Почему этот скрипт Python Pillow не соответствует указанному мной альфа-значению для плавного перехода к цвету фона? ⇐ Python

[Anonymous]

Я пытался написать сценарий для рисования дуг, которые плавно переходят в цвет фона (см. пример ниже).

Код: Выделить всё

from PIL import Image, ImageDraw
import math
import random

def draw_concentric_circles(size=800, num_circles=15):
# Create a grey background
bg_color = (0, 0, 0, 255)  # Dark grey
img = Image.new('RGBA', (size, size), bg_color)
draw = ImageDraw.Draw(img)

center = size // 2
max_radius = (size // 2) - 40
radii = [int(r) for r in range(50, max_radius, max_radius // num_circles)]

colors = [
(232, 69, 76),  # Red
(117, 176, 217)  # Blue
]

for r in radii:
base_color = random.choice(colors)
# Random position for the break (in radians)
break_pos = random.uniform(0, 2 * math.pi)
gap_half_width = 0.05  # Size of the break

# We draw the circle by connecting tiny segments
# 1000 steps ensures the line looks smooth
steps = 1000
for i in range(steps):
# Current angle
angle = (i / steps) * 2 * math.pi

# Calculate distance from the break to determine alpha
# This logic finds the shortest angular distance to the break
diff = abs(angle - break_pos)
if diff > math.pi:
diff = 2 * math.pi - diff

# If we are inside the "break" zone, don't draw
if diff < gap_half_width:
continue

# Normalize distance for fading:
# Near the break (diff approx gap_half_width) -> Alpha 255 (100%)
# Far from break (diff approx PI) -> Alpha 127 (50%)
# Linear interpolation:
alpha_ratio = 1.0 - (1.5 * (diff / math.pi))
alpha = max(min(int(255 * alpha_ratio), 255), 0)

# Calculate coordinates
x = center + r * math.cos(angle)
y = center + r * math.sin(angle)

# Draw a tiny point/rectangle to represent the segment
# We use a small offset to give the line some thickness
thickness = 5
draw.ellipse([x - thickness, y - thickness, x + thickness, y + thickness],
fill=(base_color[0], base_color[1], base_color[2], alpha), outline=None)

print("Showing..")
img.show()

draw_concentric_circles()

Даёт мне:



Подробнее здесь: https://stackoverflow.com/questions/798 ... -specified