Been struggling with this for a couple of days, hard to find code examples on the net.
I'm making a topdown game and having trouble getting the player to move on key press. At the moment i'm using add_force or add_impulse to move the player in a direction, but the player doesn't stop.
I've read about using surface friction between the space and the player to simulate friction and here is how it's done in the tank.c demo.
However I don't understand the API enough to port this code from chipmunk into pymunk.
cpConstraint *pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(tankControlBody, tankBody, cpvzero, cpvzero));
So far, I have something that looks like this:
class Player(PhysicalObject):
BASE_SPEED = 5
VISIBLE_RANGE = 400
def __init__(self, image, position, world, movementType=None):
PhysicalObject.__init__(self, image, position, world)
self.mass = 100
self.CreateBody()
self.controlBody = pymunk.Body(pymunk.inf, pymunk.inf)
self.joint = pymunk.PivotJoint(self.body, self.controlBody, (0,0))
self.joint.max_force = 100
self.joint.bias_coef = 0
world.space.add(self.joint)
I don't know how to add the constraint of the space/player to the space.
(Need someone with 1500+ rep to create a pymunk tag for this question).
Joe crossposted the question to the Chipmunk/pymunk forum, and it got a couple of more answers there. http://www.slembcke.net/forums/viewtopic.php?f=1&t=1450&start=0&st=0&sk=t&sd=a
Ive pasted/edited in parts of my answer from the forum below:
#As pymunk is python and not C, the constructor to PivotJoint is defined as
def __init__(self, a, b, *args):
pass
#and the straight conversion from c to python is
pivot1 = PivotJoint(tankControlBody, tankBody, Vec2d.zero(), Vec2d.zero())
# but ofc it works equally well with 0 tuples instead of the zero() methods:
pivot2 = PivotJoint(tankControlBody, tankBody, (0,0), (0,0))
mySpace.add(pivot1, pivot2)
Depending on if you send in one or two arguments to args, it will either use the cpPivotJointNew or cpPivotJointNew2 method in the C interface to create the joint. The difference between these two methods is that cpPivotJointNew want one pivot point as argument, and the cpPivotJointNew2 want two anchor points. So, if you send in one Vec2d pymunk will use cpPivotJointNew, but if you send in two Vec2d it will use cpPivotJointNew2.
Full PivotJoint constructor documentation is here: PivotJoint constructor docs
I'm not familiar with either system you've mentioned, but some basic game ideas that may relate are:
If you add a force (or impulse) which affects movement, for the entity to stop, you must also take it away. In my games if I had a function AddImpulse()/AddForce() I would have a corresponding one such as Apply_Friction() which would reverse the effect by however much you want (based on terrain?) until movespeed is zero or less. I personally wouldn't bother with this method for movement unless needed for gameplay since it can add more computations that its worth each update.
There should be some way to track KeyPressed and/or KeyPosition and then using those x/y coordinates are incrememnted based on player speed. Without knowing what you've tried or how much the API does for you, it's hard to really say more.
Hope this helps. If this is stuff you already knew kindly ignore it.
Related
I want Python to kind of ignore a statement that is unlikely to be called in a function that is often called.
I do not have a formal education in programming, so please excuse my lackluster ability to desribe things. I will try to explain the concept by example.
Say I am writing a video game, first-person shooter, drawing 60 frames per second.
In the settings menu, the user can select whether or not to display the name of other players above their head. If they disable this, I store this value as showplayernames = False.
Then in my drawing function that outputs the graphics I have:
def draw():
#code that draws the graphics on screen
if showplayernames:
#code that draws the name of players on screen
I call this function 60 times a second, but there is absolutely no point for checking if showplayernames is True 60 times a second. It will not change that often, in fact I could make this a kind of "constant" during play by preventing it to change. If showplayernames is False, then the third and fourth lines of the code are completely redundant, but they are executed nevertheless. The computer isn't smart enough to know it can ignore it, and there is a performance difference: reading a value and then checking if it is false takes time.
I could write two copies of the game (or at least the draw() function), one with only the first two lines when the user selects not to show names in the settings, and another without the if statement, and then run the appropriate one.
def draw_with_names():
#code that draws the graphics on screen
#code that draws the name of players on screen
def draw_without_names():
#code that draws the graphics on screen
Although looping through either of these 60 times a second is more efficient than running draw() ,this is obviously not the way to go. There are dozens of settings like this.
So how do software and game designers implement these kind of "software-wide" settings efficiently?
I'm not a game developer, but here's one option. Create a list of function pointers and add or remove from the list based on settings. Example:
def draw_player_names():
# Code to overlay names
def draw_fps():
# Code to overlay fps
def draw():
# Main code to draw a frame of the game
# Hold all the functions to call
optional_funcs = []
if showplayernames: optional_funcs.append(draw_player_names)
if show_fps: optional_funcs.append(draw_fps)
# Main game loop
while True:
draw()
for f in optional_funcs: f()
This can be extended for any number of functions/options.
not an game designer, but here is my voice.
You could store settings inside json file next to you python, but then you need to cover reading, getting right values etc.
You could use Environment variables to store value but that would end up using still "if" in the code.
Game designers use triggers and events to get things done, and on the lowest level I would assume those things also use if's.
system-wide-settings will in the end be used with if's
You could use overwrites based on event/trigger and use "same" draw function in both times but that only complicates code, and we all know to "keep it simple".
Sorry if this is not the answer you were looking for.
As Matthias said, you shouldn't really bother about this kind of optimization. Look at these two very silly functions:
def lot_of_ifs(settings):
#do something
a=2**10
b=2**10
c=2**10
for setting in settings:
if setting:
#do something more
a=2**10
b=2**10
c=2**10
def no_ifs():
#do something
a=2**10
b=2**10
c=2**10
timeit("lot_of_ifs([0,0,0,0,0])", globals=globals())
0.2630380000000514
timeit("no_ifs()", globals=globals())
0.10232830000040849
The cost of creating a list, looping over it, and executing five ifs is about 0.16 seconds for one million iterations, or 160 nanoseconds per iteration, while at 60 fps you have 16.6 million nanoseconds to execute your code.
I'm making my own game with Python2.7 through the pygame libraby.
It's a 1v1 combat game where players use the same keyboard.
The game works in a main loop that is repeated 60times per second, every time the loop is executed, it calculates lots of things e.g the position, problem is that I have 2 players, so I have to write the lines two times.
Example here:
if p1direction == 'right' and p1XS < p1Attributes[1]: p1XS +=
p1Attributes[0]
and:
if p2direction == 'right' and p2XS < p2Attributes[1]: p2XS +=
p2Attributes[0]
See the differences p1 and p2, they are variables that belongs to Player 1 and Player 2 respectively.
I just want to find a solution to not write every time the same lines just for p2. I was thinking about the for function so I can even add players easly but I don't know how to do it in this case...
Can someone help me ? :) Please
Create a class player.
Then add the attributes of each player to the class.
Instantiate your class with player 1 and 2.
class Player():
direction = "right"
etc.
def shoot(self):
if self.direction == "right"
shoot_right()
playerOne = Player()
playerTwo = Player()
direction = playerOne.direction
If you haven't used classes yet, I wouldn't recommend using them though. Inheritance can get pretty nasty...
Hope that helped,
Narusan
EDIT:
If you haven't used classes in Python yet, I recommend catching up there first and then continuing your game development. I have programmed several games in pygame as well, and classes come in very hand. In fact, it is almost impossible to create pygame games without using proper classes (or endless if-clauses and for-loops that will make everything super slow).
Wish you all the best of luck
How about storing your variables(for example p1direction and p2direction) in a vector(player_directions) indexed by the player number and using a loop access it, for example:
number_of_players = 2
playersXS = function_that_fills_playersXS() # return a vector containing your p1XS and p2XS variables in a vector
for player_number in xrange(number_of_players):
if player_directions[player_number]=='right' and playersXS[player_number]< Attributes[player_number][1]:
playersXS[player_number]+=Attributes[player_number][0]
I don't know what the right words are to ask my question, so please excuse the extra detail below. I am as much asking for the right words/concepts as for an answer to the specific question.
I'm trying to put a simple console in front of a script of mine using curses in Python. I want the console to look relatively familiar and have key shortcuts for 3 commands (Load, Exit, Continue). To highlight which key is the hotkey for an action, I wanted that letter to be in a different colour. (e.g. Exit with hotkey being the x). I figure this must be made up of 3 "addstr" commands- write the first letter in normal ("E"), then the x with a colour attribute, then "it" in normal colour again.
I thought that because I do this 3 times, and maybe more in future screens, I should make a function to do it for me to see if that works. What I can't figure out though, is how to edit the screen without hardcoding the function to the variable name. I want to be able to call the function in a number of different windows. I thought at first I could just pass the screen's variable into my function but that doesn't seem right.
Here is my pseudo code I started working on:
def keyString(menuString,fastChar,highlight,startX,startY,cScreen):
#menuString is the word that has a letter to bring to attention
#fastChar is the character that will be in a different colour
#highlight is binary value to determine which colour pair to use
#definition expects 'h' and 'n' to be colour pairs
#startX and startY are the beginning cursor positions
#cScreen would be global screen variable
fCidx = menuString.find(fastChar) #index of the character to highlight
fXadj = startX + fCidx #set the x position for character to highlight
sHx = fXadj + 1 #set the x position for the remainder of the string
fH = menuString[0:fCidx] #Slice the first half of the string
sH = menuString[(fCidx+1):] #slice the remainder of the string
if highlight:
txtColor = h
else:
txtColor = n
cScreen.addstr(startY,startX,fH,txtColor)
cScreen.addstr(startY,fXadj,fastChar)
cScreen.addstr(startY,sHx,sH,txtColor)
return cScreen
Please ignore the awful variable names..I was getting tired of typing and started shorthanding. I realise that I didn't need to worry about explicitly stating x,y coords because the cursor position is remembered. So a lot of that can be cut out. I'm not asking for someone to fix my function. I just don't have a concept of how to have a function that will write out a word using different colours for different characters. I could probably stick a "global screen" in the function and only use it for editing "screen", but then (for example) I wouldn't be able to use the function for "screen2".
If it helps anyone searching in the future, I found that I can use Windows (curses.newwin) and those can be fed into, and returned from functions.
So for example, if the above code was in a file called "curse_tools.py":
import curses
import curse_tools
def Main(screen):
curses.init_pair(1,curses.COLOR_GREEN, curses.COLOR_BLACK)
curses.init_pair(2,curses.COLOR_BLACK, curses.COLOR_GREEN)
n = curses.color_pair(1)
h = curses.color_pair(2)
curse_tools.n = n
curse_tools.h = h
try:
screen.border(0)
box1 = curses.newwin(20, 20, 5, 5)
box1.box()
box1=curse_tools.keyString("Exit","x",False,1,1,box1)
screen.refresh()
box1.refresh()
screen.getch()
finally:
curses.endwin()
curses.wrapper(Main)
This code would work. I'm going to re-write my original code because I learned a lot along the way but maybe a future beginner will somehow come across this question so I thought I'd post the 'solution'. Although I still don't know the right words.
Most of the code in this post came from Why won't my curses box draw? (in case it looks familiar)
I'm in the process of creating a 2d platformer using the Blender Game Engine. I'm having trouble getting the camera to follow my character and keep him in the center of the screen. Initially, I tried simply parenting the camera to my character, but whenever my character turns (rotates around the Z-axis 180 degrees), so does my camera, making it face the back of the level. So, I was wondering if there was a way to "parent" only one or two axes of an object to another, or restrain an axes from moving even if it is parented. This way I could keep the camera from rotating, but still have it follow on the Y and Z axes.
One thing I looked into was using Python code. I came up with...
import bpy
char = bpy.data.objects['HitBox']
obj = bpy.data.objects['Camera']
obj.location.x = 69.38762 # this is the set distance from the character to camera
obj.location.y = char.location.y
obj.location.z = char.location.z
bpy.data.scenes[0].update()
I realize I need a loop for this after assigning the 'char' variable, but I can't get any Python loops working that would run through the entire game, as 'while' loops crash the BGE. If you could help with either the parenting issue, or the Python code, I'd really appreciate it.
you just need to use the bge module, because it is for the game engine. So your problem is: you used blender python, but not bge python. Try to reach the camera with cam = bge.logic.getCurrentScene().active_camera. ... so this should work:
import bge
def main():
cam = bge.logic.getCurrentScene().active_camera
obj = bge.logic.getCurrentController().owner
obj.worldPosition.y = cam.worldPosition.y
obj.worldPosition.z = cam.worldPosition.z
main()
(Attach this script to your 'HitBox' with a true triggered always sensor so it can cycle forever.)
Other solution:
You can try to make vertex parent to your player.
I am using python and pyglet in a 2d game but I have come across a problem in collision detection. My code to check for collision looks like this:
def distance(self,target):
return math.sqrt((self.x-target.x)**2 + (self.y-target.y)**2)
def check_collision(self):
for i in list_of_mobs:
if self.distance(i) < (self.width/2 + i.width/2):
return True
It checks the distance from each sprite with "target" being another sprite. The thing I am unsure of is "should I be checking for collisions between all the sprites?" I have over 200 mobs (even more I hope in the finished product) and it becomes unplayable when the collisions are checked. Is there someway to only check sprites within a certain distance without losing speed?
EDIT:
I had a read around google and found out that a lot of the speed was spent doing the same collisions. i.e. sprite1 was checked with sprite2 and sprite2 was checked with sprite1. So I made a few changes to the check collision function and it runs quicker now but still less than 20 fps
def check_collision(self):
global mobs_to_collide
if mobs_to_collide == []:
mobs_to_collide = list_of_mobs[:]
if self in mobs_to_collide:
mobs_to_collide.remove(self)
for i in mobs_to_collide:
if self.distance(i) < (self.width/2 + i.width/2):
return True
(it may contain some inefficient code/useless stuff. I was playing around with it a bit)
EDIT2:
I decided to use rabbyt as the sprite library. The collisions are fast and easy. I replaced the code above ^^ with:
rabbyt.collisions.collide(mobs_to_collide)
This returns a list of lists (I'm not sure if that's the correct term) with the objects that collided. I'm still working on how to translate that into an "if collided:" type statement but I am making progress. If anyone is in a similar situation, I would reccomend using rabbyt.
A simple way to improve the speed on this, could be to remove the square root operation.
def distancesq(self,target):
return (self.x-target.x)**2 + (self.y-target.y)**2
def check_collision(self):
for i in list_of_mobs:
# Square this distance to compensate
if self.distancesq(i) < (self.width/2 + i.width/2)**2:
return True
Probably it is already too late, but I had exactly the same problem. I managed to solve it by calculating collisions only for visible objects, like that:
for object_ in objects:
if not object_.visible: # pyglet.sprite.Sprite() provides this flag
continue
# rest of your collision detection