#!/usr/bin/env python

#------------------------------------------------------------------------------
# particelle2.py - by C.Fin - Python2&3
#------------------------------------------------------------------------------

try: import tkinter as tk
except ImportError: import Tkinter as tk
from random import randint
from math import hypot

#------------------------------------------------------------------------------

WID = HEI = 500        # dimensioni canvas
N_PARTICELLE = 40      # numero di particelle
F_PARTICELLE = 500.0   # forza respingente tra particelle
RAGGIO       = 5       # raggio particelle
SMORZAMENTO  = 0.99    # fattore smorzamento del moto

#------------------------------------------------------------------------------

class Particella:

    def __init__ (self, item):
        area = int(0.3 * WID)
        self.x = randint(-area, area) + WID/2.0
        self.y = randint(-area, area) + HEI/2.0
        self.vx = randint(-1, 1)
        self.vy = randint(-1, 1)
        self.item = item

#------------------------------------------------------------------------------

def calcola_particelle(forzac, part):

    #------calcola contributo campo esterno
    
    for p in part:
        dx = p.x - WID/2
        dy = HEI/2 - p.y
        dist = hypot(dx, dy)
        distc = WID/2 - dist
        forza= -forzac / (distc * distc) * 360
        forzax = forza * dx / dist        
        forzay = -forza * dy / dist        
        p.vx += forzax
        p.vy += forzay

    #------calcola contributo altre particelle

    if len(part) > 1:
        for i in range(len(part)):
            for j in range(len(part)):
                if j != i:
                    dx = part[i].x - part[j].x
                    dy = part[i].y - part[j].y
                    dist = hypot(dx, dy)
                    if dist < 12: dist = 12 # limita forza repulsiva
                    forza = -F_PARTICELLE / (dist * dist)
                    forzax = -forza * dx / dist        
                    forzay = -forza * dy / dist        
                    part[i].vx += forzax
                    part[i].vy += forzay

    #------aggiorna posizioni        

    for p in part:
        p.vx *= SMORZAMENTO
        p.vy *= SMORZAMENTO
        p.x += p.vx
        p.y += p.vy

#------------------------------------------------------------------------------

def disegna_particelle(canvas, part):
    for p in part:
        canvas.coords(p.item, p.x-RAGGIO, p.y-RAGGIO, p.x+RAGGIO, p.y+RAGGIO)
       
#------------------------------------------------------------------------------

class GUI:

    def __init__(self):
        self.form = tk.Tk()       
        self.form.title("Particelle")       
        self.form.resizable(False, False)

        self.frame1 = tk.Frame(self.form, width=100, relief="raised", bd=2)
        self.frame1.pack(side="left", expand=1, fill="y")

        self.canvas = tk.Canvas(
            self.form, highlightthickness=0,
            width=WID, height=HEI, bg="white",)
        self.canvas.pack(side="left", expand=1, fill="both")

        self.scale1 = tk.Scale(self.frame1, from_=100, to=10)    
        self.scale1.pack(expand=1, padx=8)

        self.campo1 = self.canvas.create_oval(
            (10, 10, WID-10, HEI-10), outline="red", width=0)

#------------------------------------------------------------------------------

class Particelle:
   
    def __init__ (self):
        self.f_campo = 1.0
        self.gui = GUI()
        self.gui.scale1.configure(command=self.chgscale)
        self.p = []
        for _ in range(N_PARTICELLE):
            item = self.gui.canvas.create_oval(
                (0, 0, 0, 0), fill="green", outline="black")
            self.p.append(Particella(item))


    def chgscale(self, valore):
        self.f_campo = float(valore)
        self.gui.canvas.itemconfig(
            self.gui.campo1, width=int(self.f_campo)/10)


    def animazione(self):
        self.gui.form.after(30, self.animazione)
        calcola_particelle(self.f_campo, self.p)
        disegna_particelle(self.gui.canvas, self.p)


    def start(self):
        self.animazione()
        self.gui.form.mainloop() 

#------------------------------------------------------------------------------

app = Particelle() 
app.start()