intersection of two triangles

Hi,

I have 2 triangles and I would like to know if they are inside each others or they intersect. Like the picture How I can do that ? I read about polyxpoly but to be honest I don't understand how to use it in this scenario.

Answer 1

[Marta Salas]

    % this define the vertexes (x,y) of first triangle
      trian1x =[ 0 0.5 1 0]; 
      trian1y =[ 0 1 0 0]; 
    % this define the vertexes (x,y) of second triangle  
      trian2x =[ 0 0.25 0.5 0]; 
      trian2y =[ 0 0.5 0 0]; 
    % (xi,yi) are the intersection points  
      [xi,yi] = polyxpoly(trian1x,trian1y,trian2x,trian2y,'unique');

      figure, 
      plot(trian1x,trian1y,'b')
      hold on 
      plot(trian2x,trian2y,'r')
      hold on 
      plot(xi,yi,'*g')

[Sososasa]

Hi Marta,

This gives me the intersection points even when one triangle is lie inside the other. And I only need to get the intersection points if one of them is not contained inside the other.

If I get the intersection point in both situations, then I can not decide if one of them is actually inside the other or not.

[Marta Salas]

You can decide whether it's inside or not checking if the intersection points correspond to the triangle vertexes.

[Sososasa]

Yap I did that thanks a lot :)

[Ines]

Hi If I have the vertexes of two triangles, how can I check if they intersect or not? I need a function that just gives me true if they intersect and false if not. Thanks

[Yash Jangir]

what if there are no intersection points but the triangle is completely inside the other triangle?

Answer 2

[Rushabh Khattri]

I am getting this error :- Undefined function 'polyxpoly' for input arguments of type 'double'.

[Jan]

The first point to start is asking an internet search engine for this term: "Matlab polyxpoly". You will find out, that this command belongs to the Mapping Toolbox: https://www.mathworks.com/help/map/ref/polyxpoly.html. It seems like you do not have a license for this toolbox and then you need a different solution. Please open a new thread then.

[John D'Errico]

This is not an answer. It is only a new question, but resurrecting a zombie question, that is only partially related.