python - Making an object move in an orbit when I have the x and y coordinates

Question

This code is mostly just the generic start up of a pygame window but I'm trying to make it so the object moves (the planet object I've made) in the orbit around the sun object I've made for the coordinates I've given it. I know the x and y values are updating but I don't understand why the object doesn't move.

#import the library
import pygame
import math


#classes

class button:
    def _init_ (self,screen, colour, x, y, width,height, letter):
        self.screen = screen
        self.colour = colour
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.letter = letter
        self.radius = radius
    def draw(self):
        pygame.draw.rect(self.screen, self.colour,(self.x,self.y, self.width, self.height))
        if self.letter!= '+' and self.letter!= '-':
            font = pygame.font.SysFont('agencyfb',15,True,False)
        else:
            font = pygame.font.SysFont('agencyfb',25,True,False)

        text = font.render(self.letter, True, black)
        text_rect = text.get_rect(center=(self.x+self.width/2,self.y+self.height/2))
        screen.blit(text, text_rect)


class orbit:
    def __init__(self,screen,colour,x,y,radius,width):
        self.screen = screen
        self.colour = colour
        self.x = x
        self.y = y
        self.width = width
        self.radius = radius
    def draw_circle(self):
        pygame.draw.circle(self.screen,self.colour,(self.x,self.y),self.radius,self.width)




#define colours
##Sun = pygame.draw.circle(screen,Sun,[1000,450],100,0)
Black = (0,0,0)
White = (255,255,255)
Green = (0,255,0)
Red = (255,0,0)
Blue = (0,0,255)
Sun = (255,69,0)
Sun = []
Planet = []


#initialise the engine

pygame.init()

#Opening a window

size = (1920,1080)

screen = pygame.display.set_mode(size)

#set window title

pygame.display.set_caption("Orbit Simulator")

#loop unti the user clicks the close button

done = False
#
x=1000
y=450
Sun.append(orbit(screen,Red,1000,450,100,0))
Planet.append(orbit(screen,White,x,y,50,0))


#

#used to manage how fast the screen updates

clock = pygame.time.Clock()
#------ Main program Loop ------

while not done:

    #--- Main event loop

    for event in pygame.event.get(): #user did something

        if event.type == pygame.QUIT: #if user clicked close

            done = True #flag that we are done and exit the loop



    #------ Game logic should go here ------



    #------ Drawing code should go here -------


    #first, clear the screen to white. Don't put other drawing commands above this or they will be erased with this command.

    screen.fill(Black)


    for i in Sun:
        i.draw_circle()
    for i in Planet:
            r=150
            angle=0
            count = 0
            while angle <= 360:

                angle_radians = math.radians(angle)

                x = int(math.cos(angle_radians)*r)
                y = int(math.sin(angle_radians)*r)


                angle +=1
                count +=1
                print(count)
                x+=1000
                y+=450

                pygame.draw.circle(screen,White,[x,y],10,0)

                print("Position [",x,",",y,"]")



    #update the screen

    pygame.display.flip()

    #------ Limit to 60 frames per second ------

    clock.tick(60)

#------ When the loop ends, quit ------

pygame.quit()

Answer 1

You can make an object rotate around another by using trigonometry or vectors. With vectors you just have to rotate a vector which defines the offset from the rotation center each frame and add it to the position vector (self.pos which is the rotation center) to get the desired self.rect.center coordinates of the orbiting object.

import pygame as pg
from pygame.math import Vector2


class Planet(pg.sprite.Sprite):

    def __init__(self, pos, *groups):
        super().__init__(*groups)
        self.image = pg.Surface((40, 40), pg.SRCALPHA)
        pg.draw.circle(self.image, pg.Color('dodgerblue'), (20, 20), 20)
        self.rect = self.image.get_rect(center=pos)
        self.pos = Vector2(pos)
        self.offset = Vector2(200, 0)
        self.angle = 0

    def update(self):
        self.angle -= 2
        # Add the rotated offset vector to the pos vector to get the rect.center.
        self.rect.center = self.pos + self.offset.rotate(self.angle)


def main():
    pg.init()
    screen = pg.display.set_mode((640, 480))
    screen_rect = screen.get_rect()
    clock = pg.time.Clock()
    all_sprites = pg.sprite.Group()
    planet = Planet(screen_rect.center, all_sprites)
    yellow = pg.Color('yellow')

    while True:
        for event in pg.event.get():
            if event.type == pg.QUIT:
                return

        all_sprites.update()
        screen.fill((30, 30, 30))
        pg.draw.circle(screen, yellow, screen_rect.center, 60)
        all_sprites.draw(screen)

        pg.display.flip()
        clock.tick(60)


if __name__ == '__main__':
    main()
    pg.quit()