Problems making pygame target image (scope) move with arrow keys

Question

When we run our pygame's code, our target scope image will NOT move, but our do robots generate. We are trying to use our arrow keys to move them and I included all of our code.

Commented out under our newest trial code for moving are two other things we tried.

import pygame, sys  
from graphics import *  
import time  
import random  

pygame.init()  

level=1  
bg = pygame.image.load('bg.png')  
bg_width = 800  
pygame.display.set_caption('Robot Apocalypse')  
surfacew = 1054  
surfacel = 562  
surface = pygame.display.set_mode((surfacew,surfacel))  
black = (0, 0, 0)  
score = 0  
#player_health = 99  
alive=True  

targetImg = pygame.image.load('target.png')  
targetImg = pygame.transform.scale(targetImg, (40, 40))  
targetxy = targetImg.get_rect()  
targetx = targetxy[0]  
targety = targetxy[1]  

def move_target(targetImg):  
    pygame.event.clear()  
    while alive == True:  
        keys_pressed = pygame.key.get_pressed()  
        if keys_pressed[pygame.K_LEFT]:  
            targetx -= 5  
        if keys_pressed[pygame.K_RIGHT]:  
            targetx += 5  
        if keys_pressed[pygame.K_UP]:  
            targety -= 5  
        if keys_pressed[pygame.K_DOWN]:  
            targety += 5  
        pygame.display.update()  
    # pygame.event.clear()  
    # for event in pygame.event.get():  
    #     if event.type ==KEYDOWN:  
    #         if event.key == K_LEFT:  
    #             direction = MOVE_LEFT  
    #         elif event.key == K_RIGHT:  
    #             direction = MOVE_RIGHT  
    #     elif event.type == KEYUP:  
    #         if event.key == K_LEFT:  
    #             direction = 0  
    #         elif event.key == K_RIGHT:  
    #             direction = 0  
    # if(direction == MOVE_LEFT):  
    #     targetx-=10  
    # elif(direction == MOVE_RIGHT):  
    #     targetx+=10  

    # for event in pygame.event.get():  
    #     print(event)  
    #     if event.type==QUIT:  
    #          pygame.quit()  
    #          sys.exit()  
    #     if event.type == KEYDOWN:  
    #         if event.key == K_LEFT:  
    #             targetx-=5  
    #         elif event.key == K_RIGHT:  
    #             targetx+=5  
    #         elif event.key == K_UP:  
    #             targety-=5  
    #         elif event.key == K_DOWN:  
    #             targety+=5  
    #     pygame.display.update()  

def shoot():  
    #while True:  
    shot = False  

    pos = (targetx, targety)  
    t = screen.blit(robot, (64,64))  
    if t.collidepoint(pos):  
        shot = True  
    return shot  

def generate_robot(x,y):  
    #while displayrobot == True  
    robot=pygame.draw.rect(surface, (255,0,0), (x,y,64,64), 0)  
    for event in pygame.event.get():  
        if event.type == pygame.KEYDOWN:  
            if event.key == pygame.K_SPACE:  
                shoot()  
                if shot == True:  
                    displayrobot = False  
                    cover = surface.blit(bg, (x,y))  
                    pygame.display.update()  
    return x, y  

    #if shot == True:  

def die():  
    message("YOU DIED")  
    pygame.display.update()  

def win(level):  
    level+=1  

def text_objects(text, font):  
    textSurface = font.render(text, True, black)  
    return textSurface, textSurface.get_rect()  

def message(text):  
    largeText = pygame.font.Font('freesansbold.ttf',60)  
    TextSurf, TextRect = text_objects(text, largeText)  
    TextRect.center = ((surfacew/6),(surfacel/2))  
    surface.blit(TextSurf, TextRect)  
    pygame.display.update()  
    time.sleep(2)  

def main(alive):  
    #displayrobot = True:  
    robot=0  
    score=0  
    surface.fill(black)  
    surface.blit(bg, (0,0))  
    message("Level "+ str(level))  
    mouse = pygame.mouse.get_pos()  
    target = surface.blit(targetImg, (mouse))  
    while alive==True:  
        # robot = enemy(64, 64)  
        x=random.randint(40,760)  
        y=random.randint(40,560)  
        generate_robot(x,y)  
        pygame.display.update()  
        robot+=1  
        time.sleep(8/level)  
    if robot>50 and robot>score:  
        alive=False  
    # if pygame.mouse.get_pressed()==True:  
    #     shoot() #maybe??  
        if shot==True:  
            score+=1  
            robot-=1  
        if robot==10/(level/2): #if 10- robots on screen then...  
            die()  
        if score>25*(level/2):  
            win()  
move_target(targetImg)
main(alive)  
pygame.quit()  
quit()

. There are no error messages, but it won't move. We've tried a ton of different things (that aren't included) and looked up a lot of websites so please help us. Thanks

Your code doesn't move anything; all it does is to change a pair of local variables. You've never associated those with a game object. If fact, you don't *have* any game objects, and nothing to call this function. What flow hanve you designed in which this moves things? — Prune, Jul 19 '19 at 21:40
Instructions for editing your post are in the intro tour. Look for the "edit" button at the bottom of your posting. — Prune, Jul 19 '19 at 21:50
to move object you have change `x,y`, clean screen, `blit()` image in new place and send it on monitor (`display.update()` or `display.flip()`) but you only change `x,y` and run `display.update()` — furas, Jul 19 '19 at 22:11
instead of using `targetx`, `targety` you should use `targetxy.x` , `targetxy.y` because this way you keep position in `Rect` which you can still use to blit image but also to check collision. — furas, Jul 19 '19 at 22:18
commented code in `move_target()` probably has wrong indentions and it was executed after `while alive` but it should be inside `while alive`. The same problem can be with code after `while alive` in `main()` — furas, Jul 19 '19 at 22:21

score 1 · Answer 1 · answered Jul 19 '19 at 22:36

It looks like my original functional comment is still "in force": your code doesn't move any game object.

targetxy = targetImg.get_rect()  
targetx = targetxy[0]
targety = targetxy[1]

At this point, targetxy is a reference to the bounding rectangle for your game object. targetx and targety are copies of the values of the rect position.

def move_target(targetImg):  
    pygame.event.clear()  
    while alive == True:  
        keys_pressed = pygame.key.get_pressed()  
        if keys_pressed[pygame.K_LEFT]:  
            targetx -= 5
        ...

You've change the local copy of the x-coordinate. This does not affect the position of targetImg. You need to change the object's attributes, such as

            targetxy.x -= 5

After this, you need to update the game screen.

score 1 · Accepted Answer · answered Jul 19 '19 at 22:36

To move object you have to not only change x,y and update screen (send buffer to video card which will display it) but also clean buffer, draw image in new place in buffer (blit()).

This code shows only working move_target. I skiped rest of code.

I keep position in target_rect which is pygame.Rect. You can use it to blit(img,rect) but later you can also use to check collision rect.colliderect(other_rect)

import pygame

# --- constants --- (UPPER_CASE_NAMES)

BLACK = (0, 0, 0)  

SURFACE_WIDTH = 1054  
SURFACE_HEIGHT = 562  

# --- functions --- (lower_case_names)

def move_target(target_img, target_rect):
    alive = True  
    clock = pygame.time.Clock()
    while alive:

        # --- events ---

        for event in pygame.event.get():  
            if event.type == pygame.QUIT:  
                alive = False
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    alive = False

        # --- updates/changes ---

        keys_pressed = pygame.key.get_pressed()  

        if keys_pressed[pygame.K_LEFT]:  
            target_rect.x -= 5  
        if keys_pressed[pygame.K_RIGHT]:  
            target_rect.x += 5  
        if keys_pressed[pygame.K_UP]:  
            target_rect.y -= 5  
        if keys_pressed[pygame.K_DOWN]:  
            target_rect.y += 5

        # --- draws ---

        surface.fill(BLACK)
        surface.blit(target_img, target_rect)
        pygame.display.update()

        # the same game's speed on all computers = 60 FPS
        clock.tick(60)

# --- main --- (lower_case_names)

pygame.init()  

pygame.display.set_caption('Robot Apocalypse')  
surface = pygame.display.set_mode((SURFACE_WIDTH, SURFACE_HEIGHT))  

target_img = pygame.image.load('target.png')  
target_img = pygame.transform.scale(target_img, (40, 40))  
target_rect = target_img.get_rect()  

move_target(target_img, target_rect)

pygame.quit()

Problems making pygame target image (scope) move with arrow keys

2 Answers2