First commit

RigidMass.py

+import math
+
+G = 6.67408E-11
+
+class RigidMass:
+	def __init__(self, mass, vx, vy, x, y, tick):
+		self.mass = mass
+		self.vx = vx
+		self.vy = vy
+		self.x = x
+		self.y = y
+		self.dvx, self.dvy = 0, 0
+		self.tick = tick #tick length, in seconds
+
+	def gravity(self, p): #p is other particle
+		v = -G * p.mass / self.distance_squared(p) * self.tick
+
+		#print(self.distance_squared(p))
+		#self.v = v #debugging
+
+		dx = self.x - p.x
+		dy = self.y - p.y
+		hyp = math.sqrt(dx**2 + dy**2)
+		self.dvx += v * (dx) / hyp
+		self.dvy += v * (dy) / hyp
+
+	def process_tick(self):
+		self.vx += self.dvx
+		self.vy += self.dvy
+		self.dvx, self.dvy = 0, 0
+		self.x += self.vx * self.tick
+		self.y += self.vy * self.tick
+		
+	def distance_squared(self, p):
+		return abs((self.x - p.x)**2 + (self.y - p.y)**2)

main.py

+from RigidMass import RigidMass
+from PIL import Image
+from PIL import ImageFont
+from PIL import ImageDraw 
+import random
+import math
+
+
+
+
+outImg = Image.new("RGB", [1000, 1000])
+def storePixels(name, things):
+	global outImg
+	#outImg = Image.new("RGB", [1000, 1000])
+	w, h = 1000, 1000
+	for thing in things:
+		if thing.x > 0 and thing.y > 0 and thing.x < 1000 and thing.y < 1000:
+			outImg.putpixel((int(thing.x), int(thing.y)), 16581370*255)
+	#outImg.save(name)
+
+#sun = RigidMass(  500000000000000, 0, -5, 500, 500, 0.05)
+#earth = RigidMass(500000000000000, 0, 5, 250, 500, 0.05)
+
+tick_time = 0.05
+
+num_stars = 1000
+stars = []
+for i in range(num_stars):
+	#give each star some angular velocity
+	#did some cool algebra on paper
+	x = random.randint(375, 625)
+	y = random.randint(375, 625)
+	dx = x - 500
+	dy = y - 500
+
+	if abs(dy) <= abs(dx):
+		vy = 3 * random.random()
+		vx = -vy * dy / dx
+	else:
+		vx = 3 * random.random()
+		vy  = -vx * dx / dy
+
+	#this makes the circle rotate together
+	#without it, one half rotates in the opposite direction
+	#the two halves are separated by the y=x line
+	#I have no idea why that happens, but this fixes it.
+	if y < x:
+		vx = -vx
+		vy = -vy
+	stars.append(RigidMass(50000000000, vx, vy, x, y, tick_time))
+
+for i in range(0, 50000):
+	for a in range(0, num_stars):
+		for b in range(0, num_stars):
+			if not a == b and abs(stars[a].x - stars[b].x) > 0.5 and abs(stars[a].y - stars[b].y) > 0.5:
+				stars[a].gravity(stars[b])
+
+	for a in range(0, num_stars):
+		stars[a].process_tick()
+		
+	storePixels(str(i) + ".png", stars)
+	if i % 10 == 0:
+		draw = ImageDraw.Draw(outImg)
+		draw.text((0, 0),"t=" + str(i * tick_time) + "s", (255,255,255))
+		outImg.save("img/" + str(i // 10) + ".png")
+		outImg = Image.new("RGB", [1000, 1000])
+
+outImg.save("final.png")