How to dynamically generate shapes in Pygame?

user_9982005 0
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I'm trying to generate multiple rectangles which translate across the screen with varying distance of separation between any two consecutive rectangles.

Here's the snippet of the code-

win = pygame.display.set_mode((500, 500)) #canvas size is 500x500

width = 40
height = 60
x = 500 - width
y = 500 - height
vel = 5

state = True
while(state):
   pygame.time.delay(50)
   x -= vel
   pygame.draw.rect(win, (0, 0, 255), (x, y, width, height))
   pygame.display.update()

#I have not included the pygame exit code

Now, how do I go about this, without making the rectangles disappear everytime I try to generate a new one?

pygame python
2 Answers

Create a list of rectangles:

rect_list = []

When you want to add a new rectangle, the append an new pygame.Rect object to the list:

rect_list.append(pygame.Rect(x, y, width, height))

Change the location of the rectangle and draw the rectangles in a loop, in the main application loop:

state = True
while state:
    # [...]

    for rect_obj in rect_list:
        rect_obj.x -= vel
        pygame.draw.rect(win, (0, 0, 255), rect_obj)

    # [...]
user_55777650

This answer is derived off Rabbid76's answer, but with a slight modification that allows each individual rect to have it's own vel speed and color:

class rectangle:
# You can add as many new values as you like, just be wary about changing the other magic methods
    def __init__(top, left, width, height, vel, color=(0, 0, 255)):
        self.vel = vel
        self.pos = (top, left)
        self.size = (width, height)
        self.rect = self.pos + self.size

    def __iter__(self):
        return self.rect

    def __getitem__(self, key):
        if type(key)!=int:
            raise TypeError('invalid key!')
        return self.rect[key]

    def __len__(self):
        return len(self.rect)

    def __reversed__(self):
        return reversed(self.rect)

    def update_rect(self): # This should be called every time you make an adjustment to pos or size
        self.rect = self.pos+self.size

    def move(self, x, y):
        self.pos[0] += x
        self.pos[1] += y
        self.update_rect

    def resize(self, width, height):
        self.size = (width, height)
        self.update_rect

Now, you store a list of instances:

rect_list = []
rect_list.append(rectangle(top, left, width, height, vel, color)) # You can call this as many times as you want

of these classes instead of a list of pygame.Rects, and when it comes time to draw it, the magic methods will come into play, and magically make it a pygame.Rect object:

for rect in rect_list:
    rect.move(x=-rect.vel, y=0) # Move it negative x
    pygame.draw.rect(win, rect.color, pygame.Rect(rect)) # Draw it.
user_126921820
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