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I am new to Mathematica, and I am currently using it to plot 3D figures. My problem is when I use Graphic3D with Specularity and try to add color gradient on top of the 3D object (in my case, a tube) using Glow function.

Graphics3D[{Glow@ColorData["CandyColors"][#] & /@ Table[1/i, {i, 100}],
   Tube[BSplineCurve[KnotData[{3, 1}, "SpaceCurve"] /@ Subdivide[0, 2 Pi, 100],
     SplineClosed -> True], .4]},
   Boxed -> False]

The color somehow just doesn't show.

Update

I also tried to use

Graphics3D[{Directive[Glow[ColorData["CandyColors"][#]],
  Specularity[White, 10]] & /@ Range[1, 100],
    Table[Tube[BSplineCurve[KnotData[{3, 1}, "SpaceCurve"] /@ Subdivide[0, 2 Pi, 100],
      SplineClosed -> True], .4], {i, 1, 100}]},
    Boxed -> False]

with Directive. Also doesn't work.

Can someone please tell me what went wrong in this case?

PS: I want something like this enter image description here

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  • $\begingroup$ If you're using a Mathematica notebook, you should be able to tell that your '#' in the KnotData is pink, meaning it's not associated with a function. You need # followed by & somewhere. I think you meant KnotData[#, "SpaceCurve"] & After this you'll then get errors because # will get filled in with a number from the Subdivide and KnotData doesn't take a number like that. You probably meant KnotData["Trefoil", "SpaceCurve"] /@ Subdivide[0, 2 Pi, 100] $\endgroup$
    – flinty
    Commented Jul 30 at 11:01
  • $\begingroup$ @flinty Sorry for the confusion. I edited the question so that now the command correctly produces the problem I mentioned. $\endgroup$
    – kiz
    Commented Jul 30 at 12:01

1 Answer 1

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Using BSplineFunction instead of BSplineCurve allows the use of ColorFunction. Something like this:

f = BSplineFunction[
  KnotData[{3, 1}, "SpaceCurve"] /@ Subdivide[0, 2 Pi, 100], SplineClosed -> True];

ParametricPlot3D[f[x], {x, 1, 100}, Axes -> False, Boxed -> False, 
 AspectRatio -> 1, PlotStyle -> Tube[.5], 
 ColorFunction -> "CandyColors", PlotRange -> 3.5, 
 Lighting -> {SpotLight[White, ImageScaled[{1, 1, 1}], 1], 
   SpotLight[White, ImageScaled[{1, 1, 1}], 1]}]

enter image description here

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  • $\begingroup$ Thanks a great deal for your answer. However, when I tried to plot for other knots ({4,1} and {6,3} etc.), the tube either broke or got flat in multiple regions. I adjusted the value for the B-spline range and tube radius, but the resulting plot is just not as good as Tube[BSplineCurve[KnotData[{6,3}, "SpaceCurve"] /@ Subdivide[0, 2 Pi, 100]. Is there a neat way of dealing with this? Thanks in advance for your help: ) $\endgroup$
    – kiz
    Commented Jul 31 at 5:30
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    $\begingroup$ @kiz For KnotData[{6,3}, "SpaceCurve"] this method works perfectly for me, just set PlotRange -> 7.5 $\endgroup$
    – yarchik
    Commented Jul 31 at 19:39
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    $\begingroup$ @yarchik That indeed solves it. Thanks! I tried to use PlotRange -> All with Specularity and Glow, but the glow was too bright that it appeared to be a breakage. The resulting plot is a bit too squeezed but I think changing the viewing angle would do the job for now. Thanks again for your help! $\endgroup$
    – kiz
    Commented Aug 1 at 3:24

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