为什么Processing.py会跳过数组的第二个到最后一个项？

Question

我一直在制作一种抽象艺术风格的东西。左键单击是放置一个点，再次单击它将生成一条随机线，右键单击生成一个新点

当我使用上下箭头选择钢笔颜色时，问题就出现了。使用这些键时，将跳过倒数第二项（黑色或粉色）。代码见附件

def setup():
    size(750, 750)
    background(255)
    global clicks
    global selector
    global fillcolors
    fillcolors = [0x80FFFFFF, 0x80000000, 0x80FF0000, 0x8000FF00, 0x800000FF, 0x80FFFF00, 0x80FF00FF, 0x8000FFFF]
    selector = 1
    clicks = 0
    ellipseMode(CENTER)
    fill(255, 255, 255, 128)

def draw():
    ellipse(50, 50, 50, 50)

def mousePressed():
    global x
    global y
    global clicks
    if (mouseButton == LEFT) and (clicks == 0):
        x = mouseX
        y = mouseY
        clicks = 1
    if (mouseButton == LEFT) and (0 < clicks < 11):
        line(x, y, x+random(-300, 300), y+random(-300, 300))
        clicks += 1
    if (mouseButton == LEFT) and (clicks == 11):
        wide = random(300)
        clicks = 1
        line(x, y, x+random(-300, 300), y+random(-300, 300))
        ellipse(x, y, wide, wide)
    if mouseButton == RIGHT:
        clicks = 0

def keyPressed():              # this is the color selector area.
    global selector
    global fillcolors
    global clicks
    clicks = 0
    if key != CODED:
        background(255)
    elif key == CODED:
        if keyCode == UP:
            if selector < 8:                  # something in here is causing the second-to-last item of the array to be skipped.
                fill(fillcolors[selector])
                selector += 1
            if selector == 7:
                fill(fillcolors[selector])
                selector = 0
        if keyCode == DOWN:
            if selector > 0:
                fill(fillcolors[selector])
                selector -= 1
            if selector == 0:
                fill(fillcolors[selector])
                selector = 7

Answer 1

在每种情况下，你的第一个if都会影响你的第二个。对于UP，如果selector为6，则变为7，然后匹配selector == 7；对于DOWN，如果选择器为1，则它变为0，然后匹配selector == 0

使用elif使它们成为独占的：

if selector < 8:
    fill(fillcolors[selector])
    selector += 1
elif selector == 7:
    fill(fillcolors[selector])
    selector = 0

if selector > 0:
    fill(fillcolors[selector])
    selector -= 1
elif selector == 0:
    fill(fillcolors[selector])
    selector = 7

你的第一个条件应该是if selector < 7，而不是8