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Aug 22, 2025 . 1 changed file with 162 additions and 24 deletions.There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -17,10 +17,11 @@ def LinkForce(pos, l1, l2): linkLen = 10.0 dlen = dposLen - linkLen linkForce = dlen * 0.2 return -dposNorm * linkForce def LinkFriction(pos, vel, l1, l2): dpos = pos[l1, :] - pos[l2, :] dposLen = np.pow(np.sum(np.pow(dpos, 2.0)), 0.5) @@ -30,9 +31,24 @@ def LinkFriction(pos, vel, l1, l2): dvel = vel[l1, :] - vel[l2, :] d = dvel.dot(-dposNorm) dv = d * -0.05 vel[l1, :] += dv vel[l2, :] -= dv # Transfer momentum def LinkFriction2(pos, vel, isActive, i): if i-1 >= 0 and i+1 < pos.shape[0] and isActive[i] and isActive[i-1] and isActive[i+1]: #LinkFriction(pos, vel, i+1, i-1) LinkFriction(pos, vel, i, i-1) LinkFriction(pos, vel, i, i+1) else: if i-1 >= 0 and isActive[i] and isActive[i-1]: LinkFriction(pos, vel, i, i-1) if i+1 < pos.shape[0] and isActive[i] and isActive[i+1]: LinkFriction(pos, vel, i, i+1) if __name__=="__main__": @@ -45,67 +61,189 @@ def LinkFriction(pos, vel, l1, l2): color3 = pygame.Color(0, 0, 255) colors = [color1, color2, color3] numNodes = 150 pos = np.zeros((numNodes, 2)) vel = np.zeros((numNodes, 2)) prevPos = pos.copy() notInTray = np.zeros((numNodes,), dtype=np.uint8) isActive = np.zeros((numNodes,), dtype=np.uint8) mass = 1.0 earthMass = 1000.0 earthVel = 0.0 isActive[0] = 1 for i in range(1, 10): pos[i, 0] = 200 pos[i, 1] = 500 + i * 10.0 cursor = 200.0 cursorDirection = 1 for i in range(10, pos.shape[0]): cursor += 10.0 * cursorDirection if cursor >= 220: cursorDirection = -1 if cursor <= 180: cursorDirection = 1 pos[i, 0] = cursor pos[i, 1] = 600 isActive[i] = 1 for i in range(1, 10): notInTray[i] = 1 isActive[i] = 1 frameNum = 0 colourOffset = 0 while True: t = time.time() screen.fill("black") if frameNum < 30: pos[0, 0] = 200 pos[0, 1] = 500 - 10.0 * frameNum # gets to (200, 200) on frame 30 elif frameNum < 60: pos[0, 0] = 300 - 100.0 * math.cos((frameNum-30) * math.pi * 1.0 / 30.0) pos[0, 1] = 200 - 100.0 * math.sin((frameNum-30) * math.pi * 1.0 / 30.0) # gets to (400, 200) on frame 60 elif frameNum < 200: pos[0, 0] = 400 pos[0, 1] = 200 + 10.0 * (frameNum - 60) else: notInTray[0] = 1 vel[0, :] = pos[0, :] - prevPos[0, :] forceOnEarth = 0.0 for i in range(pos.shape[0]): if i == 0 and frameNum < 200: continue totalForce = np.zeros((2,)) # Link forces if i-1 >= 0 and isActive[i] and isActive[i-1]: df = LinkForce(pos, i, i-1) totalForce += df if i+1 < pos.shape[0] and isActive[i] and isActive[i+1]: df = LinkForce(pos, i, i+1) totalForce += df # Fiction #totalForce += -0.001 * vel[i, :] # Gravity totalForce[1] += mass * 0.05 forceOnEarth -= mass * 0.05 accel = totalForce / mass vel[i, :] += accel #if i == 0: # print (totalForce) earthAccel = forceOnEarth / earthMass earthVel += earthAccel # Smooth velocity along chain for j in range(1): for i in range(pos.shape[0]): LinkFriction2(pos, vel, isActive, i) for i in range(pos.shape[0]-1, -1, -1): LinkFriction2(pos, vel, isActive, i) prevPos[:, :] = pos[:, :] pos += vel #print (vel[0, :]) # Check momentum mom = np.zeros((2,)) for i in range(pos.shape[0]): mom += vel[i, :] * mass * isActive[i] mom[1] += earthVel * earthMass #if frameNum > 200: # print (frameNum, mom) # Check for when a node is picked up from tray for i in range(1, pos.shape[0]): if not isActive[i]: continue if not notInTray[i]: if pos[i, 1] > 600.0: pos[i, 1] = 600.0 vel[i, 1] = 0.0 if pos[i, 1] < 590.0: notInTray[i] = 1 if frameNum > 200: dropIndex = None for i in range(pos.shape[0]): if pos[i, 1] < 5000: dropIndex = i break if dropIndex: pos = pos[dropIndex:, :] vel = vel[dropIndex:, :] prevPos = prevPos[dropIndex:, :] notInTray = notInTray[dropIndex:] isActive = isActive[dropIndex:] colourOffset += dropIndex colourOffset = colourOffset % len(colors) countInTray = 0 for i in range(pos.shape[0]): countInTray += 1 - notInTray[i] if countInTray < 20: numToAdd = 10 pos = np.vstack((pos, np.zeros((numToAdd, 2)))) vel = np.vstack((vel, np.zeros((numToAdd, 2)))) prevPos = np.vstack((prevPos, np.zeros((numToAdd, 2)))) notInTray = np.hstack((notInTray, np.zeros((numToAdd,), dtype=np.uint8))) isActive = np.hstack((isActive, np.ones((numToAdd,), dtype=np.uint8))) for i in range(pos.shape[0]-numToAdd, pos.shape[0]): cursor += 10.0 * cursorDirection if cursor >= 220: cursorDirection = -1 if cursor <= 180: cursorDirection = 1 pos[i, 0] = cursor pos[i, 1] = 600 isActive[i] = 1 scale = 2.0 for i in range(1, pos.shape[0]): pygame.draw.line(screen, colors[0], pos[i-1, :] / scale, pos[i, :] / scale, 2) for i in range(pos.shape[0]): pygame.draw.circle(screen, colors[(i+colourOffset) % 3], pos[i, :] / scale, 4.0) for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() frameNum += 1 pygame.display.update() time.sleep(0.02) -
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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,111 @@ # Chain simulation import sys import time import math import numpy as np import pygame from pygame.locals import * def LinkForce(pos, l1, l2): totalForce = np.zeros((3,)) dpos = pos[l1, :] - pos[l2, :] dposLen = np.pow(np.sum(np.pow(dpos, 2.0)), 0.5) dposNorm = dpos.copy() if dposLen > 1e-9: dposNorm /= dposLen linkLen = 10.0 dlen = dposLen - linkLen linkForce = dlen * 0.1 return -dposNorm * linkForce def LinkFriction(pos, vel, l1, l2): dpos = pos[l1, :] - pos[l2, :] dposLen = np.pow(np.sum(np.pow(dpos, 2.0)), 0.5) dposNorm = dpos.copy() if dposLen > 1e-9: dposNorm /= dposLen dvel = vel[l1, :] - vel[l2, :] d = dvel.dot(-dposNorm) dv = d * -0.01 vel[l1, :] += dv if __name__=="__main__": pygame.init() screen = pygame.display.set_mode((1024,1024)) color1 = pygame.Color(255, 0, 0) color2 = pygame.Color(0, 255, 0) color3 = pygame.Color(0, 0, 255) colors = [color1, color2, color3] numNodes = 50 pos = np.zeros((numNodes, 2)) vel = np.zeros((numNodes, 2)) prevPos = pos.copy() for i in range(1, numNodes): pos[i, 0] = 200 pos[i, 1] = 100 + i * 10.0 while True: t = time.time() screen.fill("black") pos[0, 0] = 200+100.0*math.cos(t*math.pi/2.0) pos[0, 1] = 100 vel[0, :] = pos[0, :] - prevPos[0, :] for i in range(1, numNodes): totalForce = np.zeros((2,)) # Link forces df = LinkForce(pos, i, i-1) totalForce += df if i+1 < numNodes: df = LinkForce(pos, i, i+1) totalForce += df # Fiction totalForce += -0.01 * vel[i, :] # Gravity mass = 1.0 totalForce[1] += mass * 0.05 accel = totalForce / mass vel[i, :] += accel for i in range(1, numNodes): LinkFriction(pos, vel, i, i-1) if i+1 < numNodes: LinkFriction(pos, vel, i, i+1) prevPos[:, :] = pos[:, :] pos += vel for i in range(1, numNodes): pygame.draw.line(screen, colors[0], pos[i-1, :], pos[i, :], 2) for i in range(numNodes): pygame.draw.circle(screen, colors[i % 3], pos[i, :], 4.0) for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() pygame.display.update() time.sleep(0.02)