如何使中心点成为我方的中心？

Question

如何使中心点成为我方格的中心？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，不涉及正弦或割线。只需计算一半的side_length，然后将其添加到 X 坐标，然后从 Y 坐标中减去：

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()