Pencils

on 15 Oct 2022

% Pencils

% Compute ideal # of vertices so we get sharp points

%nb = 8; % number of bumps

%vpb = 100; % vertices per bump. Odd makes tops flat, even sharp

%n = nb*vpb+1 % total number of vertices. +1 for last vertex matching the first.

t=linspace(0,2*pi,801);% linspace(0,2*pi,n);

% Mesh

r=linspace(0,1,2);

[R,T]=ndgrid(r,t);

% Unit Wave function (7=nb)

M=(1-mod(T*8,2*pi)/pi);

W=rescale(1-(M.^2-1/3).^3,.2,1);

% Apply wave to R

S=R.*W;

% Vertices for a disk with wave applied

X=S.*cos(T);

Y=S.*sin(T);

surface(X,Y,X*0,R,FaceC='i',EdgeC='k',FaceA='i',AlphaData=M.^2,Mesh='r');

% Re-use r from the 'radius' computation to create a pinkish colormap.

colormap([.1 .1 .1

.8 .7 0

1 1 0]);

alphamap(.5:.01:1);

axis equal off