如何使中心点成为我的正方形的中心?

Question

如何使中心点成为我的正方形的中心?现在它变成了角落:

def draw_square(t, center_x, center_y, side_length):

"""
Function draw_square draws a square

Parameters:
t = reference to turtle 
center_x = x coordinate of the center of  square
center_y = y coordinate of the center of  square
side_length = the length of each side

Returns:
Nothing
"""

t.up() #picks up tail of turtle
t.goto(center_x, center_y) #tells turtle to go to center of command
t.down() #puts tail down 

for sides in range(4): #creates loop to repeat 4 times
t.left(90) #turns left 90 degrees
t.forward(side_length) #move forward the length given

def main(): #defines main function

import turtle #imports turtle module 

t = turtle.Turtle() #attaches turtle to t

draw_square(t, 100, 100, 75) #uses the value to make square

main() #calls function

Answer 1

解决方案是简单的几何，不涉及正弦和正割。只需计算一半的side_length，然后将其添加到X坐标，并从Y坐标中减去它:

from turtle import Screen, Turtle  # import turtle module
def draw_square(t, center_x, center_y, side_length):
"""
Function draw_square draws a square
Parameters:
t = reference to turtle
center_x = x coordinate of the center of square
center_y = y coordinate of the center of square
side_length = the length of each side
Returns:
None
"""
offset = side_length/2
t.penup()  # picks up pen of turtle
t.goto(center_x, center_y)  # tell turtle to go to center of drawing
t.dot()  # visualize center of square (for debugging)
t.goto(center_x + offset, center_y - offset)  # adjust for drawing from corner
t.pendown()  # put pen down
for _ in range(4):  # create loop to repeat 4 times
t.left(90)  # turn left 90 degrees
t.forward(side_length)  # move forward the length given
def main():  # define main function
t = Turtle()  # attach turtle to t
draw_square(t, 100, 100, 75)  # use the values to make a square
screen = Screen()
main()  # call function
screen.exitonclick()