3d emulation with tikz

I am trying to draw a 3d arbitrary volume using tikz.
The 2d equivalent is like(courtesy: this):

tikz

beginframe
begintikzpicture
pgfmathsetseed3
draw[fill=blue!70] plot [smooth cycle, samples=8,domain=1:8]
(x*360/8+5*rnd:0.5cm+1cm*rnd) node at (0,0) ;
endtikzpicture
endframe


Is it possible to give it a 3d feeling? like a diffused lighting effect or something?

2 Answers
2

Here is an option using shade and the ball preset

shade

ball

documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
pgfmathsetseed3
shade [ball color=blue!70] plot [smooth cycle, samples=8,domain=1:8]
(x*360/8+5*rnd:0.5cm+1cm*rnd);
endtikzpicture
enddocument


Some more examples

documentclass[tikz,margin=0.5cm]standalone
begindocument
begintikzpicture
pgfmathsetmacroS3
foreach X in 1,...,3
foreach Y in 1,...,3
beginscope[shift=(S*X,S*Y)]
shade [ball color=blue!70] plot [smooth cycle, samples=8,domain=1:8]
(x*360/8+5*rnd:0.5cm+1cm*rnd);
endscope


endtikzpicture
enddocument


A very small addendum to Milo's great answer: sometimes you want the bright spot not to be where shade[ball color=...]... puts it. You could either define your own shading, or, what is perhaps simpler, clip a circle with a shifted center against that shape. The following animation is supposed to give you an idea what's possible. In the end, you will have to decide on your own what looks realistic, or switch to asymptote, which computes realistic shadings for you.

shade[ball color=...]...

asymptote

documentclass[tikz,margin=0.5cm]standalone
begindocument
foreach X in 1,2,...,42
begintikzpicture
pgfmathsetseedX
path[use as bounding box] (-4,-4) rectangle (4,4);
clip plot [smooth cycle, samples=8,domain=1:8]
(x*360/8+5*rnd:0.5cm+1cm*rnd);
shade [ball color=blue!70] (0.5+rnd,-0.5+rnd) circle (3cm);
endtikzpicture
enddocument


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