Can someone help me find the error in my python program?

Question

Hi here is my error and my python program I have been stuck on this for a week and desperately need some help If anyone knows what the error is and how to solve it, please comment down below! I will be grateful for any help! This is copied from a python tutorial and it is not working

import pygame
import sys
import math
pygame.init()


def cropSurface(newWidth,newHeight,cropWidth,cropHeight,
                image):
    newSurf=pygame.Surface((newWidth,newHeight),
                          pygame.SRCALPHA,32)
    newSurf.blit(image,(0,0),(cropWidth,cropHeight,
                              newWidth,newHeight))
    return newSurf

def movePlayer(direction,radius,absRot):
    yChange=5
    deltaTheta=int(90/(radius/yChange))
    if direction=="Left":
        deltaTheta*=-1

    finalRot=(absRot+deltaTheta)*math.pi/180

    Hypotenuse=(radius*math.sin(finalRot)/
                (math.sin((math.pi-finalRot)/2)))

    newX=Hypotenuse*math.cos(math.pi/2-(math.pi-finalRot)/2)
    newY=Hypotenuse*math.sin(math.pi/2-(math.pi-finalRot)/2)

    return newX,newY,absRot+deltaTheta
def updateFrameImages(showFoot=False):
    global screen,grassImage,goalLeft,goalMiddle,goalRight
    global ball,player,goalStart,ballX,ballY
    global playerX,playerY
    screen.blit(grassImage,(0,0))
    screen.blit(goalLeft,(goalStart,0))
    screen.blit(goalMiddle,(goalStart+
                        goalLeft.get_rect().width,
                        0))
    screen.blit(goalRight,(goalStart+
                       goalLeft.get_rect().width+
                       goalMiddle.get_rect().width,
                       0))
    if showFoot:
        global foot,footX,footY
        screen.blit(foot,(footX-foot.get_rect().width/2,
                          footY-foot.get_rect().height/2))
        
        screen.blit(ball,(ballX-ball.get_rect().width/2,
                      ballY-ball.get_rect().height/2))
            
        screen.blit(player,(playerX-player.get_rect().width/2,
                        playerY-player.get_rect().height/2))
width=900
height=700
screenDim=(width,height)

screen=pygame.display.set_mode(screenDim)

pygame.display.set_caption("my second game")

grassImage=pygame.image.load("23.2_-_grass.png").convert()
grassImage=pygame.transform.scale(grassImage,(width,height))
screen.blit(grassImage,(0,0))


rescale=3
player=pygame.image.load("24.4_-_characterBody.png").convert_alpha()
playerWidth=player.get_rect().width
playerHeight=player.get_rect().height
player=pygame.transform.scale(player,(playerWidth*rescale,playerHeight*rescale))
player=pygame.transform.rotate(player,90)
playerStart=player
currentRotation=0
playerStart=player
currentRotation=0
foot=pygame.image.load("24.3_-_characterFoot.png").convert_alpha()
footWidth=foot.get_rect().width
footHeight=foot.get_rect().height
foot=pygame.transform.scale(foot,(footWidth*rescale,footHeight*rescale))
foot=pygame.transform.rotate(foot,90)
footStart=foot

rescaleBall=2
ball=pygame.image.load("24.2_-_ball.png").convert_alpha()
ballWidth=ball.get_rect().width
ballHeight=ball.get_rect().height
ball=pygame.transform.scale(ball,(ballWidth*rescaleBall,ballHeight*rescaleBall))



goalLeft=pygame.image.load("25.2_-_goalLeft.png").convert_alpha()
goalLeft=pygame.transform.scale(goalLeft,(250,270))
goalLeftWidth=goalLeft.get_rect().width
goalLeftHeight=goalLeft.get_rect().height
adjust=12
goalLeft=cropSurface(goalLeftWidth/2+adjust,
                     goalLeftHeight/2+adjust,
                     goalLeftWidth/2-adjust,
                     goalLeftHeight/2-adjust,
                goalLeft)


goalMiddle=pygame.image.load("26.2_-_goalMiddle.png").convert()
goalMiddle=pygame.transform.scale(goalMiddle,(250,270))
goalMiddleWidth=goalMiddle.get_rect().width
goalMiddleHeight=goalMiddle.get_rect().height
goalMiddle=cropSurface(goalMiddleWidth,
                       goalMiddleHeight/2+adjust,
                       0,
                       goalMiddleHeight/2-adjust,
                       goalMiddle)


goalRight=pygame.image.load("26.3_-_goalRight.png").convert_alpha()
goalRight=pygame.transform.scale(goalRight,(250,270))
goalRightWidth=goalRight.get_rect().width
goalRightHeight=goalRight.get_rect().height

goalRight=cropSurface(goalRightWidth/2+adjust,goalRightHeight/2+adjust,0,goalRightHeight/2-adjust,goalRight)


goalStart=(width-goalLeft.get_rect().width-
           goalMiddle.get_rect().width-
           goalRight.get_rect().width)/2

screen.blit(goalLeft,(goalStart,0))
screen.blit(goalMiddle,(goalStart+goalLeft.get_rect().width,0))
screen.blit(goalRight,(goalStart+goalLeft.get_rect().width+goalMiddle.get_rect().width,0))


playerX=width/2
playerY=530

playerXOriginal=playerX
playerYOriginal=playerY
#screen.blit(foot,(0,0))
screen.blit(player,(playerX-player.get_rect().width/2,
                    playerY-player.get_rect().height/2))
ballX=width/2
ballY=450

radius=playerY-ballY
screen.blit(ball,(ballX-ball.get_rect().width/2,
                  ballY-ball.get_rect().height/2))

frame=pygame.time.Clock()
finished = False
while finished ==False:
    #a;slkdjf;alskdjf;aslkdjf;a;dlkfj
    for event in pygame.event.get():
        #a;fjallkdjfaa;lakjdf;ala;sdkfja;
        if event.type==pygame.QUIT:
            finished=True
            pygame.quit()
            sys.exit()

    pressedKeys=pygame.key.get_pressed()
    print(pygame.K_LEFT)
    
    if pressedKeys[pygame.K_LEFT]==1:
        if currentRotation>-90:
            changeX,changeY,currentRotation=movePlayer("Left",radius,currentRotation)
            player=pygame.transform.rotate(playerStart,currentRotation)
            playerX=playerXOriginal+changeX
            playerY=playerYOriginal-changeY
        
    elif pressedKeys[pygame.K_RIGHT]==1:
        if currentRotation<90:
            changeX,changeY,currentRotation=movePlayer("Right",radius,currentRotation)
            player=pygame.transform.rotate(playerStart,currentRotation)
            playerX=playerXOriginal+changeX
            playerY=playerYOriginal-changeY
        
    elif pressedKeys[pygame.K_SPACE]==1:
        xMove=(playerX-ballX)/10
        yMove=(playerY-ballY)/10
        normMove=1/math.sqrt(xMove**2+yMove**2)
        distanceToShoulder=20
        shoulderAngle=currentRotation*math.pi/180
        for i in range(3):
            playerX-=xMove
            playerY-=yMove
            updateFrameImages()
            pygame.display.flip()
            frame.tick(30)
        footX=(playerX+distanceToShoulder*math.cos(shoulderAngle)-25*xMove*normMove)
        footY=(playerY-distanceToShoulder*math.sin(shoulderAngle)-25*yMove*normMove)
        foot=pygame.transform.rotate(footStart,currentrotation)
        updateFrameImages()
    #wwwwwwwwww
    updateFrameImages(True)
    pygame.display.flip()
            
    screen.blit(player,(playerX-player.get_rect().width/2,
                        playerY-player.get_rect().height/2))
    pygame.display.flip()
    frame.tick(30)

and here is my error

Traceback (most recent call last):
  File "C:\Users\Divija\Downloads\Udemy Master Python Interactively With PyGame Ultimate Bootcamp_git.ir\5_-_Files_And_Images\py.py", line 191, in <module>
    updateFrameImages(True)
  File "C:\Users\Divija\Downloads\Udemy Master Python Interactively With PyGame Ultimate Bootcamp_git.ir\5_-_Files_And_Images\py.py", line 45, in updateFrameImages
    screen.blit(foot,(footX-foot.get_rect().width/2,
NameError: name 'footX' is not defined

        

        

Answer 1

According to the given code and error message, the variable "footX" has been referred as global variable but it has not been defined anywhere globally in your code.

This piece of code might make it clear why you are getting this error

footX = "some value" # you get error if this line is commented out


def my_func():
    global footX
    print("here footX is accessed as a global variable with value {}".format(footX))


my_func()

Also I have noticed that the footX variable in your code is getting declared in a if else block and the function using this variable is called later.

So it might be the case that the particular elif block ( which create footX variable ) is not executed and this gives error in UpdateFrameImages function.

Possible Solution:

The UpdateFrameImages function uses footX only when showFoot=True . So initially, showFoot argument can be set to False when footX is not defined.

When footX is defined ie in the elif block, then set showFoot = True when calling UpdateFrameImages .

NOTE: Also I have changed currentrotation to currentRotation since currentrotation wasn't defined anywhere.

I have made these changes in the while loop as follows, just replace it with your while loop:

while finished ==False:
    #a;slkdjf;alskdjf;aslkdjf;a;dlkfj
    for event in pygame.event.get():
        #a;fjallkdjfaa;lakjdf;ala;sdkfja;
        if event.type==pygame.QUIT:
            finished=True
            pygame.quit()
            sys.exit()

    pressedKeys=pygame.key.get_pressed()
    print(pygame.K_LEFT)
    
    if pressedKeys[pygame.K_LEFT]==1:
        if currentRotation>-90:
            changeX,changeY,currentRotation=movePlayer("Left",radius,currentRotation)
            player=pygame.transform.rotate(playerStart,currentRotation)
            playerX=playerXOriginal+changeX
            playerY=playerYOriginal-changeY
        
    elif pressedKeys[pygame.K_RIGHT]==1:
        if currentRotation<90:
            changeX,changeY,currentRotation=movePlayer("Right",radius,currentRotation)
            player=pygame.transform.rotate(playerStart,currentRotation)
            playerX=playerXOriginal+changeX
            playerY=playerYOriginal-changeY
        
    elif pressedKeys[pygame.K_SPACE]==1:
        xMove=(playerX-ballX)/10
        yMove=(playerY-ballY)/10
        normMove=1/math.sqrt(xMove**2+yMove**2)
        distanceToShoulder=20
        shoulderAngle=currentRotation*math.pi/180
        for i in range(3):
            playerX-=xMove
            playerY-=yMove
            updateFrameImages()
            pygame.display.flip()
            frame.tick(30)
        footX=(playerX+distanceToShoulder*math.cos(shoulderAngle)-25*xMove*normMove)
        footY=(playerY-distanceToShoulder*math.sin(shoulderAngle)-25*yMove*normMove)
        foot=pygame.transform.rotate(footStart,currentRotation) #changed 'currentotation' to 'currentRotation'
        updateFrameImages(True) # true beacuse now footX is defined
    #wwwwwwwwww
    updateFrameImages(False) #false since footX not defined initially
    pygame.display.flip()
            
    screen.blit(player,(playerX-player.get_rect().width/2,
                        playerY-player.get_rect().height/2))
    pygame.display.flip()
    frame.tick(30)