demodercrv.m

非均匀有理B样条的matlab程序

function demodercrv
% Demonstrates the construction of a general
% curve and determine of the derivative.
%

% D.M. Spink
% Copyright (c) 2000

% make and draw nurbs test curve
crv = nrbtestcrv;
nrbplot(crv,48);
title('First derivatives along a test curve.');

npts = 9;
tt = linspace(0.0,1.0,npts);

dcrv = nrbderiv(crv);

% first derivative
[p1, dp] = nrbdeval(crv,dcrv,tt);

p2 = vecnorm(dp);

hold on;
plot(p1(1,:),p1(2,:),'ro');
h = quiver(p1(1,:),p1(2,:),p2(1,:),p2(2,:),0);
set(h,'Color','black');
hold off;