selecting a triangle in an array of delaunay points
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The code explains it all.
Try to run it, it might give you a good result, but that would be random.
This code is supposed to display a point, and color the nearest triangle green. It does not do this, and gives "nan" errors on seemingly random iterations of the loop.
I would appreciate some help :)
clc;
clear all;
close all;
P = [ 2.5 8.0
6.5 8.0
2.5 5.0
6.5 5.0
1.0 6.5
8.0 6.5];
dt=delaunayTriangulation(P);
triplot(dt);
hold on
%%example functions
dt.Points
dt.ConnectivityList
%abs vals x
a=min(P(:,1))
b=max(P(:,1))
%abs vals y
c=min(P(:,2))
d=max(P(:,2))
for n=1:5
random_x=a + (b-a).*rand(1);
random_y=c + (d-c).*rand(1);
triangleId=pointLocation(dt, random_x,random_y) %select the triangle ID of the triangle closest to the point generated by the random generator
scatter(random_x,random_y) %display the points
%%now... the part that does not work
%%selecting the right triangle and turning it a different color
tri = dt(triangleId, [1:end 1]);
patch(P(tri,1), P(tri,2), 'r', 'LineWidth',1, 'FaceColor','g')
end
6 Comments
John D'Errico
on 17 Dec 2014
My point is, pointLocation will return NaN in that case. SURPRISE!
How often will that event happen? As it turns out, that should happen roughly 21.429% of the time that a point falls outside of your triangulated region, but inside the rectangle that you use to generate the random points.
(1 - (8-2.5)*3/(3*(8-1)))*100
ans =
21.429
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