The over operator

For blending between two colors, here's a bit of mixing code:

	# color_filters.py
	filter_color = {'r': 0.9, 'g': 0.2, 'b': 0.1}
	background_color = {'r': 0.9, 'g': 0.9, 'b': 0.4}
	filter_alpha = 0.7
	def over_operator(alpha, color1, color2):
	color_out = {}
	for component in color1.keys():
	color_out[component] = \
	(alpha * color1[component]) + ((1.0-alpha) * color2[component])
	return color_out
	new_color = over_operator(filter_alpha, filter_color, background_color)
	for component in 'rgb':
	print(component, new_color[component])

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i tend to like this a little bit more, especially if I can reuse the color lambda

	# color_filters.py
	# full version https://gist.github.com/zeffii/5355384
	col = lambda r, g, b : dict(zip('rgb', (r, g, b)))
	filter_color = col(0.9, 0.2, 0.1)
	background_color = col(0.9, 0.9, 0.4)
	filter_alpha = 0.7

view raw abbreviated_over_operator.py hosted with ❤ by GitHub

Or another lambda version https://gist.github.com/zeffii/5354106 abbreviated here:

	# color_filters.py
	col = lambda rgb : dict(zip('rgb', rgb))
	filter_color = col((0.9, 0.2, 0.1))
	background_color = col((0.9, 0.9, 0.4))
	filter_alpha = 0.7
	# rest is the same

view raw over_operator.py hosted with ❤ by GitHub