Terrain generator in a PyGame game

Question

In my game, there is a terrain generator subsequently resulting in many instances.

I have implemented this code:

for b in blocklist:
 if b.rect.left>=0:
 if b.rect.right<=640:
 screen.blit(b.sprite, b.rect)

It only renders things within the screen (400-500 blocks), but it still runs as if it were rendering all 2000 or so.

Why is it so slow? Does it have anything to do with pygame.display.update() or pygame.display.flip()? Is there even a difference?

Here is the entire code:

#Init stuff
import pygame,random
from pygame.locals import *
from collections import namedtuple
import time, string
pygame.mixer.init(frequency=22050, size=-16, channels=2, buffer=500)
f=open('texdir.txt','r')
texdir=f.read()
f.close()
f=open(texdir+"\\splash.txt",'r')
splash=f.read()
splash=splash.replace('(','')
splash=splash.replace(')','')
splash=splash.split(',')
f.close()
splashlen=len(splash)
chc=random.randint(0,int(splashlen))
splash=splash[chc-1]
f=open(texdir+"//backcolor.txt")
pygame.init()
clock=pygame.time.Clock()
screen=pygame.display.set_mode((640,480))
pygame.display.set_caption("PiBlocks | By Sam Tubb")
max_gravity = 100
blocksel=texdir+"\\dirt.png"
btype='block'
backimg = pygame.image.load(texdir+"\\menu.png").convert()
backimg = pygame.transform.scale(backimg, (640,480))
clsimg = pygame.image.load("clear.bmp").convert()
clsimg = pygame.transform.scale(clsimg, (640,480))
ingame=0
sbtn=pygame.image.load("startbtn.png").convert()
qbtn=pygame.image.load("quitbtn.png").convert()
tbtn=pygame.image.load("texbtn.png").convert()
sbtnrect=sbtn.get_rect()
sbtnrect.x=220
sbtnrect.y=190
qbtnrect=qbtn.get_rect()
qbtnrect.x=220
qbtnrect.y=225
tbtnrect=tbtn.get_rect()
tbtnrect.x=220
tbtnrect.y=260
go=0
gotime=35
select=1
colliding = False
Move = namedtuple('Move', ['up', 'left', 'right'])
player=[]
blocklist=[]
font=pygame.font.Font(None,18)
#set cursor
curs = pygame.image.load(texdir+"\\cursor.png").convert()
curs.set_colorkey((0,255,0))
#set backcolor
COLOR=f.read()
f.close()
COLOR=COLOR.replace('(','')
COLOR=COLOR.replace(')','')
COLOR=COLOR.split(',')
c1=COLOR[0]
c2=COLOR[1]
c3=COLOR[2]
#load sounds
place=pygame.mixer.Sound('sound\\place.wav')
place2=pygame.mixer.Sound('sound\\place2.wav')
place3=pygame.mixer.Sound('sound\\place3.wav')
#set sprites and animation frames
psprite = pygame.image.load(texdir+"\\player\\playr.png").convert()
psprite.set_colorkey((0,255,0))
psprite2 = pygame.image.load(texdir+"\\player\\playr2.png").convert()
psprite2.set_colorkey((0,255,0))
psprite3 = pygame.image.load(texdir+"\\player\\playr3.png").convert()
psprite3.set_colorkey((0,255,0))
anim=1
class Block(object):
 def __init__(self,x,y,sprite,btype):
 if blocksel==texdir+"\\woodslab.png":
 self.btype='slab'
 self.sprite = pygame.image.load(sprite).convert()
 self.rect = self.sprite.get_rect(top=y+16, left=x)
 else:
 self.btype='block'
 self.sprite = pygame.image.load(sprite).convert_alpha()
 self.rect = self.sprite.get_rect(top=y, left=x)
class Player(object):
 sprite=psprite
 def __init__(self, x, y):
 self.rect = self.sprite.get_rect(centery=y, centerx=x)
 # indicates that we are standing on the ground
 # and thus are "allowed" to jump
 self.on_ground = True
 self.xvel = 0
 self.yvel = 0
 self.jump_speed = 7
 self.move_speed = 3
 def update(self, move, blocks):
 # check if we can jump 
 if move.up and self.on_ground:
 self.yvel -= self.jump_speed
 # simple left/right movement
 if move.left:
 self.xvel = -self.move_speed
 if move.right:
 self.xvel = self.move_speed
 # if in the air, fall down
 if not self.on_ground:
 self.yvel += 0.3
 # but not too fast
 if self.yvel > max_gravity: self.yvel = max_gravity
 # if no left/right movement, x speed is 0, of course
 if not (move.left or move.right):
 self.xvel = 0
 # move horizontal, and check for horizontal collisions
 self.rect.left += self.xvel
 self.collide(self.xvel, 0, blocks)
 # move vertically, and check for vertical collisions
 self.rect.top += self.yvel
 self.on_ground = False;
 self.collide(0, self.yvel, blocks)
 def collide(self, xvel, yvel, blocks):
 # all blocks that we collide with
 for block in [blocks[i] for i in self.rect.collidelistall(blocks)]:
 # if xvel is > 0, we know our right side bumped 
 # into the left side of a block etc.
 if xvel > 0:
 self.rect.right = block.rect.left
 if xvel < 0:
 self.rect.left = block.rect.right
 # if yvel > 0, we are falling, so if a collision happpens 
 # we know we hit the ground (remember, we seperated checking for
 # horizontal and vertical collision, so if yvel != 0, xvel is 0)
 if yvel > 0:
 self.rect.bottom = block.rect.top
 self.on_ground = True
 self.yvel = 0
 # if yvel < 0 and a collision occurs, we bumped our head
 # on a block above us
 if yvel < 0: self.rect.top = block.rect.bottom
def get_key():
 while 1:
 event = pygame.event.poll()
 if event.type == KEYDOWN:
 return event.key
 else:
 pass
def display_box(screen, message):
 "Print a message in a box in the middle of the screen"
 fontobject = pygame.font.Font(None,18)
 pygame.draw.rect(screen, (0,0,0),
 ((screen.get_width() / 2) - 100,
 (screen.get_height() / 2) - 10,
 200,20), 0)
 pygame.draw.rect(screen, (255,255,255),
 ((screen.get_width() / 2) - 102,
 (screen.get_height() / 2) - 12,
 204,24), 1)
 if len(message) != 0:
 screen.blit(fontobject.render(message, 1, (255,255,255)),
 ((screen.get_width() / 2) - 100, (screen.get_height() / 2) - 10))
 pygame.display.flip()
def ask(screen, question):
 "ask(screen, question) -> answer"
 pygame.font.init()
 current_string = []
 display_box(screen, question + ": " + string.join(current_string,""))
 while 1:
 inkey = get_key()
 if inkey == K_BACKSPACE:
 current_string = current_string[0:-1]
 elif inkey == K_RETURN:
 break
 elif inkey == K_MINUS:
 current_string.append("_")
 elif inkey <= 127:
 current_string.append(chr(inkey))
 display_box(screen, question + ": " + string.join(current_string,""))
 return string.join(current_string,"")
while True:
 for block in blocklist:
 if any(block.rect.colliderect(b.rect) for b in blocklist if b is not block):
 if b.btype=='slab':
 blocklist.remove(block)
 else:
 blocklist.remove(b)
 if ingame==1:
 screen.fill((int(c1),int(c2),int(c3)))
 mse = pygame.mouse.get_pos()
 key = pygame.key.get_pressed()
 if key[K_a]:
 anim+=1
 if anim==9:
 anim=1
 if key[K_d]:
 anim+=1
 if anim==9:
 anim=1
 if key[K_1]:
 blocksel=texdir+"\\dirt.png"
 btype='block'
 select=1
 if key[K_2]:
 blocksel=texdir+"\\stonetile.png"
 btype='block'
 select=2
 if key[K_3]:
 blocksel=texdir+"\\stone.png"
 btype='block'
 select=3
 if key[K_4]:
 blocksel=texdir+"\\sand.png"
 btype='block'
 select=4
 if key[K_5]:
 blocksel=texdir+"\\woodplank.png"
 btype='block'
 select=5
 if key[K_6]:
 blocksel=texdir+"\\woodslab.png"
 btype='slab'
 select=6
 if key[K_LEFT]:
 try:
 for b in blocklist:
 b.rect.left+=32
 except:
 pass
 try:
 player.rect.left+=32
 except:
 pass
 if key[K_RIGHT]:
 try:
 for b in blocklist:
 b.rect.left-=32
 except:
 pass
 try:
 player.rect.left-=32
 except:
 pass
 if key[K_UP]:
 try:
 for b in blocklist:
 b.rect.top+=32
 except:
 pass
 try:
 player.rect.top+=32
 except:
 pass
 if key[K_DOWN]:
 try:
 for b in blocklist:
 b.rect.top-=32
 except:
 pass
 try:
 player.rect.top-=32
 except:
 pass
 if key[K_ESCAPE]:
 execfile('PiBlocks.pyw')
 for event in pygame.event.get():
 if event.type == QUIT:
 exit()
 if event.type == MOUSEBUTTONDOWN:
 if event.button==4:
 if select<9:
 select=select+1
 else:
 select=1
 elif event.button==5:
 if select>1:
 select=select-1
 else:
 select=9
 if select==1:
 blocksel=texdir+"\\dirt.png"
 btype='block'
 if select==2:
 blocksel=texdir+"\\stonetile.png"
 btype='block'
 if select==3:
 blocksel=texdir+"\\stone.png"
 btype='block'
 if select==4:
 blocksel=texdir+"\\sand.png"
 btype='block'
 if select==5:
 blocksel=texdir+"\\woodplank.png"
 btype='block'
 if select==6:
 blocksel=texdir+"\\woodslab.png"
 btype='slab'
 if key[K_LSHIFT]:
 if event.type==MOUSEMOTION:
 if not any(block.rect.collidepoint(mse) for block in blocklist):
 snd=random.randint(1,3)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 if go==1:
 if snd==1:
 place.play()
 elif snd==2:
 place2.play()
 elif snd==3:
 place3.play()
 blocklist.append(Block(x,y,blocksel,btype))
 if key[K_RSHIFT]:
 if event.type==MOUSEMOTION:
 to_remove = [b for b in blocklist if b.rect.collidepoint(mse)]
 for b in to_remove:
 if go==1:
 blocklist.remove(b)
 else:
 if event.type == pygame.MOUSEBUTTONUP:
 if event.button == 1:
 to_remove = [b for b in blocklist if b.rect.collidepoint(mse)]
 for b in to_remove:
 if go==1:
 blocklist.remove(b)
 if not to_remove:
 snd=random.randint(1,3)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 if go==1:
 if snd==1:
 place.play()
 elif snd==2:
 place2.play()
 elif snd==3:
 place3.play()
 blocklist.append(Block(x,y,blocksel,btype))
 elif event.button == 3:
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 player=Player(x+16,y+16)
 move = Move(key[K_w], key[K_a], key[K_d])
 for b in blocklist:
 if b.rect.left>=0:
 if b.rect.right<=640:
 screen.blit(b.sprite, b.rect)
 if player:
 player.update(move, blocklist)
 if anim==1 or anim==2 or anim==3:
 screen.blit(psprite, player.rect)
 elif anim==4 or anim==5 or anim==6:
 screen.blit(psprite2, player.rect)
 elif anim==7 or anim==8 or anim==9:
 screen.blit(psprite3, player.rect)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 screen.blit(curs,(x,y))
 clock.tick(60)
 x=blocksel.replace(texdir,'')
 x=x.replace('.png','')
 vers=font.render('PiBlocks Alpha 0.6',True,(255,255,255))
 tex=font.render('Selected Texture Pack: '+texdir,True,(255,255,255))
 words=font.render('Selected Block: '+str(x), True, (255,255,255))
 screen.blit(vers,(1,1))
 screen.blit(tex,(1,12))
 screen.blit(words,(1,25))
 if gotime==0:
 go=1
 else:
 gotime-=1
 pygame.display.update()
 elif ingame==0:
 blocklist=[]
 mse = pygame.mouse.get_pos()
 player=[]
 key = pygame.key.get_pressed()
 text=font.render(splash, True, (255,255,255))
 if key[K_RETURN]:
 ingame=1
 for event in pygame.event.get():
 if event.type == QUIT:
 exit()
 if event.type == KEYDOWN:
 print event.key
 if sbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 ingame='gen'
 top=(random.randint(5,8)*32)
 cen=(top+random.randint(4,6)*32)
 down=15
 across=0
 blklvl=0
 while across<640:
 while down>0:
 screen.fill((0,0,0))
 if blklvl==top:
 blocklist.append(Block(across,blklvl,texdir+"\\grass.png",'block'))
 if blklvl>top:
 if blklvl<cen:
 blocklist.append(Block(across,blklvl,texdir+"\\dirt.png",'block'))
 if blklvl>cen-1:
 blocklist.append(Block(across,blklvl,texdir+"\\stone.png",'block'))
 down=down-1
 blklvl=blklvl+32
 if down==0:
 if across<1920:
 per=(across/(32/5))
 if per>100:
 per=100
 top=(random.randint(5,8)*32)
 cen=(top+random.randint(4,6)*32)
 down=15 
 blklvl=0
 across=across+32
 down=15
 drawgen=font.render('GENERATION:'+str(per)+'%%', True, (255,255,255))
 screen.blit(drawgen,(1,1))
 pygame.display.flip()
 go=0
 ingame=1
 if qbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 exit()
 if tbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 ingame='texsel'
 screen.blit(backimg,(0,0))
 screen.blit(text,(364,76))
 screen.blit(sbtn,sbtnrect)
 screen.blit(qbtn,qbtnrect)
 screen.blit(tbtn,tbtnrect)
 pygame.display.flip()
 elif ingame=='texsel':
 screen.blit(clsimg,(0,0))
 inp = ask(screen, 'Texture Directory')
 f=open('texdir.txt','w')
 f.write(str(inp))
 f.close()
 pygame.display.flip()
 execfile('PiBlocks.pyw')

• Sam Tubb: Just changed the code to make it load each sprite one time, but it still runs quite slow!
• icktoofay: First thoughts: that's a lot of global variables, this should probably be split up into multiple files, and the indentation appears to be inconsistent.
• Sam Tubb: Do you mean multiple .py files?
• icktoofay: Yes. You may be able to split it up into multiple .py files and have them import each-other as modules.

Answer 1

First of all, a lot of people who would answer this question will not do so because you can't just copy/paste the code and run it. The code depends on a lot of external files, like images and textfiles, and to run your code, you basically have to trial'n'error your way while creating a bunch of placeholder images...

---

I'll try to read your code and comment it step by step.

f=open('texdir.txt','r')
texdir=f.read()
f.close()
f=open(texdir+"\\splash.txt",'r')
splash=f.read()
splash=splash.replace('(','')
splash=splash.replace(')','')
splash=splash.split(',')
f.close()
...
f=open(texdir+"//backcolor.txt") 

Here you read some settings/configurations. Better use the ConfigParser module. It will make your code more readable and more easily to follow.

---

splashlen=len(splash)
chc=random.randint(0,int(splashlen))
splash=splash[chc-1]

To select a random element from as list, you can just use random.choice.

---

f=open(texdir+"//backcolor.txt")
...
blocksel=texdir+"\\dirt.png"

Sometimes you use // in a path, sometimes \\. Better use os.path.join to create a path so it will work on different operating systems,

---

COLOR=f.read()
f.close()
COLOR=COLOR.replace('(','')
COLOR=COLOR.replace(')','')
COLOR=COLOR.split(',')
c1=COLOR[0]
c2=COLOR[1]
c3=COLOR[2]
...
if ingame==1:
 screen.fill((int(c1),int(c2),int(c3)))

Well, that's a whole lot of code to read a simple tuple. Let be point to ast.literal_eval, which allows you to savely read a string and convert it into a python structure:

line = f.read()
# assuming 'line' is a string representing a tuple, like (120, 120, 200)
back_color = literal_eval(line) # now, back_color is a tuple
...
if ingame==1:
 screen.fill(back_color)

---

if key[K_1]:
 blocksel=texdir+"\\dirt.png"
 btype='block'
 select=1
if key[K_2]:
 blocksel=texdir+"\\stonetile.png"
 btype='block'
 select=2

Here, you have three (maybe four if you count the key) values that are connectet to each other, so you should create a type that represents this:

class BlockType(object):
 def __init__(self, name, type, image_path=None, y_offset=0):
 self.name = name
 self.type = type
 if not image_path:
 image_path = name + '.png'
 self.image = pygame.image.load(image_path).convert()
 self.y_offset = y_offset
 def get_rect(self, x, y):
 return self.image.get_rect(top=y+self.y_offset, left=x)
class Block(object):
 def __init__(self, x, y, block_type):
 self.block_type = block_type
 self.image = block_type.image
 self.rect = block_type.get_rect(x, y)
 # don't know if we need the information 'block or slab' 
types = [BlockType('dirt', 'block'), 
 BlockType('stonetile', 'block'), 
 BlockType('stone', 'block'),
 BlockType('grass', 'block'),
 BlockType('sand', 'block'),
 BlockType('woodplank', 'block'),
 BlockType('woodslab', 'slab', y_offset=16)]
block_lookup = {t.name: t for t in types}
key_map = dict(zip([K_1, K_2, K_3, K_4, K_5, K_6], types))

Also, this will allow to remove a lot of code duplication.

---

if event.button==4:
 if select < 9:
 select=select+1
 else:
 select=1
elif event.button==5:
 if select>1:
 select=select-1
 else:
 select=9

can be simplified to

num_of_types = len(types)
if event.button==4:
 select += 1
elif event.button==5:
 select -= 1
select = max(min(select, num_of_types), 0)

---

if blklvl==top:
 blocklist.append(Block(across,blklvl,texdir+"\\grass.png",'block'))
if blklvl>top:
 if blklvl<cen:
 blocklist.append(Block(across,blklvl,texdir+"\\dirt.png",'block'))
if blklvl>cen-1:
 blocklist.append(Block(across,blklvl,texdir+"\\stone.png",'block'))

Notice how you repeat the filenames to each different block type all over again? Let's fix that by creating a factory method that uses our new block_lookup dictionary:

# this lookup could also be directly in the Block class
def block_factory(name, x, y):
 return Block(x, y, block_lookup[name])
...
if blklvl == top:
 blocklist.append(block_factory(across, blklvl , 'grass'))
if blklvl > top and blklvl<cen:
 blocklist.append(block_factory(across, blklvl , 'dirt'))
if blklvl > cen-1:
 blocklist.append(block_factory(across, blklvl , 'stone'))

---

vers=font.render('PiBlocks Alpha 0.6',True,(255,255,255))
tex=font.render('Selected Texture Pack: '+texdir,True,(255,255,255))

You render the text surface once each frame. Text rendering in pygame is quite slow, so you should cache the text surfaces and reuse them.

---

for block in blocklist:
 if any(block.rect.colliderect(b.rect) for b in blocklist if b is not block):
 if b.btype=='slab':
 blocklist.remove(block)
 else:
 blocklist.remove(b)

No idea what you try to do here. b is declared in the list comprehension above and should not be used outside of it.

---

There's a lot more what could be improved, but we've already eliminated two performance bottlenecks (reloading images from disk every time a new block is created, text rendering), and I'm running out of space and time, so here's the complete code so far:

#Init stuff
import pygame,random
from pygame.locals import *
from collections import namedtuple
import time, string
import ConfigParser
from ast import literal_eval
from functools import partial
import os
config = ConfigParser.ConfigParser()
config.read("settings.cfg")
options = partial(config.get, 'Options')
pygame.mixer.init(frequency=22050, size=-16, channels=2, buffer=500)
pygame.init()
pygame.display.set_caption(options('Caption'))
size = literal_eval(options('ScreenSize'))
screen = pygame.display.set_mode(size)
clock = pygame.time.Clock()
back_color = literal_eval(options('Backcolor'))
splash = random.choice(literal_eval(options('Splash')))
max_gravity = 100
texdir = options('TextureDir')
backimg = pygame.image.load(texdir+"\\menu.png").convert()
backimg = pygame.transform.scale(backimg, (640,480))
clsimg = pygame.image.load("clear.bmp").convert()
clsimg = pygame.transform.scale(clsimg, (640,480))
ingame=0
sbtn=pygame.image.load("startbtn.png").convert()
qbtn=pygame.image.load("quitbtn.png").convert()
tbtn=pygame.image.load("texbtn.png").convert()
sbtnrect=sbtn.get_rect()
sbtnrect.x=220
sbtnrect.y=190
qbtnrect=qbtn.get_rect()
qbtnrect.x=220
qbtnrect.y=225
tbtnrect=tbtn.get_rect()
tbtnrect.x=220
tbtnrect.y=260
go=0
gotime=35
select=1
colliding = False
Move = namedtuple('Move', ['up', 'left', 'right'])
player=[]
blocklist=[]
font=pygame.font.Font(None,18)
#set cursor
curs = pygame.image.load(texdir+"\\cursor.png").convert()
curs.set_colorkey((0,255,0))
#load sounds
place=pygame.mixer.Sound('sound\\place.wav')
place2=pygame.mixer.Sound('sound\\place2.wav')
place3=pygame.mixer.Sound('sound\\place3.wav')
#set sprites and animation frames
psprite = pygame.image.load(texdir+"\\player\\playr.png").convert()
psprite.set_colorkey((0,255,0))
psprite2 = pygame.image.load(texdir+"\\player\\playr2.png").convert()
psprite2.set_colorkey((0,255,0))
psprite3 = pygame.image.load(texdir+"\\player\\playr3.png").convert()
psprite3.set_colorkey((0,255,0))
anim=1
class BlockType(object):
 def __init__(self, name, type, image_path=None, y_offset=0):
 self.name = name
 self.type = type
 if not image_path:
 image_path = name + '.png'
 self.image = pygame.image.load(image_path).convert()
 self.y_offset = y_offset
 def get_rect(self, x, y):
 return self.image.get_rect(top=y+self.y_offset, left=x)
class Block(object):
 def __init__(self, x, y, block_type):
 self.block_type = block_type
 self.image = block_type.image
 self.rect = block_type.get_rect(x, y)
types = [BlockType('dirt', 'block'), 
 BlockType('stonetile', 'block'), 
 BlockType('stone', 'block'),
 BlockType('grass', 'block'),
 BlockType('sand', 'block'),
 BlockType('woodplank', 'block'),
 BlockType('woodslab', 'slab', y_offset=16)]
block_lookup = {t.name: t for t in types}
def block_factory(name, x, y):
 return Block(x, y, block_lookup[name])
num_of_types = len(types)
key_map = dict(zip([K_1, K_2, K_3, K_4, K_5, K_6], types))
selected_block_type = next(t for t in types if t.name == options('DefaultBlock'))
selected_block_index = types.index(selected_block_type) 
_text_cache = {}
def render_white(text):
 if not text in _text_cache:
 surf = font.render(text ,True,(255,255,255))
 _text_cache[text] = surf
 return surf
 return _text_cache[text]
class Player(object):
 sprite=psprite
 def __init__(self, x, y):
 self.rect = self.sprite.get_rect(centery=y, centerx=x)
 # indicates that we are standing on the ground
 # and thus are "allowed" to jump
 self.on_ground = True
 self.xvel = 0
 self.yvel = 0
 self.jump_speed = 7
 self.move_speed = 3
 def update(self, move, blocks):
 # check if we can jump 
 if move.up and self.on_ground:
 self.yvel -= self.jump_speed
 # simple left/right movement
 if move.left:
 self.xvel = -self.move_speed
 if move.right:
 self.xvel = self.move_speed
 # if in the air, fall down
 if not self.on_ground:
 self.yvel += 0.3
 # but not too fast
 if self.yvel > max_gravity: self.yvel = max_gravity
 # if no left/right movement, x speed is 0, of course
 if not (move.left or move.right):
 self.xvel = 0
 # move horizontal, and check for horizontal collisions
 self.rect.left += self.xvel
 self.collide(self.xvel, 0, blocks)
 # move vertically, and check for vertical collisions
 self.rect.top += self.yvel
 self.on_ground = False;
 self.collide(0, self.yvel, blocks)
 def collide(self, xvel, yvel, blocks):
 # all blocks that we collide with
 for block in [blocks[i] for i in self.rect.collidelistall(blocks)]:
 # if xvel is > 0, we know our right side bumped 
 # into the left side of a block etc.
 if xvel > 0:
 self.rect.right = block.rect.left
 if xvel < 0:
 self.rect.left = block.rect.right
 # if yvel > 0, we are falling, so if a collision happpens 
 # we know we hit the ground (remember, we seperated checking for
 # horizontal and vertical collision, so if yvel != 0, xvel is 0)
 if yvel > 0:
 self.rect.bottom = block.rect.top
 self.on_ground = True
 self.yvel = 0
 # if yvel < 0 and a collision occurs, we bumped our head
 # on a block above us
 if yvel < 0: self.rect.top = block.rect.bottom
def get_key():
 while 1:
 event = pygame.event.poll()
 if event.type == KEYDOWN:
 return event.key
 else:
 pass
def display_box(screen, message):
 "Print a message in a box in the middle of the screen"
 fontobject = pygame.font.Font(None,18)
 pygame.draw.rect(screen, (0,0,0),
 ((screen.get_width() / 2) - 100,
 (screen.get_height() / 2) - 10,
 200,20), 0)
 pygame.draw.rect(screen, (255,255,255),
 ((screen.get_width() / 2) - 102,
 (screen.get_height() / 2) - 12,
 204,24), 1)
 if len(message) != 0:
 screen.blit(fontobject.render(message, 1, (255,255,255)),
 ((screen.get_width() / 2) - 100, (screen.get_height() / 2) - 10))
 pygame.display.flip()
def ask(screen, question):
 "ask(screen, question) -> answer"
 pygame.font.init()
 current_string = []
 display_box(screen, question + ": " + string.join(current_string,""))
 while 1:
 inkey = get_key()
 if inkey == K_BACKSPACE:
 current_string = current_string[0:-1]
 elif inkey == K_RETURN:
 break
 elif inkey == K_MINUS:
 current_string.append("_")
 elif inkey <= 127:
 current_string.append(chr(inkey))
 display_box(screen, question + ": " + string.join(current_string,""))
 return string.join(current_string,"")
while True:
 for block in blocklist:
 if any(block.rect.colliderect(b.rect) for b in blocklist if b is not block):
 blocklist.remove(block)
 if ingame==1:
 screen.fill(back_color)
 mse = pygame.mouse.get_pos()
 key = pygame.key.get_pressed()
 if key[K_a]:
 anim+=1
 if anim==9:
 anim=1
 if key[K_d]:
 anim+=1
 if anim==9:
 anim=1
 if key[K_LEFT]:
 try:
 for b in blocklist:
 b.rect.left+=32
 except:
 pass
 try:
 player.rect.left+=32
 except:
 pass
 if key[K_RIGHT]:
 try:
 for b in blocklist:
 b.rect.left-=32
 except:
 pass
 try:
 player.rect.left-=32
 except:
 pass
 if key[K_UP]:
 try:
 for b in blocklist:
 b.rect.top+=32
 except:
 pass
 try:
 player.rect.top+=32
 except:
 pass
 if key[K_DOWN]:
 try:
 for b in blocklist:
 b.rect.top-=32
 except:
 pass
 try:
 player.rect.top-=32
 except:
 pass
 if key[K_ESCAPE]:
 execfile('PiBlocks.pyw')
 for event in pygame.event.get():
 if event.type == QUIT:
 exit()
 if event.type == MOUSEBUTTONDOWN:
 if event.button == 4:
 selected_block_index += 1
 elif event.button == 5:
 selected_block_index -= 1
 selected_block_index = max(min(selected_block_index, num_of_types-1), 0)
 selected_block_type = types[selected_block_index]
 elif event.type == KEYDOWN:
 if event.key in key_map:
 selected_block_type = key_map[event.key]
 selected_block_index = types.index(selected_block_type)
 elif event.type==MOUSEMOTION:
 if key[K_LSHIFT]:
 if not any(block.rect.collidepoint(mse) for block in blocklist):
 snd=random.randint(1,3)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 if go==1:
 if snd==1:
 place.play()
 elif snd==2:
 place2.play()
 elif snd==3:
 place3.play()
 blocklist.append(Block(x,y,selected_block_type))
 elif key[K_RSHIFT]:
 to_remove = [b for b in blocklist if b.rect.collidepoint(mse)]
 for b in to_remove:
 if go==1:
 blocklist.remove(b)
 elif event.type == pygame.MOUSEBUTTONUP:
 if event.button == 1:
 to_remove = [b for b in blocklist if b.rect.collidepoint(mse)]
 for b in to_remove:
 if go==1:
 blocklist.remove(b)
 if not to_remove:
 snd=random.randint(1,3)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 if go==1:
 if snd==1:
 place.play()
 elif snd==2:
 place2.play()
 elif snd==3:
 place3.play()
 blocklist.append(Block(x,y,selected_block_type))
 elif event.button == 3:
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 player=Player(x+16,y+16)
 move = Move(key[K_w], key[K_a], key[K_d])
 for b in blocklist:
 if b.rect.left>=0:
 if b.rect.right<=640:
 screen.blit(b.image, b.rect)
 if player:
 player.update(move, blocklist)
 if anim==1 or anim==2 or anim==3:
 screen.blit(psprite, player.rect)
 elif anim==4 or anim==5 or anim==6:
 screen.blit(psprite2, player.rect)
 elif anim==7 or anim==8 or anim==9:
 screen.blit(psprite3, player.rect)
 x=(int(mse[0]) / 32)*32
 y=(int(mse[1]) / 32)*32
 screen.blit(curs,(x,y))
 clock.tick(60)
 screen.blit(render_white('PiBlocks Alpha 0.6'), (1,1))
 screen.blit(render_white('Selected Texture Pack: ' + texdir), (1,12))
 screen.blit(render_white('Selected Block: '+ selected_block_type.name), (1,25))
 if gotime==0:
 go=1
 else:
 gotime-=1
 pygame.display.update()
 elif ingame==0:
 blocklist=[]
 mse = pygame.mouse.get_pos()
 player=[]
 key = pygame.key.get_pressed()
 text=font.render(splash, True, (255,255,255))
 if key[K_RETURN]:
 ingame=1
 for event in pygame.event.get():
 if event.type == QUIT:
 exit()
 if event.type == KEYDOWN:
 print event.key
 if sbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 ingame='gen'
 top=(random.randint(5,8)*32)
 cen=(top+random.randint(4,6)*32)
 down=15
 across=0
 blklvl=0
 while across<640:
 while down>0:
 screen.fill((0,0,0))
 if blklvl==top:
 blocklist.append(block_factory('grass', across, blklvl))
 if blklvl>top and blklvl<cen:
 blocklist.append(block_factory('dirt', across, blklvl))
 if blklvl>cen-1:
 blocklist.append(block_factory('stone', across, blklvl))
 down=down-1
 blklvl=blklvl+32
 if down==0:
 if across<1920:
 per=(across/(32/5))
 if per>100:
 per=100
 top=(random.randint(5,8)*32)
 cen=(top+random.randint(4,6)*32)
 down=15 
 blklvl=0
 across=across+32
 down=15
 drawgen=font.render('GENERATION:'+str(per)+'%%', True, (255,255,255))
 screen.blit(drawgen,(1,1))
 pygame.display.flip()
 go=0
 ingame=1
 if qbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 exit()
 if tbtnrect.collidepoint(mse):
 if pygame.mouse.get_pressed()==(1,0,0):
 ingame='texsel'
 screen.blit(backimg,(0,0))
 screen.blit(text,(364,76))
 screen.blit(sbtn,sbtnrect)
 screen.blit(qbtn,qbtnrect)
 screen.blit(tbtn,tbtnrect)
 pygame.display.flip()
 elif ingame=='texsel':
 screen.blit(clsimg,(0,0))
 inp = ask(screen, 'Texture Directory')
 f=open('texdir.txt','w')
 f.write(str(inp))
 f.close()
 pygame.display.flip()
 execfile('PiBlocks.pyw')

and the config file (settings.cfg):

[Options]
Backcolor: (100, 100, 100)
TextureDir: .
DefaultBlock: dirt
ScreenSize: (640, 480)
Caption: PiBlocks | By Sam Tubb
Splash: ('Some splash!', 'Play This!', 'Whhooooaaaa!!')

Further steps are fixing indentation, clean up the deep nesting of if blocks, maybe introduce classes that represent the different game states, and removing the evil empty try/except blocks. Also, some code of blocks could also extrated to functions to improve readability.