pygame blitting/camera test

from pygame import *
import random

init()
screen = display.set_mode((0,0), FULLSCREEN)
sx, sy = screen.get_size()

wx, wy = 4000, 4000
worldmap = Surface((wx, wy))

worldmap.fill((40, 40, 40))
for _ in range(1000):
	c = random.randint(20, 60)
	x = random.randint(0, wx)
	y = random.randint(0, wy)
	r = random.randint(wx // 20, wx // 10)
	draw.circle(worldmap, (c, c, c), (x, y), r)

playing = True
px, py = wx // 2, wy // 2
clock = time.Clock()
f = font.Font(None, 64)
while not any(e.type == KEYDOWN and e.key == K_ESCAPE for e in event.get()):
	dt = 0.001 * clock.tick()
	k = key.get_pressed()

	# Player position in world coordinates
	px += (k[K_RIGHT] - k[K_LEFT]) * 1000 * dt
	py += (k[K_DOWN] - k[K_UP]) * 1000 * dt
	px = min(max(px, 0), wx)
	py = min(max(py, 0), wy)

	# Camera position (ie center of the screen in world coordinates)
	cx = min(max(px, sx//2), wx-sx//2)
	cy = min(max(py, sy//2), wy-sy//2)

	# draw world map
	screen.blit(worldmap, (sx//2 - cx, sy//2 - cy))
	# draw player
	draw.circle(screen, (0, 0, 100), (int(sx//2 + px - cx), int(sy//2 + py - cy)), 20)
	# fps counter
	screen.blit(f.render("%.1ffps" % clock.get_fps(), True, (255, 255, 255)), (0, 0))

	display.flip()

quit()