What could be causing 'array.array assignment index out of range' error?

dallas_borealis

I'm attempting to do Dan Shiffman's Pixel Array in Python but get the error after just a few iterations. Here's the code:

inc = 0.01
def setup():
    size(6, 5)

def draw():
    # background(50)
    global inc
    yoff = 0
    loadPixels()
    for y in range(height-1):
        xoff = 0
        for x in range(width):
            idx = (x + y * width) * 4
            r = noise(xoff, yoff) * 255
            pixels[idx+0] = r
            pixels[idx+1] = r
            pixels[idx+2] = r
            pixels[idx+3] = 255
            xoff += inc
        yoff += inc
    updatePixels()

The error appears here: pixels[idx+2] = r

Thanks for any help!

~dallas_borealis

GoToLoop

pixels[] in Processing is made outta 32-bit (4-byte) aRGB color values: L-)

1. https://Processing.org/reference/pixels.html
2. https://Processing.org/reference/color_datatype.html

dallas_borealis

Huh. You can't address the individual RGB values for a specific pixel in the Pixel Array. Good to know. Thanks.

But how does his work?

GoToLoop

In order to get the individual aRGB values, we use bitshifting operator >>:
http://py.Processing.org/reference/rightshift.html

Plus bitwise operator & in order to mask off the left-side remaining bits from the original color value: http://py.Processing.org/reference/bitwiseAND.html

kfrajer

In the reference, you should check:

• red()
• green()
• blue()
• alpha()
• imageMode()
• The analog functions for HSB mode

Kf