Pygame: Image chasing the mouse cursor from certain length [duplicate]

问题

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Closed 4 months ago.

Initially the image starts moving in the direction (0,0). During each frame, the object looks at the current location of the cursor using pygame.mouse.get_pos() and updates it's direction to be direction = .9*direction + v where v is a vector of length 10 that points from the center of your image to the mouse position.

this is what i have:

    from __future__ import division
import pygame
import sys
import math
from pygame.locals import *


class Cat(object):
    def __init__(self):
        self.image = pygame.image.load('ball.png')
        self.x = 1
        self.y = 1

    def draw(self, surface):
        mosx = 0
        mosy = 0
        x,y = pygame.mouse.get_pos()
        mosx = (x - self.x)
        mosy = (y - self.y)
        self.x = 0.9*self.x + mosx
        self.y = 0.9*self.y + mosy
        surface.blit(self.image, (self.x, self.y))
        pygame.display.update()


pygame.init()
screen = pygame.display.set_mode((800,600))
cat = Cat()
Clock = pygame.time.Clock()

running = True
while running:
    screen.fill((255,255,255))
    cat.draw(screen)
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    pygame.display.update()
    Clock.tick(40)

The issue its that when i'm running the code, the image moves with the mouse cursor, instead of going after it. How can i improve that?

回答1:

If you want, that the image slightly moves in the direction of the mouse, then you have to add a vector to the current position of the image, which points in the direction of the mouse. The length of the has to be less than the distance to the mouse:

dx, dy = (x - self.x), (y - self.y)
self.x, self.y = self.x + dx * 0.1, self.y + dy * 0.1 

this causes that the ball makes a small step to the mouse in each frame.

class Cat(object):
    def __init__(self):
        self.image = pygame.image.load('ball.png')
        self.x = 1
        self.y = 1
        self.t = 0.1

    def draw(self, surface):
        mosx = 0
        mosy = 0
        x,y = pygame.mouse.get_pos()
        dx, dy = (x - self.x), (y - self.y)
        self.x, self.y = self.x + dx * self.t, self.y + dy * self.t
        w, h = self.image.get_size()
        surface.blit(self.image, (self.x - w/2, self.y - h/2))
        pygame.display.update()

---

Minimal example: repl.it/@Rabbid76/PyGame-FollowMouse

See also Move towards target

来源：https://stackoverflow.com/questions/55168892/pygame-image-chasing-the-mouse-cursor-from-certain-length