Animate a ball in 3 dimensions

I want to animate a ball travelling in 3-D space along a parametrized curve, say a helix. In 2-D space, I use the 'viscircles' function to draw a circle at a specific point and fixed radius. This is very easy to loop:

 %ball travelling in 2-D space along a circle of radius 1
 t = 0:0.01:2*pi;
 x = cos(t);
 y = sin(t);
  for i=1:length(t)
    ballpoint = [x(i) y(i)];
    ball = viscircles(ballpoint,0.05) %draws circle of radius 0.05 at point 'ballpoint'
    drawnow
  if i<length(t) %deletes ball at position (x(i),y(i)) when ball is at position (x(i+1),y(i+1))
    delete(ball);
  end
  end

the code above is very simple and straightforward. I thought there would be an analogous function of the same sort as 'viscircles' that would draw a sphere about a point and fixed radius, but there isn't. How could I make a similar animation as the one above, only in 3-D space with a sphere travelling on a helix?

Answer 1

[KSSV]

t = linspace(0,6*pi,100);
r = 1. ;   % radius of spiral path 
c = 2 ;     
x = r*cos(t) ;
y = r*sin(t) ;
z = c*t ;
for i = 1:length(x)
    plot3(x,y,z,'Color','k','Linewidth',1) ;
    hold on
    plot3(x(i),y(i),z(i),'Or','Markersize',10) ;
    hold off
    drawnow
end

[Denis Kartachov]

Thank you! So does 'O' draw a sphere at the point x(i) y(i) z(i)? is 'r' the radius?

[KSSV]

Yes 'r' is radius. 'O' this draws circle. Check sphere to draw a sphere. Read Jan Simon advice.

Answer 2

[Jan]

The command sphere draws a sphere. For a smooth animation you can create the sphere outside the loop or in the first iteration only, and set the 'XData', 'YData', and 'ZData' properties afterwards only.