# Colors on a 3D curve not working

I'm having troubles applying colors to a simple 3D curve plot. Here's the code :

Color1 = RGBColor[0, 0, 1];
Color2 = RGBColor[1, 0, 0];
Color3 = RGBColor[0, 1, 0];

CouleurLigne[t_] := Blend[{Color1, Color2, Color3},  Rescale[t, {Tmin, Tmax}]]

Tmin = 0;
Tmax = 4 Pi;

ParametricPlot3D[{Sin[t], Cos[t], t}, {t, Tmin, Tmax}, PlotStyle -> {Directive[AbsoluteThickness[1]]}, ColorFunction -> (CouleurLigne[#] &), MaxRecursion -> 7, PerformanceGoal -> "Quality"]


I'm getting the curve with the first color applied to it. No blending from color1 to color3. What am I doing wrong here ?

• Just a note that your Color1, Color2, Color3 are Blue, Red, Green, respectively. Aug 3 '15 at 16:26

The arguments for ColorFunction in ParametricPlot3D are (from the docs):

ParametricPlot3D x, y, z, u or x, y, z, u, v

so you need #4, which is t.

As for the ColorFunctionScaling, I suggest you to read the docs and experiment a little. But just as a hint, you may eliminate both the ColorFunction -> False option AND the Rescale thing in your CouleurLigne definition to get the same result :)

ParametricPlot3D[{Sin[t], Cos[t], t}, {t, Tmin, Tmax},
PlotStyle -> AbsoluteThickness@2,
ColorFunction -> (CouleurLigne[#4] &), ColorFunctionScaling -> False]


• Wow, thanks for the answer. But why the ColorFunctionScaling -> False option ? And why #4 ?
– Cham
Aug 3 '15 at 1:43