Question

考虑到一个充满一些像素的pygame Surface，我想以编程方式在该图像中创建一个alpha通道“窗口”（这样背景就会显示出来）。

很明显，我意识到可以使用位图编辑器轻松完成此操作，问题的关键是作为不同，更复杂的操作的一部分即时进行此操作。

因此，我制作了一个在“全红”和“带孔的红色”图像之间切换的精灵，并尝试通过将完全透明的图像涂抹到基本位图上来动态制作位图窗口。 / p>

我认为正在发生的事情是PyGame没有绘制完全透明的像素，因为它们是透明的！有什么方法可以使它们变薄，从而制成窗户吗？

我尝试添加pygame.BLEND_RGBA_MIN and others（根据Need to blit transparency on a surface in Pygame中的建议），但未能获得期望的结果。

我得到的只是一个以红色为中心的黑色正方形，而不是背景的窗口。

import pygame

# Window size
WINDOW_WIDTH  = 400
WINDOW_HEIGHT = 400
FPS           = 60

# background colours
INKY_BLACK    = (128, 128, 128)

class HoleSprite( pygame.sprite.Sprite ):
    def __init__( self ):
        pygame.sprite.Sprite.__init__( self )
        # Make a full-image (no hole)
        self.base_image = pygame.Surface( ( 32, 32 ), pygame.SRCALPHA )
        self.base_image.fill( ( 255,0,0 ) )
        # Make an image with a see-through window
        self.hole_image = pygame.Surface( ( 32, 32 ), pygame.SRCALPHA )
        self.hole_image.fill( ( 255,0,0 ) )
        self.hole       = pygame.Surface( ( 10, 10 ), pygame.SRCALPHA )
        self.hole.fill( ( 0, 0, 0, 255 ) ) # transparent
        self.hole_image.blit( self.hole, [ 10,10, 10,10 ] ) # punch the middle out?
        # sprite housekeeping
        self.image  = self.base_image
        self.rect   = self.image.get_rect()
        self.rect.x = WINDOW_WIDTH  // 2   # centred
        self.rect.y = WINDOW_HEIGHT // 2
        self.last   = 0

    def update( self ):
        time_ms = pygame.time.get_ticks()
        # FLip the images each second
        if ( time_ms - self.last > 1000 ):
            if ( self.image == self.hole_image ):
                self.image = self.base_image
            else:
                self.image = self.hole_image
            self.last = time_ms


### MAIN
pygame.init()
pygame.font.init()
SURFACE = pygame.HWSURFACE|pygame.DOUBLEBUF|pygame.RESIZABLE
WINDOW  = pygame.display.set_mode( ( WINDOW_WIDTH, WINDOW_HEIGHT ), SURFACE )
pygame.display.set_caption("Hole Srite Test")

anims = pygame.sprite.GroupSingle()
holey = HoleSprite( )
anims.add( holey )

clock = pygame.time.Clock()
done  = False
while not done:

    # Handle user-input
    for event in pygame.event.get():
        if ( event.type == pygame.QUIT ):
            done = True

    # Repaint the screen
    anims.update()
    WINDOW.fill( INKY_BLACK )
    anims.draw( WINDOW )

    pygame.display.flip()
    # Update the window, but not more than 60fps
    clock.tick_busy_loop( FPS )

pygame.quit()

Answer 1

首先：您需要(0,0,0,0)而不是(0,0,0,255)

第二：您必须使用fill(color, rect)直接在红色矩形中创建透明孔。

self.hole_image.fill( (0, 0, 0, 0), (10, 10, 10, 10) )

或者您可以直接在红色表面上绘制透明矩形

pygame.draw.rect(self.hole_image, (0, 0, 0, 0), (10, 10, 10, 10) )

当您在全彩色图像上对透明图像进行反白处理时，它不会替换像素，但会同时混合两种颜色（透明和全色），您会获得全彩色。

blit()具有标志BLEND_ADD，BLEND_SUB，BLEND_MULT等，也许使用其中一个标志可以替换像素，但我从未尝试过。

其他信息：pygame transparency

完整代码：

import pygame

# Window size
WINDOW_WIDTH  = 400
WINDOW_HEIGHT = 400
FPS           = 60

# background colours
INKY_BLACK    = (128, 128, 128)

class HoleSprite( pygame.sprite.Sprite ):
    def __init__( self ):
        pygame.sprite.Sprite.__init__( self )
        # Make a full-image (no hole)
        self.base_image = pygame.Surface( ( 32, 32 ), pygame.SRCALPHA )
        self.base_image.fill( ( 255,0,0 ) )
        # Make an image with a see-through window

        self.hole_image = pygame.Surface( ( 32, 32 ), pygame.SRCALPHA )
        self.hole_image.fill( ( 255,0,0 ) )
        self.hole_image.fill( (0, 0, 0, 0), (10, 10, 10, 10) )
        # OR
        #pygame.draw.rect(self.hole_image, (0, 0, 0, 0), (10, 10, 10, 10) )

        # sprite housekeeping
        self.image  = self.base_image
        self.rect   = self.image.get_rect()
        self.rect.x = WINDOW_WIDTH  // 2   # centred
        self.rect.y = WINDOW_HEIGHT // 2
        self.last   = 0

    def update( self ):
        time_ms = pygame.time.get_ticks()
        # FLip the images each second
        if ( time_ms - self.last > 1000 ):
            if ( self.image == self.hole_image ):
                self.image = self.base_image
            else:
                self.image = self.hole_image
            self.last = time_ms


### MAIN
pygame.init()
pygame.font.init()
SURFACE = pygame.HWSURFACE|pygame.DOUBLEBUF|pygame.RESIZABLE
WINDOW  = pygame.display.set_mode( ( WINDOW_WIDTH, WINDOW_HEIGHT ), SURFACE )
pygame.display.set_caption("Hole Srite Test")

anims = pygame.sprite.GroupSingle()
holey = HoleSprite( )
anims.add( holey )

clock = pygame.time.Clock()
done  = False
while not done:

    # Handle user-input
    for event in pygame.event.get():
        if ( event.type == pygame.QUIT ):
            done = True

    # Repaint the screen
    anims.update()
    WINDOW.fill( INKY_BLACK )
    anims.draw( WINDOW )

    pygame.display.flip()
    # Update the window, but not more than 60fps
    clock.tick_busy_loop( FPS )

pygame.quit()

如何在pygame中对透明图像进行模糊处理以制作Alpha“切出”

1 个答案: