Hi IMO it would be a nice feature if the function "distanceLines3d"

distanceLines3d: Additional ouput: points on the line about matgeom HOT 4 CLOSED

mattools commented on May 27, 2024

distanceLines3d: Additional ouput: points on the line

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Comments (4)

dlegland commented on May 27, 2024

Hi,

I agree, this would be nice!
I had a quick look, but this does not seem that straightforward...
I add the task on my TODO list!

regards

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oqilipo commented on May 27, 2024

Here is some code. But it works only if the two line matrices have the same size in the first dimension

clearvars; close all

line1 = [0 -25 -50 0 0 1; 25 25 0 1 1 0.5];
line2 = [0 -50 0 1 0 0; -50 0 50 1 0 2];

a = dot(line1(:,4:6),line1(:,4:6),2);
b = dot(line1(:,4:6),line2(:,4:6),2);
e = dot(line2(:,4:6),line2(:,4:6),2);

den = a.*e-b.*b; % 0, if lines are parallel
r = line1(:,1:3)-line2(:,1:3);
c = dot(line1(:,4:6),r,2);
f = dot(line2(:,4:6),r,2);

s = (b.*f - c.*e)./den;
t = (a.*f - c.*b)./den;

pt1 = line1(:,1:3) + line1(:,4:6).*s;
pt2 = line2(:,1:3) + line2(:,4:6).*t;

figure
xlim([-100, 100]),ylim([-100, 100]),zlim([-100, 100])
hold on; grid on
xlabel x; ylabel y; zlabel z;
drawLine3d(line1,'b')
drawLine3d(line2,'r')
drawPoint3d(pt1);
drawPoint3d(pt2);
view(3)
axis equal

distanceLines3d(line1, line2)
distancePoints3d(pt1, pt2)

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dlegland commented on May 27, 2024

thanks,
I'll add it ASAP.

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dlegland commented on May 27, 2024

Hi,
I have added a fix. You can use the following syntax:
[d, pt1, pt2] = distanceLines3d(line1, line2);

I think the code can be improved , but it seems to work.
regards,
David

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