PyGame sprite assistance

Question

I've basically just started developing with PyGame and I am having trouble with the whole Sprite concept. I have been looking every where for guides on how to use it, I just can't seem to find any. I would like to know the basic concept of how it all works. This is the code I have been working on:

import pygame, sys, os, time
from pygame.locals import *

windowWidth = 320
windowHeight = 640
halfWidth = int(windowWidth / 2)
halfHeight = int(windowHeight / 2)

#main blocks width and height (32x32)
blockSize = 32

#rgb
red = [255,000,000]
green = [000,255,000]
blue = [000,000,255]
black = [000,000,000]
white = [255,255,255]

bgColor = black
playerColor = white
blockColor = green

fps = 60

assert windowWidth % blockSize == 0, "Too much space/not enough space for the ground"
floorAmt = windowWidth/blockSize
print floorAmt

floorY = windowHeight-blockSize
print floorY

floor = pygame.sprite.Group()


def main():

    global fpsClock, displayScreen

    inAir = False

    upVel = 0
    downVel = 0
    leftVel = 0
    rightVel = 0

    fpsClock = pygame.time.Clock()
    displayScreen = pygame.display.set_mode((windowWidth, windowHeight))
    pygame.display.set_caption("Jump Test")

    grass = pygame.image.load("grass.png")
    grass = grass.convert_alpha()
    grassRadius = blockSize

    floorDraw(blockSize, floorAmt, floorY, grass)

    while True:
        fpsClock.tick(fps)

        for event in pygame.event.get():
            if event.type == QUIT or (event.type == KEYDOWN and event.key == K_ESCAPE):
                pygame.quit()
                sys.exit()
                raise SystemExit, "Exit"

        displayScreen.fill(black)
        floorDraw(blockSize, floorAmt, floorY)

        pygame.display.flip()
        pygame.display.update()
        fpsClock.tick(fps)

def floorDraw(blockSize, floorAmt, floorY, grass):
    for i in range(floorAmt):
        floorX = i*blockSize
        grassRect = (floorX, floorY, blockSize, blockSize)
        floor.add(grass)
        displayScreen.blit(grass, grassRect)

        v
if __name__ == "__main__":
    main()

basically I just want to know how to make these grass blocks into sprites in a group, so that when I add my player (also a sprite) I can determine whether or not he is in the air or not through the collision system. Can someone please explain to me how I would do this. All I am looking for is basically a kick starter because some of the documentation is quite bad in my opinion as it doesn't completely tell you how to use it. Any help is greatly appreciated :)

Answer 1

Although it may be a bad design choice, the Sprite object is meant to be inherited and be managed as a group.

You did right by creating the floor as Group and adding each grass to it.

But what I would suggest is to inherit the Sprite object to class you created yourself. Usually my Entities starts with the following:

class Entity(pygame.sprite.Sprite):
    def __init__(self, x, y, width=1, height=1):
        pygame.sprite.Sprite.__init__(self)
        self.rect = pygame.Rect((x, y), (width, height))
        ...

It is an Sprite, but it contains the Rect object that you will want to use for a lot of reasons, like Bounding Box collisions and for moving your entity. Then, you can simple call

pygame.sprite.spritecollide(sprite, group, dokill, collided = None)

and have a list of Sprites that collide, so you can can manage them. More info on:

http://www.pygame.org/docs/ref/sprite.html#pygame.sprite.spritecollide

In fact, Pygame have lots of collision detection methods that do the same thing: check for a intersection between two Rect objects.

You can look thought this book, it may be useful: http://inventwithpython.com/ There are also some tutorials over here and there, and the mail-list.

Hope that helps!