How i can draw a 3D vector with MATLAB and move it along a parabola?

Question

I'm asking the same question of some days ago but now i would like to add at the question one more step.

Below the code for the first step:

t = -20:0.1:20; 
plot3(zeros(size(t)),t,-t.^2);
hold on
i = 1;
h = plot3([0 0],[0 t(i)],[0 -t(i)^2],'r');
for(i=2:length(t))
    set(h,'xdata',[0 0],'ydata',[0 t(i)],'zdata',[0 -t(i)^2]);
    pause(0.01);
end

Now I draw a second vector, fixed in the space, with the same origin of the moving vector, say [0 0 0] and the end at, e.g., [0 0 30]. Than there is an angle between the two vector, having the same origin.

My questions: I would like to calculate the bisector of this angle and show how the bisector moves in the space, in connection to the motion of the first vector.

Thanks for the help

Answer 1

Use a new handler (g for example) to store the "plot3" for the bisector.

On each step calculate the bisector equation and use "set" to update the handler g (as you are doing it for h).

EDIT :

To compute the bisector :

U = [1 2 3];
V = [4 5 6];
B = U / norm(U) + V / norm(V);
B = B / norm(U); % Bisector is now of norm 1
B = B * norm(U); % easier for plotting, bisector and U and now equal norms