research/scale/simulated-scale

#!/usr/bin/env python

import sys

ASPECT_RATIO = 4.0 / 3
AUTO_ADJUST = True
SCREENWIDTH = 320
SCREENHEIGHT = 200

def set_screen_size(w, h):
	global window_w, window_h, texture_w, texture_h
	global scale_horiz, scale_vert

	window_w, window_h = w, h

	if AUTO_ADJUST:
		if float(window_w) / window_h > ASPECT_RATIO:
			# widescreen
			new_window_w = int(window_h * ASPECT_RATIO)
			new_window_h = window_h
		else:
			new_window_w = window_w
			new_window_h = int(window_w / ASPECT_RATIO)

		if (window_w, window_h) != (new_window_w, new_window_h):
			window_w, window_h = new_window_w, new_window_h
			#print "Auto-adjusted to %ix%i" % (window_w, window_h)

	scale_horiz = (window_w + SCREENWIDTH - 1) // SCREENWIDTH
	scale_vert = (window_h + SCREENHEIGHT - 1) // SCREENHEIGHT
	texture_w = SCREENWIDTH * scale_horiz
	texture_h = SCREENHEIGHT * scale_vert

def texture_pixel_value(x, y):
	"""Get value at the given texture coordinates."""
	orig_x = x // scale_horiz
	orig_y = y // scale_vert
	# Black/white checkerboard pattern:
	result = (orig_x + orig_y) % 2
	#print "\t(%i, %i) -> %i" % (x, y, result)
	return result

def screen_pixel_value(x, y):
	"""Get pixel value at given texture coordinates."""
	tx_x = float(x * texture_w) / window_w
	tx_y = float(y * texture_h) / window_h
	#print "(%i, %i) -> (%.1f, %.1f) in tx" % (x, y, tx_x, tx_y)

	tx_x1 = tx_x // 1
	tx_x2 = tx_x1 + 1
	tx_y1 = tx_y // 1
	tx_y2 = tx_y1 + 1

	tl = texture_pixel_value(tx_x1, tx_y1)
	tr = texture_pixel_value(tx_x2, tx_y1)
	bl = texture_pixel_value(tx_x1, tx_y2)
	br = texture_pixel_value(tx_x2, tx_y2)

	x_frac = tx_x - tx_x1
	y_frac = tx_y - tx_y1

	t = tl * (1 - x_frac) + tr * x_frac
	#print "\t%.1f between %.1f and %.1f = %.1f" % (x_frac, tl, tr, t)
	b = bl * (1 - x_frac) + br * x_frac
	#print "\t%.1f between %.1f and %.1f = %.1f" % (y_frac, bl, br, b)
	#print "\t%.1f between %.1f and %.1f" % (y_frac, t, b)

	result = t * (1 - y_frac) + b * y_frac

	return result

def is_exact(v):
	frac = min(v, 1 - v)
	return frac < (1 / 256.0)

def bluriness_measure():
	"""Calculate a measure for screen blurriness."""
	num_pixels = window_w * window_h
	num_blurries = 0
	blurriness = 0
	for y in range(window_h):
		for x in range(window_w):
			v = screen_pixel_value(x, y)
			# Maximum blurriness is frac=0.5:
			frac = min(v, 1 - v)
			blurriness += frac / 0.5

			if not is_exact(v):
				num_blurries += 1

	return blurriness / num_pixels, float(num_blurries) / num_pixels

def draw_ascii():
	output_w, output_h = 80, 50

	for y in range(output_h):
		for x in range(output_w):
			v = screen_pixel_value(x, y)
			if is_exact(v):
				if v < 0.5:
					sys.stdout.write(' ')
				else:
					sys.stdout.write('#')
			else:
				if v < 0.5:
					sys.stdout.write('.')
				else:
					sys.stdout.write(':')
		sys.stdout.write('\n')

def draw_floats():
	for y in range(output_h):
		for x in range(10):
			v = screen_pixel_value(x, y)
			print "%.3f" % v,
		print

base_screen_sizes = (
	# Integer vertical scales:
	(267,  200),
	(533,  400),
	(800,  600),
	(1066, 800),
	(1333, 1000),
	(1600, 1200),
	None,
	# Integer horizontal scales:
	(320,  240),
	(640,  480),
	(960,  720),
	(1280, 960),
	(1600, 1200),
	None,
	# Other modes we care about:
	(1024, 768),   None,
	(1920, 1080),  None,
)

#set_screen_size(int(sys.argv[1]), int(sys.argv[2]))
#draw_ascii()

for i in range(len(base_screen_sizes) - 1):
	size1, size2 = base_screen_sizes[i:i+2]
	if size1 is None:
		continue

	def fraction_between_sizes(frac):
		return (
			int(size1[0] * (1 - frac) + size2[0] * frac),
			int(size1[1] * (1 - frac) + size2[1] * frac),
		)

	sizes = [size1]
	if size2 is not None:
		sizes.extend((
			fraction_between_sizes(0.25),
			fraction_between_sizes(1.0 / 3),
			fraction_between_sizes(0.5),
			fraction_between_sizes(2.0 / 3),
			fraction_between_sizes(0.75),
		))

	for size in sizes:
		set_screen_size(size[0] + 1, size[1])

		int_mul = ((window_w % SCREENWIDTH) == 0
		        or (window_h % SCREENHEIGHT) == 0)
		blurriness, num_blurries = bluriness_measure()
		print "%i,%i,%.5f,%.5f,%s,%s" % (
			window_w, window_h, blurriness, num_blurries,
			"e" if (window_w % SCREENWIDTH) == 0 else "n",
			"e" if (window_h % SCREENHEIGHT) == 0 else "n")