Pygame鼠标速度

Question

我是新的编码和pygame，我正在寻找代码来检查鼠标是否以一定的速度移动。如果是，那就退出游戏

if the mouse speed is greater than say 10 pixels per second
     Run = False

Answer 1

您可以通过pygame.mouse.get_pos()函数跟踪鼠标位置的每一帧，当鼠标位置发生变化时，请检查pygame.time.get_ticks()的时间

比如：

MAX_SPEED = 50

previous_mouse_position = None
previous_sample_time    = None
...

current_mouse_pos = pygame.mouse.get_pos()
if ( previous_mouse_position != current_mouse_pos ):
    # mouse has moved
    pixels_movement = distance( previous_mouse_position, current_mouse_pos )
    time_now        = pygame.time.get_ticks()
    movement_time   = ( time_now - previous_sample_time ) / 1000  # milliseconds -> seconds
    movement_speed = pixels_movement / movement_time
    if ( movement_speed > MAX_SPEED ):
        doSomething()

elif ( previous_mouse_position == None ):
    # No previous recorded position
    previous_mouse_position = current_mouse_pos
    previous_sample_time    = pygame.time.get_ticks()

当然euclidian distance between two points可以相当容易地计算出来

编辑：

import math

def distance( point1, point2 ):
    """ Return the Euclidian distance between two points 
        Ref: https://en.wikipedia.org/wiki/Euclidean_distance#Two_dimensions """
    # NOTE: this code hasn't been tested
    p1x, p1y  = point1
    p2x, p2y  = point2
    x_squared = ( p2x - p1x ) * ( p2x - p1x )
    y_squared = ( p2y - p1y ) * ( p2y - p1y )
    pixel_dist= math.sqrt( x_squared + y_squared )
    return pixel_dist

Answer 2

MOUSEMOTION事件有一个属性rel，它表示鼠标相对于其先前位置移动了多少。使用这个属性，我们可以使用毕达哥拉斯定理来计算速度（**在Python中表示功率）。因此，在事件循环中，可以执行以下操作：

for event in pygame.event.get():
    if event.type == pygame.MOUSEMOTION:
        dx, dy = event.rel
        speed = (dx ** 2 + dy ** 2) ** (1/2)  # Pythagoras theorem.
        if speed >= MAX_SPEED:
            quit()  # Or show quit screen or whatever.

确保在循环之前定义MAX_SPEED（例如，作为全局变量）

这种方法的一个问题是，第一个事件将有一个相对于原点的位置，即当游戏开始时，如果鼠标位于（100100），那么rel属性将是（100100）

因为您可能不想在应用程序开始时就强制执行游戏规则，所以这应该不是问题。但是，如果您希望在执行此规则的情况下打开游戏，则需要跳过第一个MOUSEMOTION事件。这可以通过检查布尔值来实现

# Define this globally (or somewhere where it will only be set on startup).
# Also, use a better name than 'first'. Something that represent the logic for your game. 
first = False


for event in pygame.event.get():
    if event.type == pygame.MOUSEMOTION:
        dx, dy = event.rel
        speed = (dx ** 2 + dy ** 2) ** (1/2)  # Pythagoras theorem.
        if speed >= MAX_SPEED and first:
            quit()  # Or show quit screen or whatever.
        first = True