python move a shape in zigzag-CodePudding

I want to write a code that moves a sphere in a zig-zag way across the screen from the upper left to the lower right. this is my attempt.

scene= canvas(width=500, height=500, autoscale=False)
xpos=-10
ypos=8
totaldistance=15
stepsize=0.1
nsteps=int(totaldistance/stepsize)
totaltime=20
timebetween=int(nsteps/totaltime)
s=sphere(pos=vector(-10,0,0), axis=vector(0,2,0))
for i in range(nsteps):
    rate(timebetween)
    xpos=xpos stepsize
       xpos=xpos stepsize
    if xpos==10:
        xpos=xpos-stepsize
    if xpos==1:
        xpos=xpos stepsize 
    ypos=ypos-stepsize
    s.pos=vector(xpos,ypos,0)

I don't know how to tell the sphere to move in the other direction when it reaches certain position so that it forms a zig zag motion.

CodePudding user response：

Popular method is to change direction

stepsize = -stepsize

And it needs to use separated x_stepsize and y_stepsize

like this

x_stepsize = stepsize
y_stepsize = -stepsize

for i in range(nsteps):
    xpos  = x_stepsize
    ypos  = y_stepsize

    if xpos >= 10:
        xpos = 10
        x_stepsize = -x_stepsize
    if xpos <= 1:
        xpos = 1
        x_stepsize = -x_stepsize

    s.pos = vector(xpos, ypos, 0)