问题
I want to change the colour of a rect dynamically during runtime. Currently set_colour
is filling all of the pixels of the surface with a single colour value. This works, but an issue arises when a method like set_outline
is called, which modifies the transparency of the surface.
class Rectangle(pg.sprite.Sprite):
def __init__(self):
pg.sprite.Sprite.__init__(self)
self.original_image = pg.Surface((10, 10))
self.image = self.original_image
self.rect = self.image.get_rect()
def set_colour(self, colour_value):
self.colour = colour_value
self.image.fill(self.colour)
self.original_image.fill(self.colour)
def set_outline(self, thickness):
self.thickness = thickness
size = self.image.get_size()
calc = thickness/100
p_width, p_height = size[0], size[1]
width, height = size[0]*calc, size[1]*calc
self.image = self.image.convert_alpha()
center_x, center_y = (p_width//2)-(width//2), (p_height//2)-(height//2)
pg.draw.rect(self.image, (0, 0, 0, 0), (center_x, center_y, width, height))
Now if I try to change the colour of that rect during runtime, it will overwrite all of those transparent pixels created in set_outline
.
Is there a way to mask or blend the colour on to the rect, so it's not replacing any of the transparency?
回答1:
You can achieve this by 2 steps. self.original_image
contains the filled rectangle with the desired color:
self.original_image.fill(self.colour)
Generate a completely white rectangle and transparent areas. Blend the rectangle with (self.image
) and the blend mode BLEND_MAX
(see pygame.Surface.blit):
whiteTransparent = pg.Surface(self.image.get_size(), pg.SRCALPHA)
whiteTransparent.fill((255, 255, 255, 0))
self.image.blit(whiteTransparent, (0, 0), special_flags=pg.BLEND_MAX)
Now the rectangle is completely white, but the transparent areas are kept. Use the blend mode BLEND_MULT
and blend self.original_image
with self.image
to get the desired result:
self.image.blit(self.original_image, (0, 0), special_flags=pg.BLEND_MULT)
Minimal example: repl.it/@Rabbid76/PyGame-ChangeColorOfSpriteArea
import pygame as pg
class Rectangle(pg.sprite.Sprite):
def __init__(self):
pg.sprite.Sprite.__init__(self)
self.original_image = pg.Surface((150, 150))
self.image = self.original_image
self.rect = self.image.get_rect(center = (150, 150))
def set_colour(self, colour_value):
self.colour = colour_value
self.original_image.fill(self.colour)
whiteTransparent = pg.Surface(self.image.get_size(), pg.SRCALPHA)
whiteTransparent.fill((255, 255, 255, 0))
self.image.blit(whiteTransparent, (0, 0), special_flags=pg.BLEND_MAX)
self.image.blit(self.original_image, (0, 0), special_flags=pg.BLEND_MULT)
def set_outline(self, thickness):
self.thickness = thickness
size = self.image.get_size()
calc = thickness/100
p_width, p_height = size[0], size[1]
width, height = size[0]*calc, size[1]*calc
self.image = self.image.convert_alpha()
center_x, center_y = (p_width//2)-(width//2), (p_height//2)-(height//2)
pg.draw.rect(self.image, (0, 0, 0, 0), (center_x, center_y, width, height))
pg.init()
window = pg.display.set_mode((300, 300))
clock = pg.time.Clock()
sprite = Rectangle()
sprite.set_colour((255, 0, 0, 255))
sprite.set_outline(50)
group = pg.sprite.Group(sprite)
colorVal = 0
colorAdd = 5
run = True
while run:
clock.tick(60)
for event in pg.event.get():
if event.type == pg.QUIT:
run = False
sprite.set_colour((min(colorVal, 255), max(0, min(511-colorVal, 255)), 0, 255))
colorVal += colorAdd
if colorVal <= 0 or colorVal >= 511:
colorAdd *= -1
window.fill(0)
group.draw(window)
pg.display.flip()
来源:https://stackoverflow.com/questions/64190277/changing-colour-of-a-surface-without-overwriting-transparency