MATLAB: How to Setting Custom Colours in 4D figures (Slice Function)

Question

 [x,y,z] = meshgrid(-2:.2:2,-2:.25:2,-2:.16:2);
v = x.*exp(-x.^2-y.^2-z.^2);
xslice = [-1.2,.8,2]; yslice = 2; zslice = [-2,0];
slice(x,y,z,v,xslice,yslice,zslice)

I want to change the colour according the value of v.

Answer 1

The color right now is changed according to v...

That's why the color in the middle shows up.

More per clarification

Build another array, C, that will be an index into the colormap:

[x,y,z] = meshgrid(-2:.2:2,-2:.25:2,-2:.16:2);
v = x.*exp(-x.^2-y.^2-z.^2);
xslice = [-1.2,.8,2]; yslice = 2; zslice = [-2,0];
%

%v<0, blue; 0<=v<0.2, green; 0.2<=v, red.
%
C = ones(size(v)); %blue
C((v > 0) & (v < 0.2)) = 2; %green
C(v>=0.2) = 3; %red
colormap([0 0 1;0 1 0;1 0 0]); %bgr
slice(x,y,z,C,xslice,yslice,zslice)