Pygame - Gravity Methods - python

I'm in the process of making a simple game in pygame. Its looking to be a platformer RPG. But that is neither final or relevant per this question. So far i have very little functionality in the game. Its just a skeleton at this point if that. My question is kind of two fold:
Whats the best (in terms of performance and flexibility) way to add gravity to classes in pygame?
What are the best practices for adding gravity in general? For example, do you just simply do a "if keyPressed == k_W then subtract 2pixels per tick from player-y for 20 ticks" or something with velocity in the up or negative-y direction?
I've seen other posts on adding gravity to games after the fact, where adding it really wasn't thought about during initial development. I want to add it in as early as possible so instead of adding gravity to other things, i can add other things to gravity. I'm going to continue to read up on this, so if you prefer to point me in the direction of some online resources, I'd much appreciate that as well!

Quick dislaimer: I do not know multiple ways to incorporate gravity, so I can not say which is "best". But, if you're fighting the performance battle in Python, you've probably fighting the wrong battle.
For gravity, you can use a vector system. Say a character jumps off the ground and has initial velocity of [5, -15] (negative y because positive y is down!), you can move your character's rect by this velocity every frame to simulate movement. To throw gravity into this, you need to add 9.8 to your y velocity component value every second. So 1 second in, the velocity will be about [5, -5]. This will have your character slow to a stop, and begin moving down.
For key pressed movement, I recommend using booleans. An example, upon pressing k_U , a variable that says you are moving up becomes True. Then, if this variable is True, you move him, say, [0, -5]. Upon keyup, set variable to false. Do this for north/east/south/west, and then you have a movement system in 4 directions, that moves you while you hold the key down.

I used the 1/2 mg^2 equation in this code, which has a snow like effect:
import math, sys, random, time
import pygame, inputbox
from pygame.locals import *
class flake:
def __init__(self, xpos, ypos, mass, color, drift):
self.xpos = xpos
self.ypos = ypos
self.mass = mass
self.rect = pygame.Rect(xpos, ypos, 2, 2)
self.checked = False
self.color = color
self.drift = drift
size = width, height = 510, 700
BLACK = (0,0,0)
WHITE = (255, 255, 255)
GREY = (128,128,128)
DARKGREY = (169,169,169)
SILVER = (192,192,192)
LIGHTGREY = (211,211,211)
LIGHTESTGREY = (220,220,220)
pygame.init()
screen = pygame.display.set_mode(size)
background = pygame.Surface(screen.get_size())
background = background.convert()
background.fill(BLACK)
def init():
global theSnow, snowColours, clock, startrange
theSnow = []
snowColours = []
snowColours.append(WHITE)
snowColours.append(GREY)
snowColours.append(DARKGREY)
snowColours.append(SILVER)
snowColours.append(LIGHTGREY)
snowColours.append(LIGHTESTGREY)
for c in range(2000):
mass = 0.0
mass = float(random.randint(1,8) / 100.0)
xpos = random.randint(0,width)
ypos = random.randint(0,5)
ypos = -ypos
drift = ypos/10.0
colour = snowColours[random.randint(0,5)]
f = flake(xpos, ypos, mass, colour, drift)
theSnow.append(f)
print "flake x = " + str(f.xpos) + " y = " + str(f.ypos) + " mass = " + str(f.mass)
startrange = 200
clock = pygame.time.Clock()
def run():
global theSnow, clock
global startrange
newrange = 0
while True:
events = pygame.event.get()
for event in events:
if event.type == pygame.QUIT:
sys.exit()
keys=pygame.key.get_pressed()
if keys[K_q]:
return
g = 3
for count in range(startrange):
yinc = 0.0
yuncertainty = float(random.randint(1,5)/10.0)
yinc = float(0.5 * theSnow[count].mass * (g*g)) + yuncertainty
theSnow[count].ypos += yinc
xuncertainty = random.randint(1,10)
if xuncertainty > 4:
theSnow[count].xpos += theSnow[count].drift
else:
theSnow[count].xpos -= theSnow[count].drift
theSnow[count].rect = pygame.Rect(theSnow[count].xpos, theSnow[count].ypos, 2,2)
if not theSnow[count].checked:
if theSnow[count].ypos > 30:
for c in range(newrange, startrange):
print " c= " + str(c)
theSnow[c].checked = True
if startrange < 2000:
startrange += 100
newrange = startrange - 100
print " newrange = " + str(newrange)
print " startrange = " + str(startrange)
update()
pygame.time.wait(10)
#clock.tick(10)
def update():
global theSnow, startrange
background.fill(BLACK)
for count in range(startrange):
pygame.draw.rect(background, theSnow[count].color, theSnow[count].rect)
screen.blit(background, (0, 0))
pygame.display.flip()
if __name__ == "__main__":
init()
run()

Related

My screen glitches out when I try to run my subprogram code

I'm working on a subprogram code that will make this happy face bounce around the screen and turn different colours. For some reason, the screen turns into that black glitchy screen and when I press exit at the top the face shows for a quick second before the program shuts down. I can't figure out why this is, here is my code and I've included a picture of what happens at first when I run it:
""" Program to show a very basic function
Most of the program is exactly the same as other programs we have done
The main difference is the grouping of code into a function called
drawHappy() to draw a few shapes together
In the main loop we "call" this function whenever we want to draw this
group of shapes
"""
# import the necessary modules
import pygame
import sys
import math
import random
from random import randint
# initialize pygame
pygame.init()
# set the size for the surface (screen)
# note this screen is resizable by the user
screen = pygame.display.set_mode((800, 600), pygame.RESIZABLE)
# set the caption for the screen
pygame.display.set_caption("Happy Face")
#screen width and height
screenW = screen.get_width()
screenH = screen.get_height()
# define colours you will be using
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)
BLUE = (0, 0, 255)
BLACK = (0, 0, 0)
YELLOW = (255, 255, 0)
# funtion to draw a the "happy face"
# it has 4 parameters passed to it xPos, yPos, radius, and colour
# notice all the shapes are drawn "relative" to the xPos and yPos and the radius
def drawHappy(xPos,yPos,r,colour):
pygame.draw.circle(screen,colour,(xPos,yPos),r,1)
eyeRadius = int(1/6*r)
eyeX = int(xPos-1/3*r)
eyeY = int(yPos- 1/3*r)
pygame.draw.circle(screen,colour,(eyeX,eyeY),eyeRadius,1)
eyeX = int(xPos + 1/3*r)
pygame.draw.circle(screen,colour,(eyeX,eyeY),eyeRadius,1)
wMouth = 1.5*r
xMouth = xPos - 3/4*r
yMouth = yPos - 3/4*r
pygame.draw.arc(screen,colour,(xMouth,yMouth,wMouth,wMouth),math.pi,2*math.pi,1)
randomR = randint(1,300)
r = randomR
randomX = randint(r, 800-r)
randomY = randint(r, 600-r)
dx = 0
dy = 0
x = 100
y = 100
speed = 3
x2 = randomX
y2 = randomY
dx2 = speed
dy2 = -speed
colour_list = [YELLOW, BLACK, BLUE, RED, GREEN]
randomcolour = random.choice(colour_list)
colour = RED
# set up clock to control frames per second
clock = pygame.time.Clock()
FPS = 120
# set main loop to True so it will run
main = True
# main loop
while main:
for event in pygame.event.get(): # check for any events (i.e key press, mouse click etc.)
if event.type == pygame.QUIT: # check to see if it was "x" at top right of screen
main = False # set the "main" variable to False to exit while loop
clock.tick(FPS)
screen.fill(WHITE)
oldx = x
oldy = y
x += dx
y += dy
if x >= 800-r or x <= 0+r:
x = oldx
if y >= 600-r or y <= 0+r:
y = oldy
x2 += dx2
y2 += dy2
if x >= 800-r or x <= 0+r:
dx2 = -dx2
randomcolour = random.choice(colour_list)
colour = randomcolour
if y2 >= 600-r or y2 <= 0+r:
dy2 = -dy2
randomcolour = random.choice(colour_list)
colour = randomcolour
# "call" the function "drawHappy()" to draw the happy face
# this is where we would normally do a pygame.draw or a screen.blit()
# we are "passing" the function 4 values to use(x,y,radius, colour)
# it will use these to know where to draw the happy face
drawHappy(x2,y2,r,colour)
pygame.display.flip()
# quit pygame and exit the program (i.e. close everything down)
pygame.quit()
sys.exit()
First of all, you need to call your draw function inside the loop. Your current code shows only a glimpse of "drawing" because it gets executed once you exit the main loop.
So, put your drawHappy() inside of main loop:
while main:
for event in pygame.event.get(): # check for any events (i.e key press, mouse click etc.)
if event.type == pygame.QUIT: # check to see if it was "x" at top right of screen
main = False # set the "main" variable to False to exit while loop
drawHappy(x2,y2,r,colour)
pygame.display.update()
clock.tick(FPS)
screen.fill(WHITE)
Now you will get a random size "smiley" on the screen, But now it will move on exit only, for the same reason it wouldn't display earlier. Next thing is to make it bounce (move). For this you'll need some kind of update of the coordinates, just like you did in the last part of your code, except they also need to be updated during the loop, not after it.
I suggest making a Class because then it will be easier to manipulate the object.
Also, I found it easier to separate draw and update_coordinates code into separate functions and them call them from main loop for example.
Hope this helps, and if you need more help, ask.
Here, I made a quick solution using parts of your code, there is plenty room for improvement especially for update_smiley_position() method where you can control how "smiley" moves.
Also, if you need multiple objects, a list should be passed instead of single object.
import pygame as pg
import math
import random
pg.init()
clock = pg.time.Clock()
window = pg.display.set_mode((800, 600), pg.RESIZABLE)
pg.display.set_caption("Happy Face")
SCREEN_W = window.get_width()
SCREEN_H = window.get_height()
class Smiley:
def __init__(self, x, y, r, color):
self.x = x
self.y = y
self.r = r
self.color = color
self.create_smiley()
def create_smiley(self):
self.eye_radius = int(1/6 * self.r)
self.eye_x1 = int(self.x - 1/3 * self.r)
self.eye_x2 = int(self.x + 1/3 *self.r)
self.eye_y = int(self.y - 1/3 *self.r)
self.mouth_width = 1.5 * self.r
self.mouth_x = self.x - self.r * 0.75
self.mouth_y = self.y - self.r * 0.75
def draw_smiley(self, win):
pg.draw.circle(win, self.color, (self.x, self.y), self.r, 1)
pg.draw.circle(win, self.color, (self.eye_x1, self.eye_y), self.eye_radius, 1)
pg.draw.circle(win, self.color, (self.eye_x2, self.eye_y), self.eye_radius, 1)
pg.draw.arc(win, self.color, (self.mouth_x, self.mouth_y, self.mouth_width, self.mouth_width), math.pi, 2*math.pi, 1)
def update_smiley_position(self):
if self.x >= SCREEN_H - self.r or self.x <= 0 + self.r:
self.x = random.randint(100, 400)
else:
self.x += 5
if self.y >= SCREEN_W - self.r or self.y <= 0 + self.r:
self.y = random.randint(100, 400)
else:
self.y -= 5
self.create_smiley()
def draw(win, smiley):
win.fill(pg.Color("white"))
smiley.draw_smiley(win)
smiley.update_smiley_position()
pg.display.update()
def main_loop(win, smiley):
clock.tick(30)
for event in pg.event.get():
if event.type == pg.QUIT:
return False
draw(win, smiley)
return True
r = random.randint(1, 300)
x = random.randint(r, SCREEN_W - r)
y = random.randint(r, SCREEN_H - r)
smiley = Smiley(x, y, r, pg.Color("red"))
while main_loop(window, smiley):
pass
pg.quit()

Pygame for possible trajectories planning for a car and make the car follow one of that path/trajectory

I have to create a visualization where I have to create a car (I considered to represent it as a rectangle) and develop trajectories for that car depending on its lateral & longitudinal acceleration. My problem is I am unable to create trajectories. I am doing this as a part of own project. Hence I have no idea if I am in the right direction or not. Guide me if I am wrong.
Problem1 : How do I show predicted path trajectories (beginner step to create only 8 trajectories and not many) ? Is a possible way to also create trajectories also like a curve using Pygame? If not, can I use a mix pf pygame and tkinter to create a mix of curved and straight line trajectories?
Problem2 : Make my rectangular car run along the chosen trajectory (curved line or straight line) or make it follow the path defined in trajectory.
Solutions Tried:
I have taken a rectangular sprite as a car with an idea that I can make it move around the desired trajectory. I am successful with sprite creation and moving it. But I am unable to show display any trajectory curve and make the car follow the path. I am not sure if I have to take trajectories also as Sprite or only car as Sprite is sufficient and trajectories as lines/curves?
Code of the above same explanation is as follows:
My Sprite Class :
class Vehicle(pygame.sprite.Sprite):
def __init__(self,x,y,slip_angle,length=4):
super().__init__()
width = 50
height = 50
self.image = pygame.Surface([width,height])
#Create a car
self.image.fill(RED)
self.image.set_colorkey(RED)
pygame.draw.rect(self.image, WHITE, [0, 0, width, height])
self.rect = self.image.get_rect()
#Parameters of car
self.position = position = Vector2(x, y)
self.velocity = Vector2(0.0, 0.0)
self.slip_angle = slip_angle
self.length = length
self.max_velocity = 20
self.brake_deceleration = 10
self.free_deceleration = 2
self.initial_velocity = 0
self.long_acceleration = 0.0
self.lat_acceleration = 0.0
self.acceleration = 0.0
self.steering = 0.0
def update(self,dt):
self.velocity += (self.acceleration * dt, 0)
self.velocity.x = max(-self.max_velocity, min(self.velocity.x, self.max_velocity))
if self.steering:
turning_radius = self.length / sin(radians(self.steering))
angular_velocity = self.velocity.x / turning_radius
else:
angular_velocity = 0
self.position += self.velocity.rotate(-self.angle) * dt
self.slip_angle += degrees(angular_velocity) * dt
Trajectory Class:
class trajectory(object):
def __init__(self,x,y):
self.x = x
self.y = y
def draw():
x_value = []
time = []
for acc in range(10):
for dt in range(0,10,0.05):
x = vehicle1.initial_velocity + (vehicle1.velocity*dt) + (0.5 * vehicle1.long_acceleration * dt* dt)
x_value.append(x)
time.append(dt)
coordinates = (x_value,time)
canvas_1 = Canvas(root,700,600,background='pink')
canvas_1.grid(row=0,column=1)
x1 = coordinates[acc]
y1 = coordinates[time]
canvas_1.create_line(x1,y1)
#pygame.draw.line(screen,GREEN,list(coordinates),(700, 600))
def update(self):
#self.angle = vehicle1.slip_angle*pi / 180
self.velocity_h = vehicle1.velocity*cos(angle)
self.velocity_v = vehicle1.velocity*sin(angle)
Pygame Main Logic :
#main Logic
proceed = True
#Capturing events till exit
while proceed:
for event in pygame.event.get():
if event.type == pygame.QUIT:
proceed = False
vehicle1.update(dt)
sprites_list.update(dt)
screen.fill(WHITE)
#screen.pygame.Surface.fill(color, rect=None, special_flags=0)
pygame.draw.line(screen, BLACK, [0, 0], [700, 300], 5)
# self.screen.blit(rotated, [20,30])
sprites_list.draw(screen)
pygame.display.flip()
clock.tick(60)
pygame.quit()
I thank you for your advices and support. Happy to accept any guidance
A simple re-working of your trajectory.draw() should sort it out. I noticed the initial x and y passed to the constructor don't seem to be used. Is it intended that the trajectory is always from ( 0, 0 ) or suchlike?
def draw( screen, initial_vel, vel, accel ):
coordinates = []
for acc in range(10):
for dt in range( 0, 10, 0.05 ):
x = initial_vel + ( vel * dt ) + ( 0.5 * accel * dt * dt )
coordinates.append( ( x, dt ) )
if ( len( coordinates ) > 1 ):
PINK = ( 255, 192, 203 )
pygame.draw.lines( screen, PINK, False, coordinates )
Pass your Window and Vehicle Velocities as a parameters when calling trajectory.draw(), rather than relying on global variables.
my_trajectory.draw( screen, vehicle1.initial_velocity, vehicle1.velocity, vehicle1.long_acceleration )

Pygame. How to make a rect change direction on collision (boundary check)

Part of an assignment I'm working on is making a ball bounce around the screen, I can make it move, but my boundary test doesn't seem to be working: the ball simply moves in direction instead of changing direction. So to clarify, what I want to ball to do is change direction as it hits the screen edge.
import sys
import pygame
SCREEN_SIZE = 750, 550
BALL_DIAMETER = 16
BALL_RADIUS = BALL_DIAMETER // 2
MAX_BALL_X = SCREEN_SIZE[0] - BALL_DIAMETER
MAX_BALL_Y = SCREEN_SIZE[1] - BALL_DIAMETER
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
LEFT = 11
RIGHT = 12
pygame.init()
clock = pygame.time.Clock()
pygame.display.init()
font = pygame.font.SysFont("impact", 20)
pygame.display.set_caption("Breakout")
screen = pygame.display.set_mode(SCREEN_SIZE)
class Ball:
def __init__(self):
''' '''
self.ball = pygame.Rect(300, 730 -
BALL_DIAMETER,
BALL_DIAMETER, BALL_DIAMETER)
# Draw ball
def draw_ball(self):
pygame.draw.circle(screen,
WHITE, (self.ball.left
+ BALL_RADIUS, self.ball.top +
BALL_RADIUS), BALL_RADIUS)
# Updates the coordinates by adding the speed components
def move_ball(self, x, y):
self.xspeed = x
self.yspeed = y
self.ball = self.ball.move(self.xspeed, self.yspeed)
# bounds check
if self.ball.left <= 0:
self.ball.left = 0
self.xspeed = -self.xspeed
elif self.ball.left >= MAX_BALL_X:
self.ball.left = MAX_BALL_X
self.xspeed = -self.xspeed
if self.ball.top < 0:
self.ball.top = 0
self.yspeed = -self.yspeed
elif self.ball.top >= MAX_BALL_Y:
self.ball.top = MAX_BALL_Y
self.yspeed = -self.yspeed
# shows a message on screen, for testing purposes
class Text:
def show_message(self, message):
self.font = pygame.font.SysFont("impact", 20)
font = self.font.render(message,False, WHITE)
screen.blit(font, (200, 400))
class Game:
def __init__(self):
''' '''
def run(self):
b = Ball()
while 1:
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()
keys = pygame.key.get_pressed()
# fps lock, screen fill and method call for input
clock.tick(60)
screen.fill(BLACK)
b.draw_ball()
b.move_ball(5, -5)
# used to keep track of various elements
# Text().show_message("P: " + str(p))
pygame.display.flip()
# Creates instance of the game class, and runs it
if __name__ == "__main__":
Game().run()
Your only call to move_ball uses a constant vector.
Since you never change the call parameters, the ball moves only that way.
b.move_ball(5, -5)
Yes, you change the vector components within move_ball when you hit a wall. However, on the next call, you change them back to the original values and move the ball in the original direction.
You have to initialize the vector outside move_ball, and then let the routine access the existing vector when it's called.

Python Pygame randomly draw non overlapping circles

Im very new to python and seem to be missing something.
I want to randomly draw circles on a pygame display but only if the circles don't overlap each other.
I believe I must find the distance between all circle centers and only draw it if the distance is bigger than circle radius * 2.
I've tried many different things but all without success, I always get the same result - circles drawn overlapping.
#!/usr/bin/env python
import pygame, random, math
red = (255, 0, 0)
width = 800
height = 600
circle_num = 10
tick = 2
speed = 5
pygame.init()
screen = pygame.display.set_mode((width, height))
class circle():
def __init__(self):
self.x = random.randint(0,width)
self.y = random.randint(0,height)
self.r = 100
def new(self):
pygame.draw.circle(screen, red, (self.x,self.y), self.r, tick)
c = []
for i in range(circle_num):
c.append('c'+str(i))
c[i] = circle()
for j in range(len(c)):
dist = int(math.hypot(c[i].x - c[j].x, c[i].y - c[j].y))
if dist > int(c[i].r*2 + c[j].r*2):
c[j].new()
pygame.display.update()
else:
continue
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
quit()
You did not check against all other circles. I added a variable shouldprint which gets set to false if any other circle is too close.
import pygame, random, math
red = (255, 0, 0)
width = 800
height = 600
circle_num = 20
tick = 2
speed = 5
pygame.init()
screen = pygame.display.set_mode((width, height))
class circle():
def __init__(self):
self.x = random.randint(0,width)
self.y = random.randint(0,height)
self.r = 100
def new(self):
pygame.draw.circle(screen, red, (self.x,self.y), self.r, tick)
c = []
for i in range(circle_num):
c.append('c'+str(i))
c[i] = circle()
shouldprint = True
for j in range(len(c)):
if i != j:
dist = int(math.hypot(c[i].x - c[j].x, c[i].y - c[j].y))
if dist < int(c[i].r*2):
shouldprint = False
if shouldprint:
c[i].new()
pygame.display.update()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
quit()
The for loop has been changed to a while loop. It will keep trying to generate circles until the target number is reached. A circle is first generated. Then, it checks if it intersects with any existing circle using the formula from this answer.
It iterates through every existing circle (store in the list circles) and performs the check using the formula. any() returns True if the formula evaluates to True for any iteration. If it's True, it means it found an intersection. Thus, it continues to the next iteration to try again with a new circle.
circles = []
while len(circles) < circle_num:
new = circle()
if any(pow(c.r - new.r, 2) <=
pow(c.x - new.x, 2) + pow(c.y - new.y, 2) <=
pow(c.r + new.r, 2)
for c in circles):
continue
circles.append(new)
new.new()
pygame.display.update()

Adding gravity to a bouncing ball using vectors

I have a gravity vector (in the form [r, theta]) which I add to my ball's velocity vector. For some reason, the ball doesn't return to the same height after bouncing, but instead slowly loses height sporadically. I am guessing there's some rounding error or something in a calculation I'm using, but I can't isolate the issue.
Here is my code. You need both files and pygame to run it. Sorry if it's a little confusing. I can comment anything some more if you want.
I added a marker whenever the ball reaches its max height so you guys what I mean. I want the ball to return to exactly the same height every time it bounces.
I took a little bit of unnecessary code out. The full program is under the pastebin links.
https://pastebin.com/FyejMCmg - PhysicsSim
import pygame, sys, math, tools, random, time
from pygame.locals import *
clock = pygame.time.Clock()
lines = []
class Particle:
def __init__(self,screen,colour, mass, loc, vel):
self.screen = screen
self.colour = colour
self.mass = mass
self.x = loc[0]
self.y = loc[1]
self.location = self.x,self.y
self.speed = vel[0]
self.angle = vel[1]
def update(self):
global lines
# add gravity
self.speed,self.angle = tools.add_vectors2([self.speed,self.angle], tools.GRAVITY)
# update position
dt = clock.tick(60)
self.x += self.speed * tools.SCALE * math.cos(self.angle) * dt
self.y -= self.speed * tools.SCALE * math.sin(self.angle) * dt
self.location = int(self.x),int(self.y)
# border checking
do = False
n=[]
if ((self.y+self.mass) > tools.SCREEN_HEIGHT):
self.y = tools.SCREEN_HEIGHT-self.mass
n = [0,1]
do = True
# adds position to array so max height so max height can be recorded
if (self.speed==0):
lines.append([self.screen, self.location, self.mass])
# bounce
if do:
#init, convert everything to cartesian
v = tools.polarToCartesian([self.speed, self.angle])
#final -> initial minus twice the projection onto n, where n is the normal to the surface
a = tools.scalarP(2*abs(tools.dotP(v,n)),n) #vector to be added to v
v = tools.add_vectors(v,a)
self.angle = tools.cartesianToPolar(v)[1] # does not set magnitude
# drawing
pygame.draw.circle(self.screen, self.colour, self.location, self.mass, 0)
# draws max height line
def draw_line(l):
screen = l[0]
location = l[1]
radius = l[2]
pygame.draw.line(screen, tools.BLACK, [location[0] + 15, location[1]-radius],[location[0] - 15, location[1]-radius])
def main():
pygame.init()
DISPLAY = pygame.display.set_mode(tools.SCREEN_SIZE,0,32)
DISPLAY.fill(tools.WHITE)
particles = []
particles.append(Particle(DISPLAY, tools.GREEN, 10, [100,100], [0,0]))
done = False
while not done:
global lines
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
DISPLAY.fill(tools.WHITE)
for i in particles:
i.update()
for l in lines:
draw_line(l)
pygame.display.update()
main()
https://pastebin.com/Epgqka31 - tools
import math
#colours
WHITE = (255, 255, 255)
BLUE = ( 0, 0, 255)
GREEN = ( 0, 255, 0)
RED = ( 255, 0, 0)
BLACK = ( 0, 0, 0)
COLOURS = [WHITE,BLUE,GREEN,RED,BLACK]
#screen
SCREEN_SIZE = SCREEN_WIDTH,SCREEN_HEIGHT = 1000,700
#vectors
GRAVITY = [5.0, 3*math.pi/2] # not 9.8 because it seems too high
SCALE = 0.01
# converts polar coordinates to cartesian coordinates in R2
def polarToCartesian(v):
return [v[0]*math.cos(v[1]), v[0]*math.sin(v[1])]
# converts cartesian coordinates to polar coordinates in R2
def cartesianToPolar(v):
return [math.sqrt(v[0]**2 + v[1]**2), math.atan2(v[1],v[0])]
# dots two cartesian vectors in R2
def dotP(v1, v2):
return v1[0]*v2[0] + v1[1]*v2[1]
# multiplies cartesian vector v by scalar s in Rn
def scalarP(s,v):
v_=[]
for i in v:
v_.append(s*i)
return v_
# returns the sum of two cartesian vectors in R2
def add_vectors(v1, v2):
return [v1[0]+v2[0], v1[1]+v2[1]]
# returns the sum of two polar vectors in R2, equations from https://math.stackexchange.com/questions/1365622/adding-two-polar-vectors
def add_vectors2(v1,v2):
r1,r2,t1,t2 = v1[0],v2[0],v1[1],v2[1]
return [math.sqrt(r1**2 + r2**2 + 2*r1*r2*math.cos(t2-t1)), t1 + math.atan2(r2*math.sin(t2 - t1), r1 + r2*math.cos(t2 - t1))]
Your time interval, dt = clock.tick(60), is not a constant. If you change it to dt = 60 your program runs as expected.
Have a look a the Verlet Algorithm and implement it in your code. You are on the right track!

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