我有一个重力矢量（形式为[r，theta]），我将其添加到我的球的速度矢量中。由于某种原因，球在弹跳后不会返回到相同的高度，而是偶尔慢慢地失去高度。我猜测有一些舍入错误或我正在使用的计算中的某些内容，但我不能隔离这个问题。
这是我的代码。你需要文件和pygame来运行它。对不起，如果有点混乱。如果你愿意，我可以发表更多评论。
每当球达到最大高度时我都会添加一个标记，所以你们就是我的意思。我希望每次弹跳时球都能恢复到完全相同的高度。
我拿了一些不必要的代码。完整的程序在pastebin链接下。
https://pastebin.com/FyejMCmg - PhysicsSim
import pygame, sys, math, tools, random, time
from pygame.locals import *
clock = pygame.time.Clock()
lines = []
class Particle:
def __init__(self,screen,colour, mass, loc, vel):
self.screen = screen
self.colour = colour
self.mass = mass
self.x = loc[0]
self.y = loc[1]
self.location = self.x,self.y
self.speed = vel[0]
self.angle = vel[1]
def update(self):
global lines
# add gravity
self.speed,self.angle = tools.add_vectors2([self.speed,self.angle], tools.GRAVITY)
# update position
dt = clock.tick(60)
self.x += self.speed * tools.SCALE * math.cos(self.angle) * dt
self.y -= self.speed * tools.SCALE * math.sin(self.angle) * dt
self.location = int(self.x),int(self.y)
# border checking
do = False
n=[]
if ((self.y+self.mass) > tools.SCREEN_HEIGHT):
self.y = tools.SCREEN_HEIGHT-self.mass
n = [0,1]
do = True
# adds position to array so max height so max height can be recorded
if (self.speed==0):
lines.append([self.screen, self.location, self.mass])
# bounce
if do:
#init, convert everything to cartesian
v = tools.polarToCartesian([self.speed, self.angle])
#final -> initial minus twice the projection onto n, where n is the normal to the surface
a = tools.scalarP(2*abs(tools.dotP(v,n)),n) #vector to be added to v
v = tools.add_vectors(v,a)
self.angle = tools.cartesianToPolar(v)[1] # does not set magnitude
# drawing
pygame.draw.circle(self.screen, self.colour, self.location, self.mass, 0)
# draws max height line
def draw_line(l):
screen = l[0]
location = l[1]
radius = l[2]
pygame.draw.line(screen, tools.BLACK, [location[0] + 15, location[1]-radius],[location[0] - 15, location[1]-radius])
def main():
pygame.init()
DISPLAY = pygame.display.set_mode(tools.SCREEN_SIZE,0,32)
DISPLAY.fill(tools.WHITE)
particles = []
particles.append(Particle(DISPLAY, tools.GREEN, 10, [100,100], [0,0]))
done = False
while not done:
global lines
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
DISPLAY.fill(tools.WHITE)
for i in particles:
i.update()
for l in lines:
draw_line(l)
pygame.display.update()
main()
https://pastebin.com/Epgqka31 - 工具
import math
#colours
WHITE = (255, 255, 255)
BLUE = ( 0, 0, 255)
GREEN = ( 0, 255, 0)
RED = ( 255, 0, 0)
BLACK = ( 0, 0, 0)
COLOURS = [WHITE,BLUE,GREEN,RED,BLACK]
#screen
SCREEN_SIZE = SCREEN_WIDTH,SCREEN_HEIGHT = 1000,700
#vectors
GRAVITY = [5.0, 3*math.pi/2] # not 9.8 because it seems too high
SCALE = 0.01
# converts polar coordinates to cartesian coordinates in R2
def polarToCartesian(v):
return [v[0]*math.cos(v[1]), v[0]*math.sin(v[1])]
# converts cartesian coordinates to polar coordinates in R2
def cartesianToPolar(v):
return [math.sqrt(v[0]**2 + v[1]**2), math.atan2(v[1],v[0])]
# dots two cartesian vectors in R2
def dotP(v1, v2):
return v1[0]*v2[0] + v1[1]*v2[1]
# multiplies cartesian vector v by scalar s in Rn
def scalarP(s,v):
v_=[]
for i in v:
v_.append(s*i)
return v_
# returns the sum of two cartesian vectors in R2
def add_vectors(v1, v2):
return [v1[0]+v2[0], v1[1]+v2[1]]
# returns the sum of two polar vectors in R2, equations from https://math.stackexchange.com/questions/1365622/adding-two-polar-vectors
def add_vectors2(v1,v2):
r1,r2,t1,t2 = v1[0],v2[0],v1[1],v2[1]
return [math.sqrt(r1**2 + r2**2 + 2*r1*r2*math.cos(t2-t1)), t1 + math.atan2(r2*math.sin(t2 - t1), r1 + r2*math.cos(t2 - t1))]
答案 0 :(得分：6)
您的时间间隔dt = clock.tick(60)不是常数。如果将其更改为dt = 60，程序将按预期运行。
查看Verlet Algorithm并在您的代码中实现它。你走在正确的轨道上了！