So, I am trying to make a realistic bouncing function, where the turtle hits a wall and bounces off at the corresponding angle. My code looks like this:
def boun
Gday,
Your problem seems to be that you are using the same trigonometry to calculate the right and left walls, as you are the top and bottom. A piece of paper and a pencil should suffice to calculate the required deflections.
def inbounds(limit, value):
'returns boolean answer to question "is turtle position within my axis limits"'
return -limit < value * 2 < limit
def bounce(num_steps, step_size, initial_heading):
'''given the number of steps, the size of the steps
and an initial heading in degrees, plot the resultant course
on a turtle window, taking into account elastic collisions
with window borders.
'''
turtle.reset()
height = turtle.window_height()
width = turtle.window_width()
turtle.left(initial_heading)
for step in xrange(num_steps):
turtle.forward(step_size)
x, y = turtle.position()
if not inbounds(height, y):
turtle.setheading(-turtle.heading())
if not inbounds(width, x):
turtle.setheading(180 - turtle.heading())
I've used the setheading
function and a helper function (inbounds
) to further declare the intent of the code here. Providing some kind of doc-string is also good practice in any code that you write (provided the message it states is accurate!!)
Your mileage may vary on the use of xrange
, Python 3.0+ renames it to simply range
.
Try something like this:
if not (left <= x <= right):
turtle.left(180 - 2 * turtle.heading())
elif not (bottom <= y <= top):
turtle.left(-2 * turtle.heading())
else:
pass
My python syntax is a little rusty, sorry :P. But the math is a little different for a horizontal vs. a vertical flip.
EDIT:
I suspect that what is happening is your turtle is getting into a situation where it is pointing upwards and stuck above the top wall. That would lead it to just flip indefinitely. You could try adding the following conditions:
if (x <= left and 90 <= turtle.heading() <= 270) or (right <= x and not 90 <= turtle.heading() <= 270):
turtle.left(180 - 2 * turtle.heading())
elif (y <= bottom and turtle.heading() >= 180) or (top <= y and turtle.heading <= 180):
turtle.left(-2 * turtle.heading())
else:
pass
If that works, there is probably a bug elsewhere in your code. Edge handling is tricky to get right. I assume that turtle.heading() will always return something between 0 and 360 - if not then it will be even more tricky to get right.