In this article, we will draw an elliptical orbit at its center in Python using the Pygame module. We will draw two more circles on an elliptical orbit and move them in orbit. This is similar to the earth revolving around the sun but the only difference is that here 2 circles(planets) move in the same orbit ensuring that they will not collapse. The circle at the center can be considered as the sun and the circles in orbit can be considered as earth and artificial earth.
To install Pygame we will use pip. Open the terminal and type the following command:
pip install pygame
Python program to simulate elliptical orbits in Pygame
Step 1: Import Pygame and initialize it.
Python3
import pygame
import math
# initialize the pygamepygame.init() |
Step 2: Define the width and height of the window and create a game window.
Python3
# define width of screenwidth = 1000
# define height of screenheight = 600
screen_res = (width, height)
pygame.display.set_caption("GFG Elliptical orbit")
screen = pygame.display.set_mode(screen_res)
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Step 3: Define colors in RGB format. We will use these colors in our game.
Python3
# define colors in RGB format# These colors will be used in our gamered = (255, 0, 0)
green = (0, 255, 0)
blue = (0, 0, 255)
cyan = (0, 255, 255)
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Step 4: Define the center of the screen, the radius of the ellipse, and the clock. This center will be used to draw a circle at the center which represents Sun. And the radius of the ellipse will be used to calculate the position of the planet with time.
Python3
# centers of screenX_center = width//2
Y_center = height//2
# radius of ellipse# X_ellipse is major radius of ellipsisX_ellipse = 400
# Y_ellipse is minor radius of ellipsisY_ellipse = 225
# pygame.time.Clock() will be used further # in the game loop to control the speed of the planet.clock = pygame.time.Clock()
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Step 5: Defining the code inside the game loop
- Firstly we create a loop to rotate our planet. We need to update the position of our planets with time, so for this, we need a loop to cover 360 degrees.
- Then we create an event loop, to get events from the queue.
- Then we check if a user wants to exit the game or not. Also, we fill black color on the screen.
- Now we find the coordinates of our planets, for this we will use the major and minor radius of the ellipse.
- Draw a circle or sun at the center of the screen, and draw an ellipse on the screen.
- Now we need to draw our planets for that we will use previously calculated x and y coordinates to draw planets.
- In last we will update our screen.
Python3
while True:
for degree in range(0,360,1):
# event loop
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
# fill black color on screen
screen.fill([0,0,0])
# We will find coordinates of 2 planet that
# will rotate in same ellipse
# calculate coordinates of planet 1
# x_planet is x coordinate
x_planet_1 = int(math.cos
(degree * 2 * math.pi/360)
* X_ellipse) + X_center
# y_planet is y coordinate
y_planet_1 = int(math.sin(degree * 2 *
math.pi/360) *
Y_ellipse) + Y_center
# calculate coordinates of planet 2
# As we want our planets to be opposite to
# each other so we will maintain a difference of
# 180 degrees between then
degree_2 = degree+180
# degree will be always between 0 and 360
if degree>180:
degree_2 = degree-180
# x_planet is x coordinate
x_planet_2 = int(math.cos(degree_2 * 2 *
math.pi/360) *
X_ellipse) + X_center
# y_planet is y coordinate
y_planet_2 = int(math.sin(degree_2 *
2 * math.pi/360)
* Y_ellipse) + Y_center
# draw circle in center of screen
pygame.draw.circle(surface=screen,
color=red,
center=[X_center,Y_center],
radius=60)
# draw ellipse
# Coordinate of left topmost point is (100,75)
# width of ellipse = 2*(major radius of ellipse)
# height of ellipse = 2*(minor radius of ellipse)
pygame.draw.ellipse(surface=screen,
color=green,
rect=[100,75,800,450],
width=1)
# draw both planets
# x_planet_1, y_planet_1, x_planet_2 and
# y_planet_2 are calculated above
pygame.draw.circle(surface=screen,
color=blue,
center=[x_planet_1,y_planet_1],
radius=40)
pygame.draw.circle(surface=screen,
color=cyan,
center=[x_planet_2,y_planet_2],
radius=40)
# Frame Per Second /Refresh Rate
clock.tick(5)
# update screen
pygame.display.flip()
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Below is the complete code:
Python3
import pygame
import math
# initialize the pygamepygame.init()# define width of screenwidth = 1000
# define height of screenheight = 600
screen_res = (width, height)
pygame.display.set_caption("GFG Elliptical orbit")
screen = pygame.display.set_mode(screen_res)
# define colors in RGB format# These colors will be used in our gamered = (255, 0, 0)
green = (0, 255, 0)
blue = (0, 0, 255)
cyan = (0, 255, 255)
# centers of screenX_center = width//2
Y_center = height//2
# radius of ellipse# X_ellipse is major radius of ellipsisX_ellipse = 400
# Y_ellipse is minor radius of ellipsisY_ellipse = 225
# pygame.time.Clock() will be used further# in the game loop to control# the speed of the planet.clock = pygame.time.Clock()
while True:
for degree in range(0, 360, 1):
# event loop
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
# fill black color on screen
screen.fill([0, 0, 0])
# We will find coordinates of 2 planet
# that will rotate in same ellipse
# calculate coordinates of planet 1
# x_planet is x coordinate
x_planet_1 = int(math.cos(degree * 2 * math.pi/360)
* X_ellipse) + X_center
# y_planet is y coordinate
y_planet_1 = int(math.sin(degree * 2 * math.pi/360)
* Y_ellipse) + Y_center
# calculate coordinates of planet 2
# As we want our planets to be opposite to
# each other so we will maintain a difference
# of 180 degrees between then
degree_2 = degree+180
# degree will be always between 0 and 360
if degree > 180:
degree_2 = degree-180
# x_planet is x coordinate
x_planet_2 = int(math.cos(degree_2 * 2 * math.pi/360)
* X_ellipse) + X_center
# y_planet is y coordinate
y_planet_2 = int(math.sin(degree_2 * 2 * math.pi/360)
* Y_ellipse) + Y_center
# draw circle in center of screen
pygame.draw.circle(surface=screen, color=red, center=[
X_center, Y_center], radius=60)
# draw ellipse
# Coordinate of left topmost point is (100,75)
# width of ellipse = 2*(major radius of ellipse)
# height of ellipse = 2*(minor radius of ellipse)
pygame.draw.ellipse(surface=screen, color=green,
rect=[100, 75, 800, 450], width=1)
# draw both planets
# x_planet_1, y_planet_1, x_planet_2
# and y_planet_2 are calculated above
pygame.draw.circle(surface=screen, color=blue, center=[
x_planet_1, y_planet_1], radius=40)
pygame.draw.circle(surface=screen, color=cyan, center=[
x_planet_2, y_planet_2], radius=40)
# Frame Per Second /Refresh Rate
clock.tick(5)
# update screen
pygame.display.flip()
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Output:
GIF OUTPUT