Hi Fabrice,

You could define you own shades of gray (I believe there are at least 
50) by adjusting the rgb values as I've shown below.

definecolor [ name = "verylightgray", r = 0.995, g = 0.995, b = 0.995 ] ;

definecolor [ name = "lightergray", r = 0.55, g = 0.55, b = 0.55 ] ;

draw lmt_shade [

path = (z0--z4--z5--z1--cycle),

direction = "left",

alternative = "linear",

colors = {"lightergray", "verylightgray"},

] xshifted 5cm;

I added it to your code after the lines:

draw z0--z4--z3--cycle;

draw z1--z5--z2--cycle;

draw rectangle;

Hope this helps.

Best Wishes

Keith

On 07/10/2023 16:54, Fabrice Couvreur wrote:
> Hi,
> Sorry for the late response. Thanks for the help. So I read the 
> documents and managed to get a gradient even if it's not exactly like 
> the figure.
> Fabrice
>
> draw lmt_shade [
>               path = (z0--z4--z5--z1--cycle),
>               direction = "left",
>               alternative = "linear",
>               colors = {"black", "lightgray"},
>             ] ;
>
> Le ven. 6 oct. 2023 à 08:27, Henning Hraban Ramm <texml@fiee.net> a 
> écrit :
>
>     While the luametafun (“Metafun XL”) manual is also (meta)fun, I meant
>     the general metafun(-s|-p) manual, the big one (>400 p. in the
>     “print”
>     version, >600 p. in the “screen” version). Recommended!
>
>     Hraban
>
>     Am 06.10.23 um 10:08 schrieb Keith McKay:
>     > Also look at the LuaMetaFun manual chapter 8. In fact the whole
>     manual
>     > is worth a read. I'm sure you find much of use in it.
>     > Best Wishes
>     > Keith
>     >
>     > On Thu, 5 Oct 2023, 20:52 Henning Hraban Ramm, <texml@fiee.net
>     > <mailto:texml@fiee.net>> wrote:
>     >
>     >     Am 05.10.23 um 21:50 schrieb Fabrice Couvreur:
>     >      > Hi,
>     >      > I would like to obtain, if possible, a gray gradient like
>     in the
>     >     image.
>     >      > My code uses Metapost but maybe this is possible with
>     Metafun.
>     >
>     >     Have a look into the Metafun manual, chapter 8.1 “shading”.
>     >
>     >     Hraban
>
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