def __init__(self, position, mass, charge, timeInterval): """Takes position as list [x, y], mass, charge (sign indicates positive or negative), and the amount of time that passes between value calculations (the time between frames shown)""" self.moveState = False self.pos = position self.mass = mass self.velocity = [0, 0] self.charge = charge self.timeInterval = timeInterval #setting radius to 20x the mass of particle, can change later if self.charge < 0: self.graphicalObject = GraphicalParticle(self.pos, self.mass*20, Charge.NEGATIVE, (0, 0, 255)) else: self.graphicalObject = GraphicalParticle(self.pos, self.mass*20, Charge.POSITIVE, (255, 0, 0))
class Particle: def __init__(self, position, mass, charge, timeInterval): """Takes position as list [x, y], mass, charge (sign indicates positive or negative), and the amount of time that passes between value calculations (the time between frames shown)""" self.moveState = False self.pos = position self.mass = mass self.velocity = [0, 0] self.charge = charge self.timeInterval = timeInterval #setting radius to 20x the mass of particle, can change later if self.charge < 0: self.graphicalObject = GraphicalParticle(self.pos, self.mass*20, Charge.NEGATIVE, (0, 0, 255)) else: self.graphicalObject = GraphicalParticle(self.pos, self.mass*20, Charge.POSITIVE, (255, 0, 0)) def getPos(self): """returns position of particle as list [x, y]""" return [self.pos[0], self.pos[1]] def getMass(self): """returns mass of particle""" return self.mass def getVelocity(self): """return velocity of partice as list [x component, y component]""" return [self.velocity[0], self.velocity[1]] def getCharge(self): """returns charge of particle""" return self.charge @staticmethod def sinatan(x): """Internally used function, returns sine of the arc tangent of the parameter""" return x/math.sqrt((x**2)+1) @staticmethod def cosatan(x): """Internally used function, returns cosine of the arc tangent of the parameter""" return 1 / math.sqrt((x ** 2) + 1) @staticmethod def distance(pos1, pos2): """Internally used function, takes 2 position tuples (x, y) and returns the distance between them""" return ((pos1[0]-pos2[0])**2 + (pos1[1]-pos2[1])**2)**0.5 @staticmethod def arcTanWithChecks(x, y): """Performs the arctangent function on the given fraction (y/x)and handles division by zero""" if x == 0 and y > 0: return math.pi / 2 elif x == 0 and y < 0: return 3 * math.pi / 4 elif x == 0 and y == 0: return 0 else: return math.atan(y/x) @classmethod def crossProduct(cls, vec1, vec2): """Internally used function, takes 2 2-D vectors as tuples and returns the magnitude (with sign) of the resulting cross product""" theta1 = cls.arcTanWithChecks(vec1[0], vec1[1]) theta2 = cls.arcTanWithChecks(vec2[0], vec2[1]) mag1 = cls.distance((0, 0), vec1) mag2 = cls.distance((0,0), vec2) return math.sin(theta1-theta2)*mag1*mag2 def calculateNetMagneticFieldForce(self, particleList): """Internally used method, returns force due to magnetic field effects as tuple (x component, y component)""" netMagField = 0 for p in particleList: if not(p is self): displacementVec = (p.getPos()[0] - self.pos[0], p.getPos()[1] - self.pos[1]) cross = self.crossProduct(p.getVelocity(), displacementVec) distance = self.distance((0, 0), displacementVec) netMagField += (10**-7) * p.getCharge() * cross/distance magnitudeV = self.distance((0, 0), self.velocity) magnitudeF = magnitudeV * netMagField #subtract pi/2 from angle of v to get angle of f angleV = self.arcTanWithChecks(self.velocity[0], self.velocity[1]) angleF = angleV - math.pi/2 return magnitudeF*math.cos(angleF), magnitudeF*math.sin(angleF) def calculateNetCoulombsLawForce(self, particleList): """Internally used method, returns force due to electric interaction with other charged particles as tuple (x component, y component)""" force = [0, 0] for p in particleList: if not(p is self): magnitude = 8.99*(10**9) * self.charge * p.getCharge() / (self.distance(self.pos, p.getPos())**2) #special case so that we don't get division by zero if self.pos[0] - p.getPos()[0] == 0: force[0] += 0 force[1] += magnitude else: angleSlope = (self.pos[1]-p.getPos()[1])/(self.pos[0]-p.getPos()[0]) force[0] += self.cosatan(angleSlope)*magnitude * math.copysign(1.0, self.pos[0]-p.getPos()[0]) force[1] += self.sinatan(angleSlope)*magnitude * math.copysign(1.0, self.pos[0]-p.getPos()[0]) return force[0], force[1] def isInside(self, staticField): """Internally used method that checks if particle is inside a given electric field""" if self.pos[0] > staticField.topLeft[0] and self.pos[0] < staticField.bottomRight[0]: if self.pos[1] > staticField.topLeft[1] and self.pos[1] < staticField.bottomRight[1]: return True return False def calculateNetElectricFieldForce(self, staticFieldList): """Internally used method, returns force due to influence of static electric field on particle as tuple (x component, y component)""" force = [0, 0] for ef in staticFieldList: if self.isInside(ef): magnitude = self.charge * ef.getStrength() force[0] += magnitude*math.cos(ef.getDirection()) force[1] += magnitude*math.sin(ef.getDirection()) return force[0], -force[1] def calculateDisplacement(self, particleList, staticFieldList): """takes list of other particles and static fields in the system, updates internal dx and dy variables""" if self.moveState: self.newVelocity = (0, 0) self.dx = 0 self.dy = 0 else: mff = self.calculateNetMagneticFieldForce(particleList) clf = self.calculateNetCoulombsLawForce(particleList) eff = self.calculateNetElectricFieldForce(staticFieldList) acceleration = ((mff[0]+clf[0]+eff[0])/self.mass, (mff[1]+clf[1]+eff[1])/self.mass) #change in velocity is acceleration*time self.newVelocity = (self.velocity[0] + acceleration[0]*self.timeInterval, self.velocity[1] + acceleration[1]*self.timeInterval) self.dx = self.velocity[0]*self.timeInterval + 0.5*acceleration[0]*self.timeInterval self.dy = self.velocity[1]*self.timeInterval + 0.5*acceleration[1]*self.timeInterval def finalizeValues(self): """Indicates to particle object that all other particle object calculations are done, so that internal values can be updated and used for rendering""" self.pos = [self.pos[0] + self.dx, self.pos[1] + self.dy] self.velocity = self.newVelocity self.graphicalObject.update(self.pos, self.mass*20, Charge.NEGATIVE if self.charge < 0 else Charge.POSITIVE, (0, 0, 255) if self.charge < 0 else (255, 0, 0)) def draw(self, screen): """Draws objects using GraphicalParticle""" self.graphicalObject.draw(screen)
