Re: Coloring function

*To*: mathgroup at smc.vnet.net*Subject*: [mg121478] Re: Coloring function*From*: Heike Gramberg <heike.gramberg at gmail.com>*Date*: Fri, 16 Sep 2011 05:49:47 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201109150837.EAA29104@smc.vnet.net>

It probably helps to specify ColorFunctionScaling->False. With ColorFunctionScaling->True (which is the default setting) the arguments of the ColorFunction are scaled to lie between 0 and 1. When ColorFunctionScaling is False, the actual values of x, y, and z are used. Note that since RGBColor expects its arguments to be between 0 and 1, you would then need to rescale Abs[x] or x^2+y^2 in your examples by hand. So for your examples you would get ListPointPlot3D[ Flatten[Table[{i, j, 0}, {i, -30, 30}, {j, -30, 30}], 1], ColorFunctionScaling -> False, ColorFunction -> Function[{x, y, z}, RGBColor[Abs[x]/30, 0, 0]]] and ListPointPlot3D[ Flatten[Table[{i, j, 0}, {i, -30, 30}, {j, -30, 30}], 1], ColorFunctionScaling -> False, ColorFunction -> Function[{x, y, z}, RGBColor[(x^2 + y^2)/(30^2 + 30^2), 0, 0]]] Heike. On 15 Sep 2011, at 10:37, guiwi wrote: > Hi everybody. I have a general problem with the coloring method of > ColofFunction. Let's consider a plane of points that one wants to plot > with ListPointPlot3D. If I want to color the points according to their > x position, I write: > > ListPointPlot3D[Flatten[Table[Table[{i, j, 0}, {j, -30, 30}], {i, -30, > 30}], 1], ColorFunction -> Function[{x, y, z}, RGBColor[x, 0, 0]]] > > and that indeed works. But if I want to color according to the > absolute value of x and use > > ColorFunction -> Function[{x, y, z}, RGBColor[Abs[x], 0, 0]] > > the coloring is not symmetrical around the x=0 position, but > identical to the previous case. Another problem is to obtain a radial > coloring with > > ColorFunction -> Function[{x, y, z}, RGBColor[x^2+y^2, 0, 0]] > > where the origin of the radial coloring is not at {0,0} but somewhere > on the edge of the plot. Anyone knows how to control that coloring ? > Thanks. > Guillaume >

**References**:**Coloring function***From:*guiwi <guillaume.witz@yahoo.com>