how do I draw this rect?

Question

I m having trouble with function advanced_health in class Player for some reason it doesnt work when reducing the health it should draw an orange rect but it doesnt draw anything but it does draw the health when adding health pygame.draw.rect(screen,transition_color,transition_bar) How do I fix this?

import pygame, sys

class Player(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((40,40))
        self.image.fill((200,30,30))
        self.rect = self.image.get_rect(center = (400,400))
        self.current_health = 200
        self.target_health = 500
        self.max_health = 1000
        self.health_bar_length = 400
        self.health_ratio = self.max_health / self.health_bar_length
        self.health_change_speed = 5

    def get_damage(self,amount):
        if self.target_health > 0:
            self.target_health -= amount
        if self.target_health < 0:
            self.target_health = 0

    def get_health(self,amount):
        if self.target_health < self.max_health:
            self.target_health += amount
        if self.target_health > self.max_health:
            self.target_health = self.max_health

    def update(self):
        self.basic_health()
        self.advanced_health()
        
    def basic_health(self):
        pygame.draw.rect(screen,(255,0,0),(10,10,self.target_health / self.health_ratio,25))
        pygame.draw.rect(screen,(255,255,255),(10,10,self.health_bar_length,25),4)

basic_health function is the upper bar that doesnt look that good and advanced helth is the one that doesnt work

    def advanced_health(self):
        transition_width = 0
        transition_color = (255,0,0)

        if self.current_health < self.target_health:
            self.current_health += self.health_change_speed
            transition_width = int((self.target_health - self.current_health) / self.health_ratio)
            transition_color = (0,255,0)

        if self.current_health > self.target_health:
            self.current_health -= self.health_change_speed 
            transition_width = int((self.target_health - self.current_health) / self.health_ratio)
            transition_color = (255,255,0)

        health_bar_width = int(self.current_health / self.health_ratio)
        health_bar = pygame.Rect(10,45,health_bar_width,25)
        transition_bar = pygame.Rect(health_bar.right,45,transition_width,25)
        
        pygame.draw.rect(screen,(255,0,0),health_bar)
        pygame.draw.rect(screen,transition_color,transition_bar)    
        pygame.draw.rect(screen,(255,255,255),(10,45,self.health_bar_length,25),4)  

it doesnt work above this text

pygame.init()
screen = pygame.display.set_mode((800,800))
clock = pygame.time.Clock()
player = pygame.sprite.GroupSingle(Player())

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
            pygame.quit()
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                player.sprite.get_health(200)
            if event.key == pygame.K_DOWN:
                player.sprite.get_damage(200)

    screen.fill((30,30,30))
    player.draw(screen)
    player.update()
    pygame.display.update()
    clock.tick(60)

Answer 1

It seems that transition_width is negative. You have to normalize the rectangle:

transition_bar = pygame.Rect(health_bar.right,45,transition_width,25)
transition_bar.normalize()