Drawing a line between points in pygame

Admin 1
Viewed 236

So I was trying to make something that resembles fireworks. I made a particle class, which will make up the fireworks.

  class Particle:
        def __init__(self, pos, angle):
            self.pos = pos
            self.angle = angle
            self.color = choice([(217, 103, 51), (238, 95, 30)])
            self.radius = uniform(2, 7)
            self.pull = 0
            self.start = time.time()
    
        def adjust(self):
            self.radius -= 0.03
    
        def draw(self):
            if self.radius > 0:
                pygame.draw.circle(D, self.color, (int(self.pos[0])
                                               , int(self.pos[1])), int(self.radius))
    
        def move(self):
            now  = time.time()
            self.pos[0] += cos(radians(self.angle)) * 2
            self.pos[1] += (sin(radians(self.angle)) + self.pull) * 2
            if now - self.start > 0.1:
                self.pull += 0.25
                self.start = now

Then I made a Fireworks class which shoots particles from 0 to 360 degrees.

class FireWorks:
    def __init__(self):
        self.particles = []
        for i in range(360):
            self.particles.append(Particle([600, 300], i))

    def explode(self):
        for i in range(len(self.particles)):
            self.particles[i].draw()
            self.particles[i].move()
            self.particles[i].adjust()
        for p in self.particles:
            if p.radius < 0:
                self.particles.remove(p)

Now I want to draw a line from the position they spawn (600, 300), along the path the particles take. But the thing is particles don't move in a straight line. To make it look a bit more natural, I did this to the y-value: self.pos[1] += (sin(radians(self.angle)) + self.pull) * 2. Value of self.pull is incremented by 0.25 every 0.1 seconds. One thing I tried is to store the position value every time y increases and draw lines between those positions so that a curve forms, but nothing is drawn at all and it causes a lag. Here is the code showing just the bits involved in generating the points and drawing lines between the points.

class Particle:
    def __init__(self, pos, angle):
        self.points = [] #added list to init to hold the points between which lines need  to be drawn

    def move(self):
       # In move method, every time a value is added to y, we record position at that point
       if now - self.start > 0.1:
          self.points.append(self.pos)
          self.pull += 0.25
    
    def draw(self):
        # Iterate through the points in the list and draw a line between them
        for i in range(len(self.points)):
            for j in range(1, len(self.points)):
                pygame.draw.line(D, self.color, (int(self.points[i][0]), int(self.points[i][1]))
                                 , (int(self.points[j][0]), int(self.points[j][1])), int(self.radius))

Here is the complete code for reference.

import pygame
from math import radians, sin, cos
from random import choice, uniform, randint
import time

pygame.init()

WIN = pygame.display
D = WIN.set_mode((1200, 600))

class Particle:
    def __init__(self, pos, angle):
        self.pos = pos
        self.angle = angle
        self.color = choice([(217, 103, 51), (238, 95, 30)])
        self.radius = uniform(2, 7)
        self.pull = 0
        self.start = time.time()
        self.points = []

    def adjust(self):
        self.radius -= 0.03

    def draw(self):
        if self.radius > 0:
            pygame.draw.circle(D, self.color, (int(self.pos[0])
                                           , int(self.pos[1])), int(self.radius))
            for i in range(len(self.points)):
                for j in range(1, len(self.points)):
                    pygame.draw.line(D, self.color, (int(self.points[i][0]), int(self.points[i][1]))
                                     , (int(self.points[j][0]), int(self.points[j][1])), int(self.radius))

    def move(self):
        now  = time.time()
        self.pos[0] += cos(radians(self.angle)) * 2
        self.pos[1] += (sin(radians(self.angle)) + self.pull) * 2
        if now - self.start > 0.1:
            self.points.append(self.pos)
            self.pull += 0.25
            self.start = now


class FireWorks:
    def __init__(self):
        self.particles = []
        for i in range(360):
            self.particles.append(Particle([600, 300], i))

    def explode(self):
        for i in range(len(self.particles)):
            self.particles[i].draw()
            self.particles[i].move()
            self.particles[i].adjust()
        for p in self.particles:
            if p.radius < 0:
                self.particles.remove(p)
            

f = FireWorks()
D.fill((0, 0, 0))
while True:
    pygame.event.get()
    D.fill((0, 0, 0))
    f.explode()
    WIN.flip()
render pygame python
1 Answers

You have to append a copy of the position tuple to the list of positions, rather than an reference to the positions:

self.points.append(self.pos)

self.points.append(self.pos[:])

Note, self.pos refers to a tuple with 2 components. Hence self.points.append(self.pos) appends a new reference to this position to the list, but it doesn't generate a new position.

To improve the performance, I recommend to add integral positions to the list and to draw the line along the path of the particles by pygame.draw.lines():

class Particle:
    # [...]

    def draw(self):
        if self.radius > 0:
            pygame.draw.circle(D, self.color, (int(self.pos[0])
                                           , int(self.pos[1])), int(self.radius))
            if len(self.points) > 1:
                pygame.draw.lines(D, self.color, False, self.points)

    def move(self):
        now  = time.time()
        self.pos[0] += cos(radians(self.angle)) * 2
        self.pos[1] += (sin(radians(self.angle)) + self.pull) * 2
        if now - self.start > 0.1:
            x, y = round(self.pos[0]), round(self.pos[1])
            self.points.append((x, y))
            self.pull += 0.25
            self.start = now
user_55777650
Related