Python 暴力绘制RGB三色图 Pygame框架下
昨天水群，有个群友想要绘制一个三色图，如下
对于Pygame或者其他的GUI框架，画面显示都是依靠图像的一层层覆盖来实现刷新的。所以当绿色的圆覆盖蓝色的圆时，颜色不会想象中的叠加。
最开始的想法是（未实现，具体实现方法请下翻），根据三色叠加的原理，依次绘制三个圆，判断叠加区域，叠加区域的色彩值=(R1+R2, G1+G2, B1+B2)，例如蓝色(0,0,255)与红色(255,0,0)叠加，最终色彩值为(255,0,255)。同理，中间白色区域就是三个颜色的叠加，最终为(255,255,255)也就是白色。
具体方法如上图，每次绘制后建立一个surface的副本，然后再绘制下一个圆，接着依次对比原surface，找出颜色改变的地方，并且此点原先不能为白色。从而判断这个点就所处在叠加区域，接着在将原点的RGB与现点的RGB相加，即可做到颜色的叠加。
但是这种方法想想都头疼，也没创建过surface副本的经验。正在准备硬着头皮上时，有个群友说”这个时候肯定要用数学知识呀，数学总是在该用时想不到”，是啊，确实，用数学方法应该是个不错的办法。
那么就来考虑新办法，但是接下来那个群友的数学方法就比较复杂了，他打算以中间白色区域构成一个等边三角形，然后画弧，具体的我也没太了解，但是看起来也比较复杂。
; （最后实现方法）
我的想法是，遍历所有像素点，判断该点与三个圆心的距离，如果距离小于圆的半径，则该点在此圆内，给予该点相应色彩值，如果同时在两个圆内，那么该点相应色彩值就是两个圆颜色的叠加后应有的颜色，同理三个圆（所以说暴力硬算，不过那是电脑该干的了。
说干就干。
- 引入pygame模块，并初始化
import pygame
from pygame import *
pygame.init()
- 确定三个圆的圆心坐标，及半径值，简要在图中画出其所在位置
circle = [(200, 100), (150, 200), (250, 200)]
r = 100
for i in circle:
pygame.draw.circle(window, (255, 255, 255), i, r, 10)
- 创建数组，用来判断三个圆对该点的包含情况，初始值都为False
in_circle = [False, False, False]
- 开始遍历，核心部分
for y in range(0, 400):
for x in range(0, 400):
in_circle = [False, False, False]
for i in range(3):
if ((circle[i][0] - x)**2 + (circle[i][1] - y)**2) r*r:
in_circle[i] = True
if in_circle[0] == False and in_circle[1] == False and in_circle[2] == False:
window.set_at((x, y), (255, 255, 255))
elif in_circle[0] == True and in_circle[1] == False and in_circle[2] == False:
window.set_at((x, y), (0, 0, 255))
elif in_circle[0] == False and in_circle[1] == True and in_circle[2] == False:
window.set_at((x, y), (0, 255, 0))
elif in_circle[0] == False and in_circle[1] == False and in_circle[2] == True:
window.set_at((x, y), (255, 0, 0))
elif in_circle[0] == True and in_circle[1] == True and in_circle[2] == False:
window.set_at((x, y), (0, 255, 255))
elif in_circle[0] == False and in_circle[1] == True and in_circle[2] == True:
window.set_at((x, y), (255, 255, 0))
elif in_circle[0] == True and in_circle[1] == False and in_circle[2] == True:
window.set_at((x, y), (255, 0, 255))
elif in_circle[0] == True and in_circle[1] == True and in_circle[2] == True:
window.set_at((x, y), (255, 255, 255))
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
pygame.display.update()
- 最后，在绘制完后，不让界面关闭，加入一个while循环
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
break
- 最终效果：（要慢一些，我这个快进了哈哈
- 所有代码
import pygame
from pygame import *
pygame.init()
window = pygame.display.set_mode((400, 400))
pygame.display.set_caption("RGB")
circle = [(200, 100), (150, 200), (250, 200)]
r = 100
in_circle = [False, False, False]
for i in circle:
pygame.draw.circle(window, (255, 255, 255), i, r, 10)
for y in range(0, 400):
for x in range(0, 400):
in_circle = [False, False, False]
for i in range(3):
if ((circle[i][0] - x)**2 + (circle[i][1] - y)**2) r*r:
in_circle[i] = True
if in_circle[0] == False and in_circle[1] == False and in_circle[2] == False:
window.set_at((x, y), (255, 255, 255))
elif in_circle[0] == True and in_circle[1] == False and in_circle[2] == False:
window.set_at((x, y), (0, 0, 255))
elif in_circle[0] == False and in_circle[1] == True and in_circle[2] == False:
window.set_at((x, y), (0, 255, 0))
elif in_circle[0] == False and in_circle[1] == False and in_circle[2] == True:
window.set_at((x, y), (255, 0, 0))
elif in_circle[0] == True and in_circle[1] == True and in_circle[2] == False:
window.set_at((x, y), (0, 255, 255))
elif in_circle[0] == False and in_circle[1] == True and in_circle[2] == True:
window.set_at((x, y), (255, 255, 0))
elif in_circle[0] == True and in_circle[1] == False and in_circle[2] == True:
window.set_at((x, y), (255, 0, 255))
elif in_circle[0] == True and in_circle[1] == True and in_circle[2] == True:
window.set_at((x, y), (255, 255, 255))
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
pygame.display.update()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
exit()
break
以上，over！
有更好的方法欢迎评论告知，我向你敬礼呀~
或许我该去学学算法了（
具体的应该还能再优化？
https://blog.csdn.net/zx3517288/article/details/53326420
Original: https://blog.csdn.net/qq_48016058/article/details/118770669
Author: ClariS –
Title: Python 暴力绘制RGB三色图 Pygame框架下实例
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