# problem with exam task for college

S

#### stefaang

Hi,

I only skimmed through the code, but I think your problem resides at the "while True" in your brandstofmeter update(). This function never stops..

J

#### jeltedeproft

this is what i have right now, it tells me i can't multiply a vector with a vector, i have to find a way to multiply the speed with the updated angle (=hoek in dutch)

code :

from visual import *
import time
import math
import random

class lunar_lander(object):
def __init__(self):
scene.title = 'mini star wars'
scene.width = 375
scene.height = 550
scene.center = (0,0)
self.pos = (0,0)
self.axis = 0
self.brandstofmeter = brandstofmeter()
self.ruimteschip = ruimteschip()
self.view = game_view(self)

def play(self):
t=0
dt=0.01
while t<999999999:
time.sleep(0.01)
self.brandstofmeter.update
self.ruimteschip.update(dt)
t = t + dt

class game_view(object):
def __init__(self,owner):
autoscale=True
box(pos=( 0, -375, 0), length=500, height=5, width=0, color = color.white)
box(pos=(0,375, 0), length=500, height=5, width=0, color = color.white)
box(pos=(-250,0, 0), length=5, height=750, width=0, color = color.white)
box(pos=(250,0, 0), length=5, height=750, width=0, color = color.white)

maan = curve(pos=[(-250,-353),(-240,-341),(-210,-354),(-199.5,-374)],color=color.red)
maana = curve(pos=[(-199.5,-374),(-166,-374)],color=color.green)
maanb = curve(pos=[(-166,-374),(-140,-357),(-80,-319),(-40,-361),(0,-321),(40,-329),(80,-347)],color=color.red)
maanc = curve(pos=[(80,-347),(140,-347)],color=color.green)
maand = curve(pos=[(140,-347),(162,-337),(189.5,-365),(210,-355),(240,-372),(250,-338)],color=color.red)

for i in random.sample(range (-250,250),20):
for j in random.sample(range (-375,375),20):
sterren = points(pos = [i,j,0],size = 2, color=color.white)

class brandstofmeter(object):
def __init__(self):
self.size = (25,45)
axis = 0
self.pos = (220,345)
self.view = brandstofmeter_view(self)

def update(self):
while True:
if scene.kb.keys:
s = scene.kb.getkey()
if (s == 'up'):
self.view.update(self)

class brandstofmeter_view(object):
def __init__(self,owner):
self.owner = owner
meter = box(pos = owner.pos,size = owner.size,color = color.green)

def update (self,owner):
self.size = self.size - (0,0.45)

class ruimteschip(object):
def __init__(self):
self.pos = vector(0,330)
self.axis = (1,0,0)
self.view = ruimteschip_view(self)
self.vlam = self.view.vlam
self.frame = self.view.frame
self.hoek = pi / 2

def update(self,dt):
zwaartekracht = vector(0,-2,0)
self.gas = vector(0,10,0)
self.acceleration = zwaartekracht
self.axis = (1,0,0)
if scene.kb.keys:
s = scene.kb.getkey()
if (s == "up"):
self.acceleration =+ self.gas * vector(math.cos(self.hoek),math.sin(self.hoek))
if (s == "left"):
self.hoek =+ pi/12
if (s == "right") :
self.hoek =- pi/12

self.pos = self.pos + self.acceleration
if self.pos.x > 250:
self.pos.x = -250
if self.pos.x < -250:
self.pos.x = 250

if self.acceleration != (0,-2,0):
self.vlam.visible = True
else :
self.vlam.visible = False
self.view.update(self)

class ruimteschip_view(object):
def __init__(self,owner):
self.owner = owner
self.frame = frame(pos = owner.pos,axis = owner.axis)
self.motor = curve(frame = self.frame,pos=[(0,24.0),(22.0,24.0),(22.0,39.0),(-22.0,39.0),(-22,24),(0,24)])
self.capsule = curve(frame = self.frame,color = color.blue ,pos=[(0,39),(-3,39),(-9,44),(-12,46),(-18,48),(-22,50),(-18,52),(-12,54),(-9,56),(-3,61),(0,61),(3,59),(9,56),(12,54),(18,52),(22,50),(18,48),(12,46),(9,44),(3,39),(0,39)])
self.poota = curve(frame = self.frame,pos = [(-18,24),(-20,24),(-20,0),(-18,0),(-18,24)])
self.pootb = curve(frame = self.frame,pos = [(18,24),(20,24),(20,0),(18,0),(18,24)])
self.vlam = curve(frame = self.frame,color = color.orange , visible=false,pos = [(0,24.0),(-9.0,14.0),(0,-5.0),(9,14.0),(0,24.0)])

def update(self,owner):
self.frame.axis = owner.axis
self.frame.pos = owner.pos

D

#### Dennis Lee Bieber

this is what i have right now, it tells me i can't multiply a vector with a vector, i have to find a way to multiply the speed with the updated angle (=hoek in dutch)

It's a trite saying but:

How would you perform this vector multiplication by hand? Write down
the steps... Now convert those steps into Python code.

using NumPy vector types which should support the needed
multiplications.
import numpy
a = numpy.array( (2.78, 3.14, 1958) )
b = numpy.array( (1.5, 2.0, 1.0) )

a*b array([ 4.17, 6.28, 1958. ])
a.dot(b) 1968.45

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