How to find x,y coordinates of a circle in Pygame - math

Question

I am currently trying to create a digital speedometer. The project has come to a screeching halt due to the problem encountered when trying to control the dial. My variable radial_pos is intended to calculate the exact x,y coordinates of each tick of the speedometer and if the user presses K_UP, radial_pos will increase by 1 to show the next tick of the speedometer. However, I'm afraid its been too many years since I've learned the concept of finding the coordinates of a circle, let alone understand it enough to be able to increment it accordingly. Here is my code so far:
import pygame, sys
from pygame.locals import *
pygame.init()
#Screen Resolution
width = 1080
height = 720
#Instrument Characteristics
color = (255,255,255)
background = (0,0,0)
radius_speedometer = 100
weight_speedometer = radius_speedometer-5
#Window Measurements
screen= pygame.display.set_mode((width,height),0,32)
pos_center_x = width/2
pos_center_y = height/2
#Speedometer Dial Position
pos_speedometer_dial_x = pos_center_x - 60
pos_speedometer_dial_y = pos_center_y +60
#Radial Position (hint: ticks on the clock)
'''
radial_pos = ...
'''
while True:
for event in pygame.event.get():
if event.type==QUIT:
pygame.quit()
sys.exit()
if event.type==KEYDOWN:
if event.key==K_DOWN:
radial_pos=-1
if event.key==K_UP:
radial_pos=+1
if event.type==KEYUP:
if event.key==K_DOWN:
radial_pos=0
if event.key==K_UP:
radial_pos=0
screen.lock()
#Speedometer Ring
pygame.draw.circle(screen, color, (pos_center_x,pos_center_y), radius_speedometer)
pygame.draw.circle(screen, background, (pos_center_x,pos_center_y), weight_speedometer)
#Speedometer Dial
pygame.draw.line(screen, color, (pos_center_x,pos_center_y), (pos_speedometer_dial_x, pos_speedometer_dial_y),5)
screen.unlock()
pygame.display.update()
If anyone has any advice for this particular issue, it would greatly appreciated. Thank you for your time.

Answer 1

It seems I have finally found a solution that works well. Here is the most updated code:
import pygame, sys
from pygame.locals import *
from math import *
pygame.init()
#Screen Resolution
width = 1080
height = 720
#Instrument Characteristics
color = (255,255,255)
background = (0,0,0)
radius_speedometer = 100
weight_speedometer = radius_speedometer-5
#Window Measurements
screen= pygame.display.set_mode((width,height),0,32)
pos_center_x = width/2
pos_center_y = height/2
#Speedometer Dial Position
pos_speedometer_dial_x = pos_center_x - 60
pos_speedometer_dial_y = pos_center_y +60
#Radial Position (hint: ticks on the clock)
radial_pos = 70
move_rad = 0
while True:
for event in pygame.event.get():
if event.type==QUIT:
pygame.quit()
sys.exit()
if event.type==KEYDOWN:
if event.key==K_DOWN:
move_rad=-0.01
if event.key==K_UP:
move_rad=+0.01
if event.type==KEYUP:
if event.key==K_DOWN:
move_rad=-0.05
if event.key==K_UP:
move_rad=-0.005
angle = 2.0*pi*radial_pos/120.0
radial_pos+=move_rad
pos_speedometer_dial_x = pos_center_x + (radius_speedometer-10)*sin(angle)
pos_speedometer_dial_y = pos_center_y - (radius_speedometer-10)*cos(angle)
screen.lock()
#Speedometer Ring
pygame.draw.circle(screen, color, (pos_center_x,pos_center_y), radius_speedometer)
pygame.draw.circle(screen, background, (pos_center_x,pos_center_y), weight_speedometer)
#Speedometer Dial
pygame.draw.line(screen, color, (pos_center_x,pos_center_y), (pos_speedometer_dial_x, pos_speedometer_dial_y),5)
screen.unlock()
pygame.display.update()
It's not perfect (such as no zero yet), however we are now much closer to completing the first instrument of the dash cluster!