# tk_cloth_sim.py

# tk_cloth_sim.py ZZZ

import tkinter as tk
from random import uniform

cloth_width = 18
cloth_height = 12
cloth_spacing = 30
cloth_damping = 0.98
gravity = 0.1
wind = 0.7

ww, hh = 600, 600
root = tk.Tk()
canvas = tk.Canvas(root, width=ww, height=hh)
canvas.pack()

points = []
constraints = []
for y in range(cloth_height + 1):
    for x in range(cloth_width + 1):
        point = {
            'x': x * cloth_spacing,
            'y': y * cloth_spacing + 20,
            'old_x': x * cloth_spacing,
            'old_y': y * cloth_spacing,
            'pinned': (x == 0 and y == 0) or (x == cloth_width and y == 0),
        }
        points.append(point)

    for x in range(cloth_width):
        a = y * (cloth_width + 1) + x
        b = a + 1
        constraints.append({
            'point_a': points[a],
            'point_b': points[b],
            'length': cloth_spacing,
        })

for y in range(cloth_height):
    for x in range(cloth_width + 1):
        a = y * (cloth_width + 1) + x
        b = a + cloth_width + 1
        constraints.append({
            'point_a': points[a],
            'point_b': points[b],
            'length': cloth_spacing,
        })

points[cloth_width]['x'] = ww
points[cloth_width]['pinned'] = True

drag_point = None

def on_mouse_down(event):
    global drag_point
    for point in points:
        if abs(point['x'] - event.x) < cloth_spacing:
            if abs(point['y'] - event.y) < cloth_spacing:
                drag_point = point
                drag_point['xm'] = event.x
                drag_point['ym'] = event.y
                return

def on_mouse_move(event):
    if drag_point:
        drag_point['x'] = drag_point['xm'] = event.x
        drag_point['y'] = drag_point['ym'] = event.y

def on_mouse_up(event):
    global drag_point
    drag_point = None

canvas.bind('<ButtonPress-1>', on_mouse_down)
canvas.bind('<B1-Motion>', on_mouse_move)
canvas.bind('<ButtonRelease-1>', on_mouse_up)

while True:
    for point in points:
        if not point['pinned']:
            velocity_x = (point['x'] - point['old_x']) * cloth_damping
            velocity_y = (point['y'] - point['old_y']) * cloth_damping
            point['old_x'] = point['x']
            point['old_y'] = point['y']
            point['x'] += velocity_x + uniform(-wind, wind)
            point['y'] += velocity_y + gravity + uniform(-wind, wind)

    for constraint in constraints:
        point_a = constraint['point_a']
        point_b = constraint['point_b']
        length = constraint['length']
        dx = point_b['x'] - point_a['x']
        dy = point_b['y'] - point_a['y']
        distance = (dx ** 2 + dy ** 2) ** 0.5
        difference = length - distance
        percentage = difference / distance / 2
        offset_x = dx * percentage
        offset_y = dy * percentage
        if not point_a['pinned']:
            point_a['x'] -= offset_x
            point_a['y'] -= offset_y
        if not point_b['pinned']:
            point_b['x'] += offset_x
            point_b['y'] += offset_y

    if drag_point:
        drag_point['x'] = drag_point['xm']
        drag_point['y'] = drag_point['ym']

    canvas.delete('cloth')

    for y in range(cloth_height + 1):
        point_coords = [(points[y * (cloth_width + 1) + x]['x'], points[y * (cloth_width + 1) + x]['y']) for x in range(cloth_width + 1)]
        canvas.create_line(point_coords, tags='cloth', fill='black')

    for x in range(cloth_width + 1):
        point_coords = [(points[y * (cloth_width + 1) + x]['x'], points[y * (cloth_width + 1) + x]['y']) for y in range(cloth_height + 1)]
        canvas.create_line(point_coords, tags='cloth', fill='black')

    root.update()

root.mainloop()