import pygame import random import math background_colour = (255,255,255) (width, height) = (400, 400) drag = 0.999 elasticity = 0.75 gravity = (math.pi, 0.002) def addVectors((angle1, length1), (angle2, length2)): x = math.sin(angle1) * length1 + math.sin(angle2) * length2 y = math.cos(angle1) * length1 + math.cos(angle2) * length2 angle = 0.5 * math.pi - math.atan2(y, x) length = math.hypot(x, y) return (angle, length) def findParticle(particles, x, y): for p in particles: if math.hypot(p.x-x, p.y-y) <= p.size: return p return None def collide(p1, p2): dx = p1.x - p2.x dy = p1.y - p2.y dist = math.hypot(dx, dy) if dist < p1.size + p2.size: tangent = math.atan2(dy, dx) angle = 0.5 * math.pi + tangent angle1 = 2*tangent - p1.angle angle2 = 2*tangent - p2.angle speed1 = p2.speed*elasticity speed2 = p1.speed*elasticity (p1.angle, p1.speed) = (angle1, speed1) (p2.angle, p2.speed) = (angle2, speed2) p1.x += math.sin(angle) p1.y -= math.cos(angle) p2.x -= math.sin(angle) p2.y += math.cos(angle) class Particle(): def __init__(self, (x, y), size): self.x = x self.y = y self.size = size self.colour = (0, 0, 255) self.thickness = 0 self.speed = 0 self.angle = 0 def display(self): pygame.draw.circle(screen, self.colour, (int(self.x), int(self.y)), self.size, self.thickness) def move(self): (self.angle, self.speed) = addVectors((self.angle, self.speed), gravity) self.x += math.sin(self.angle) * self.speed self.y -= math.cos(self.angle) * self.speed self.speed *= drag def bounce(self): if self.x > width - self.size: self.x = 2*(width - self.size) - self.x self.angle = - self.angle self.speed *= elasticity elif self.x < self.size: self.x = 2*self.size - self.x self.angle = - self.angle self.speed *= elasticity if self.y > height - self.size: self.y = 2*(height - self.size) - self.y self.angle = math.pi - self.angle self.speed *= elasticity elif self.y < self.size: self.y = 2*self.size - self.y self.angle = math.pi - self.angle self.speed *= elasticity screen = pygame.display.set_mode((width, height)) pygame.display.set_caption('Tutorial 8') number_of_particles = 5 my_particles = [] for n in range(number_of_particles): size = random.randint(10, 20) x = random.randint(size, width-size) y = random.randint(size, height-size) particle = Particle((x, y), size) particle.speed = random.random() particle.angle = random.uniform(0, math.pi*2) my_particles.append(particle) selected_particle = None running = True while running: for event in pygame.event.get(): if event.type == pygame.QUIT: running = False elif event.type == pygame.MOUSEBUTTONDOWN: (mouseX, mouseY) = pygame.mouse.get_pos() selected_particle = findParticle(my_particles, mouseX, mouseY) elif event.type == pygame.MOUSEBUTTONUP: selected_particle = None if selected_particle: (mouseX, mouseY) = pygame.mouse.get_pos() dx = mouseX - selected_particle.x dy = mouseY - selected_particle.y selected_particle.angle = 0.5*math.pi + math.atan2(dy, dx) selected_particle.speed = math.hypot(dx, dy) * 0.1 screen.fill(background_colour) for i, particle in enumerate(my_particles): particle.move() particle.bounce() for particle2 in my_particles[i+1:]: collide(particle, particle2) particle.display() pygame.display.flip()