为什么 Processing.py 跳过数组的倒数第二个项目？

Question

我一直在用 Processing 做一些抽象艺术风格的东西。左键是放置一个点，再次点击会随机生成一条线，右键是一个新的点。

当我使用向上和向下箭头选择笔颜色时出现问题。当我使用这些键时，倒数第二个项目（黑色或粉红色）被跳过。附上代码。

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

您的第一个 if 在每种情况下都会影响您的第二个。对于UP，如果selector为6，则变为7，然后匹配selector == 7；对于DOWN，如果selector为1，则变为0，然后匹配selector == 0.

使用elif使它们独占：

if selector < 8:
    fill(fillcolors[selector])
    selector += 1
<b>el</b>if selector == 7:
    fill(fillcolors[selector])
    selector = 0

if selector > 0:
    fill(fillcolors[selector])
    selector -= 1
<b>el</b>if selector == 0:
    fill(fillcolors[selector])
    selector = 7

你的第一个条件应该是 if selector < 7 而不是 8。

为什么 Processing.py 跳过数组的倒数第二个项目？

Why is Processing.py skipping the second-to-last item of my array?

python

processing