Generates bitmap of equilateral triangle

triangle.py

import math

from PIL import Image


def triangle(length=20):
    im = Image.new("RGB", (length, length), (255, 255, 255))
    for x in range(length):
        for y in range(length):
            x_n, y_n = x - length / 2, length - y
            if (y_n <= 2 / math.sqrt(2) * x_n + length / math.sqrt(2) and
                    -2 / math.sqrt(2) * x_n + length / math.sqrt(2) >= y_n >= 0):
                r = round(255 / length * (length - x))
                b = round(255 / length * (length - y))
                g = abs(255 - r - b)
                im.putpixel((x, y), (r, g, b))

    im.save("triangle_" + str(length) + ".png")

# triangle(500)