
>
> and HERE IS MY QUESTION !!! For each x value strictly lower than 1, and
for
> each y value stricly lower than 1 (x<1 and y<1), I get what I expect (0 or
> 0.39216, which is 100/255, depending on x and y). But, for x=1 and
> y=anything, or for y=1 and x=anything, I get the value 1 !!
> When I render this as an isosurface, I get a kind of wall around my
> checker...
> Could anyone help me out ?
>
> Hope my description is clear. If not, please ask for more information...
>
> S.
>
>

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