Pygame accurate shooting in game - math

Question

I have simplified my code to the bare necessities to make it easier to understand. All that happens is when a certain area is clicked a bullet fires to around that area originating from a white square. The problem is that I don't want the bullet to hit around the area clicked, but exactly where it was clicked.
Here is my code:
import pygame, sys, time, random, math
from pygame.locals import *
background = (0, 0, 0)
entity_color = (255, 255, 255,255)
listLaser = pygame.sprite.Group()
player_x, player_y = 0, 0
move_player_x, move_player_y = 0, 0
all_sprites_list = pygame.sprite.Group()
class Entity(pygame.sprite.Sprite):
"""Inherited by any object in the game."""
def __init__(self, x, y, width, height):
pygame.sprite.Sprite.__init__(self)
self.x = x
self.y = y
self.width = width
self.height = height
# This makes a rectangle around the entity, used for anything
# from collision to moving around.
self.rect = pygame.Rect(self.x, self.y, self.width, self.height)
class User(Entity):
"""
Player controlled or AI controlled, main interaction with
the game
"""
def __init__(self, x, y, width, height):
super(User, self).__init__(x, y, width, height)
self.image = pygame.Surface([20, 37])
self.image.fill(entity_color)
self.image.blit(self.image, (0, 0))
class Player(User):
"""The player controlled Character"""
def __init__(self, x, y, width, height):
super(Player, self).__init__(x, y, width, height)
pass
class Bullet(pygame.sprite.Sprite):
def __init__(self, mouse, player):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.Surface([4, 10])
self.image.fill(entity_color)
self.mouse_x, self.mouse_y = mouse[0], mouse[1]
self.player = player
self.rect = self.image.get_rect()
def update(self):
'''
Gets vector from the two points and gets a direction and sends the bullet that way using player and clicked points
'''
speed = -4.
range = 200
distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]]
norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2)
direction = [distance[0] / norm, distance[1 ] / norm]
bullet_vector = [direction[0] * speed, direction[1] * speed]
self.rect.x -= bullet_vector[0]
self.rect.y -= bullet_vector[1]
pygame.init()
pygame.display.set_caption('Race')
window_width = 800
window_height = 700
screen = pygame.display.set_mode((window_width, window_height))
player = Player(20, window_height / 2, 40, 37)
all_sprites_list.add(player)
while True: # the main game loop
for event in pygame.event.get():
if event.type == MOUSEBUTTONDOWN:
bullet = Bullet(pygame.mouse.get_pos(), [player.rect.x, player.rect.y])
bullet.rect.x = player.rect.x
bullet.rect.y = player.rect.y
all_sprites_list.add(bullet)
listLaser.add(bullet)
for ent in all_sprites_list:
ent.update()
screen.fill(background)
all_sprites_list.draw(screen)
pygame.display.flip()
pygame.display.update()
I really need help modifying my code to get the bullet to hit exactly at the clicked area

Answer 1

pygame.Rects can't have floating point numbers as their x, y attributes/coordinates and pygame just truncates the floats that you assign to the rect, so the direction becomes inaccurate.
You need to store the actual position in separate attributes (for example self.posx) and then update these attributes first and afterwards the self.rect.
class Bullet(pygame.sprite.Sprite):
def __init__(self, mouse, player):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.Surface([4, 10])
self.image.fill(entity_color)
self.mouse_x, self.mouse_y = mouse[0], mouse[1]
self.player = player
self.posx = self.player[0]
self.posy = self.player[1]
self.rect = self.image.get_rect()
speed = -4.
distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]]
norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2)
direction = [distance[0] / norm, distance[1 ] / norm]
self.bullet_vector = [direction[0] * speed, direction[1] * speed]
def update(self):
self.posx -= self.bullet_vector[0]
self.posy -= self.bullet_vector[1]
self.rect.topleft = self.posx, self.posy
You also don't need to calculate the bullet_vector every frame unless the bullets should be able to change their direction (like a homing missile).