I have a basic implementation of Conway's game of life written in elm running at uminokirin.com.
The source is visible here.
The program let users adjust the size of the toroïdal grid, click on cells to change their status, and randomize the world. It works well for small values (less than 50) on my computer.
However when attempting to use the randomize grid function on bigger grids (the threshold value doesn't seem to be always the same), the program becomes unresponsive without any warning and the only way to recover is to reload the app.
There is zero optimization in the GOL algorithm and using a single svg rectangle for every cell is probably horribly inefficient, but it sill doesn't explain why the program behaves in this way instead of say, slowing down.
Is this the elm runtime giving up? Or some kind of browser safeguard?
More importantly is there a way to prevent this behavior other than arbitrarily capping the maximum size of the grid?
The behavior you are observing is due to a Javascript stack overflow. After pressing the "randomize" button, in the browser console you can see the message "Uncaught RangeError: Maximum call stack size exceeded"
This happens because the randomize function allocates several large temporary variables. In particular, the shuffle function (which is called from the randomize function) appears to allocate two temporary lists that each have one element for every cell in the life grid. Elm may be smart about releasing these on a timely basis but this appears to push it too far.
To fix this you can use a simpler randomize function. The version shown below uses Elm Generators to generate a single list of Dead/Alive values and then initializes the randomized array from that list.
randomize2 : Array Cell -> Int -> Int -> Int -> Array Cell
randomize2 grid gs sd n =
let floatGen = Random.float 0.0 1.0
lifeGen = Random.map (\b -> if (b < toFloat n/100) then Alive else Dead) floatGen
listGen = Random.list (gs*gs) lifeGen
in fst (Random.step listGen (initialSeed sd)) |> fromList
Using this randomize function I was able to resize the grid up to 600x600 and randomize successfully. At that point I stopped testing.
Related
So basically im doing this for my minecraft spigot plugin (java). I know there are already some land claim plugins but i would like to make my own.
For this claim plugin i'd like to know how to get if a point (minecraft block) is inside a region (rectangle). i know how to check if a point is inside a rectangle, the main problem is how to check as quickly as possible when there are like lets say 10.000 rectangles.
What would be the most efficient way to check 10.000 or even 100.000 without having to manually loop through all of them and check every single rectangle?
Is there a way to add a logical test when the rectangles get generated in a way that checks if they hold that point? In that case you could set a boolean to true if they contain that point when generated, and then when checking for that minecraft block the region (rectangle) replies with true or false.
This way you run the loops or checks when generating the rectangles, but when running the game the replies should happen very fast, just check if true or false for bool ContainsPoint.
If your rectangles are uniformly placed neighbors of each other in a big rectangle, then finding which rectangle contains point is easy:
width = (maxX-minX)/num_rectangles_x;
height = same but for y
idx = floor( (x - minX)/width );
idy = floor( (y - minY)/height );
id_square = idx + idy*num_rectangles_x;
If your rectangles are randomly placed, then you should use a spatial acceleration structure like octree. Then check if point is in root, then check if point is in one of its nodes, repeat until you find a leaf that includes the point. 10000 tests per 10milliseconds should be reachable on cpu. 1 million tests per 10ms should be ok for a gpu. But you may need to implement a sparse version of the octree and a space filling curve order for leaf nodes to have better caching, to reach those performance levels.
So I have my Q and E set to control a Camera that is fixed in 8 directions. The problem is when I call Input.is_action_just_pressed() it sets true two times, so it does its content twice.
This is what it does with the counter:
0 0 0 0 1 1 2 2 2 2
How can I fix thix?
if Input.is_action_just_pressed("camera_right", true):
if cardinal_count < cardinal_index.size() - 1:
cardinal_count += 1
else:
cardinal_count = 0
emit_signal("cardinal_count_changed", cardinal_count)
On _process or _physics_process
Your code should work correctly - without reporting twice - if it is running in _process or _physics_process.
This is because is_action_just_pressed will return if the action was pressed in the current frame. By default that means graphics frame, but the method actually detect if it is being called in the physics frame or graphic frame, as you can see in its source code. And by design you only get one call of _process per graphics frame, and one call of _physics_process per physics frame.
On _input
However, if you are running the code in _input, remember you will get a call of _input for every input event. And there can be multiple in a single frame. Thus, there can be multiple calls of _input where is_action_just_pressed. That is because they are in the same frame (graphics frame, which is the default).
Now, let us look at the proposed solution (from comments):
if event is InputEventKey:
if Input.is_action_just_pressed("camera_right", true) and not event.is_echo():
# whatever
pass
It is testing if the "camera_right" action was pressed in the current graphics frame. But it could be a different input event that one being currently processed (event).
Thus, you can fool this code. Press the key configured to "camera_right" and something else at the same time (or fast enough to be in the same frame), and the execution will enter there twice. Which is what we are trying to avoid.
To avoid it correctly, you need to check that the current event is the action you are interested in. Which you can do with event.is_action("camera_right"). Now, you have a choice. You can do this:
if event.is_action("camera_right") and event.is_pressed() and not event.is_echo():
# whatever
pass
Which is what I would suggest. It checks that it is the correct action, that it is a press (not a release) event, and it is not an echo (which are form keyboard repetition).
Or you could do this:
if event.is_action("camera_right") and Input.is_action_just_pressed("camera_right", true) and not event.is_echo():
# whatever
pass
Which I'm not suggesting because: first, it is longer; and second, is_action_just_pressed is really not meant to be used in _input. Since is_action_just_pressed is tied to the concept of a frame. The design of is_action_just_pressed is intended to work with _process or _physics_process, NOT _input.
So, apparently theres a built in method for echo detection:
is_echo()
Im closing this.
I've encountered the same issue and in my case it was down to the fact that my scene (the one containing the Input.is_action_just_pressed check) was placed in the scene tree, and was also autoloaded, which meant that the input was picked up from both locations and executed twice.
I took it out as an autoload and Input.is_action_just_pressed is now triggered once per input.
I've followed "Procedural Generation in Godot: Dungeon Generation" by KidsCanCode #https://www.youtube.com/watch?v=o3fwlk1NI-w and find myself unable to debug the current problem.
This specific commit has the code, but I'll try to explain in more detail bellow.
My main scene has a Camera2D node, a generic Node2D calles Rooms and a TileMap, everything is empty.
When the script starts, it runs a
func make_room(_pos, _size):
position = _pos
size = _size
var s = RectangleShape2D.new()
s.custom_solver_bias = 0.5
s.extents = size
$CollisionShape2D.shape = s
A few times and it fills $Rooms using .add_child(r) where r is a instance of the node that has the make_room() function. It will then iterate over $Rooms.get_children() a few times to create a AStar node to link all the rooms:
The magic comes when make_map() is called after afterwards, it fills the map with non-walkable blocks and then it carves the empty spaces, which works fine too:
There is a find_start_room() that is called to find the initial room, it also sets a global variable to the Main script start_room, which is used to write 'Start' on the map using draw_string(font, start_room.position - Vector2(125,0),"start",Color(3,4,8))
When I hit 'esc' it runs this simple code to instance the player:
player = Player.instance()
add_child(player)
player.position = start_room.position + Vector2(start_room.size.x/2, start_room.size.y/2)
play_mode = true
The problem comes when spawning the player. I tried doing some 'blind' fixing, such as adding or subtracting a Vector2(start_room.size.x/2, start_room.size.y/2) to player.position to see if I could make it fall within the room, to no avail.
Turning to the debugger didn't help, as the positions expressed by the variable inspectors don't seem to mean anything.
I tried implementing a simple 'mouse click print location':
print("Mouse Click/Unclick at: ", event.position)
print("Node thing",get_node("/root/Main/TileMap").world_to_map(event.position))
And also a 'start_room' print location:
print(get_node("/root/Main/TileMap").world_to_map(start_room.position))
And a when player moves print location, written directly into the Character script:
print(get_node("/root/Main/TileMap").world_to_map(self.position))
Getting results like the ones bellow:
Mouse Click/Unclick at: (518, 293)
Node thing(16, 9)
(-142, 0)
(-147, -3)
So, the player doesn't spawn on the same position as the start_room and the mouse position information is not the same as anything else.
Why is the player now spawning correctly? How can I debug this situation?
EDIT1: User Theraot mentioned about how the RigidBody2D is doing some weird collisions, and from what I understood, changing their collision behavior should fix the whole thing.
There's a section on the code that -after generating the random rooms- it removes some of the rooms like this:
for room in $Rooms.get_children():
if randf() < cull:
room.queue_free()
else:
room.mode = RigidBody2D.MODE_STATIC
room_positions.append(Vector3(room.position.x, room.position.y, 0))
From what I understand, if the room is randomly selected it will be deleted using queue_free() OR it will be appended to a room_positions for further processing. This means if I shift all the rooms to a different collision layer, the player/character instance would be alone with the TileMap on the same collision layer.
So I just added a simple room.collision_layer = 3 changing this section of the code to
for room in $Rooms.get_children():
if randf() < cull:
room.queue_free()
else:
room.mode = RigidBody2D.MODE_STATIC
room.collision_layer = 3
room_positions.append(Vector3(room.position.x, room.position.y, 0))
It doesn't seem to have changed anything, the player still spawns outside the room.
Do you see the rooms spread outwards?
You didn't write code to move the rooms. Sure, the code gives them a random position. But even if you set their position to Vector2.ZERO they move outwards, avoiding overlaps.
Why? Because these rooms are RigidBody2D, and they do push other physics objects. Such as other rooms or the player character.
That's the problem: These rooms are RigidBody2D, and you put your KinematicBody2D player character on top of one of them. The RigidBody2D pushes it out.
The tutorial you followed is exploiting this behavior of RigidBody2Ds to spread the rooms. However you don't need these RigidBody2D after you are done populating your TileMap.
Instead, you can store the start position in a variable for later placing the player character (you don't need offsets - by the way - the position of the room is the center of the room), and then remove the RigidBody2Ds. If you want to keep the code that writes the text, you would also have to modify it, so it does not fail when the room no longer exists.
Alternatively, you can edit their collision layer and mask so they don't collide with the player character (or anything for that matter, but why would you want these RigidBody2Ds that collide with nothing?).
Addendum post edit: Collision layers and mask don't work as you expect.
First of all, the collision layer and mask are flags. The values of the layers are powers of two (1, 2, 4, 8...). So, when you set it to 3, it is the layer 1 plus the layer 2. So it still collides with a collision mask of 1.
And second, even if you changed the collision layer of the rooms to 2 (so it does not match the collision mask of 1 that the player character has). The player character still has a layer 1 which match the collision mask of the rooms.
See also the proposal Make physics layers and masks logic simple and consistent.
Thus, you would need to change the layer and mask. Both. in such way that they don't collide. For example, you can set layer and mask to 0 (which disable all collisions). The algorithm that populates the TileMap does not use the layer and mask.
This is more of an open discussion topic than anything else. Currently I'm storing 50 Float32 values in my NSMutableArray *voltageArray before I refresh my CPTPlot *plot. Every time I obtain 50 values, I remove the previous 50 from the voltageArray and repeat the process....always displaying the 50 values in "real time" on my plot.
However, the data I'm receiving (which is voltage coming from a Cypress BLE module equipped with a pressure transducer) is so quick that any variation (0.4 V to 4.0 V; no pressure to lots of pressure) cannot be seen on my graph. It just shows up as a straight line, varying up and down without showing increased or decreased slopes.
To show overall change, I wanted to take those 50 values, store them in the first index of another NSMutableArray *stampArray and use the index of stampArray to display information. Meanwhile, the numberOfRecordsForPlot: method would look like this:
- (NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plotnumberOfRecords {
return (DATA_PER_STAMP * _stampCount);
}
This would initially be 50, then after 50 pieces of data are captured from the BLE module, _stampCount would increase by one, and the number of records for plot would increase by 50 (till about 2500-10000 range, then I'd refresh the whole the thing and restart the process.)
Is this the right approach? How would I be able to make the first 50 points stay on the graph, while building the next 50, etc.? Imagine an y = x^2 graph, and what the graph looks like when applying integration (the whole breaking the area under the curve into rectangles).
Look at the "Real Time Plot" demo in the Plot Gallery example app included with Core Plot. It starts off with an empty plot, adding a new point each cycle until reaching the maximum number of points. After that, one old point is removed for each new one added so the total number stays constant. The demo uses a timer to pass random data to the plot, but your app can of course collect data from anywhere. Be sure to always interact with the graph from the main thread.
I doubt you'll be able to display 10,000 data points on one plot (does your display have enough pixels to resolve that many points?). If not, you'll get much better drawing performance if you filter and/or smooth the data to remove some of the points before sending them to the plot.
Is it possible to create a Signal from a List? Essentially what I want is something with the signature List a -> Signal a. I know that a Signal represents a time-varying value and so something like this doesn't actually make any sense (i.e. I can't think of a reason to use it in production code).
I could see applications of it for testing though. For example, imagine some function which depended on the past values of a Signal (via foldp for instance) and you wanted to make assertions about the state of the system given the signal had received values x, y, and z.
Note that there wouldn't have to be anything special about the Signal denoting that it only would ever receive a fixed number of values. I'm thinking of it more like: in production you have a Signal of mouse clicks, and you want to test that from a given starting position, after a given set of clicks, the system should be in some other known state. I know you could simulate this by calling the function a fixed number of times and feeding the results back in with new values, I'm just wondering if it is possible.
I guess it's possible. You use a time-based signal, and map the values from the list over it:
import Time
import Graphics.Element exposing (show)
list = [1..10]
signalFromList : List a -> Signal a
signalFromList list =
let
(Just h) =
List.head list
time =
Time.every Time.second
maybeFlatMap =
flip Maybe.andThen
lists =
Signal.foldp (always <| maybeFlatMap List.tail) (Just list) time
in
Signal.filterMap (maybeFlatMap List.head) h lists
main = Signal.map show <| signalFromList list
However!
It shouldn't be hard to do testing without signals. If you have a foldp somewhere, in a test you can use List.foldl over a list [x,y,z] instead. That should give you the ability to look at the state of your program after inputs x, y, z.
I don't think there is any way it can be done synchronously in pure elm (Apanatshka's answer illustrates well how to set up a sequence of events across time and why it's a bad idea). If we look at how most Signals are defined, we'll see they all head down into a native package at some point.
The question then becomes: can we do this natively?
f : List a -> Signal a
I often think of (Signal a) as 'an a that changes over time'. Here we provide a List of as, and want the function to make it change over time for us.
Before we go any further, I recommend a quick look at Native/Signal.js: https://github.com/elm-lang/core/blob/master/src/Native/Signal.js
Let's say we get down to native land with our List of as. We want something a bit like Signal.constant, but with some extra behaviour that 'sends' each a afterwards. When can we do the sending, though? I am guessing we can't do it during the signal construction function, as we're still building the signal graph. This leaves us a couple of other options:
something heinous with setTimeout, scheduling the sending of each 'a' at an appropriate point in the future
engineering a hook into the elm runtime so that we can run an arbitrary callback at the point when the signal graph is fully constructed
To me at least, the former sounds error prone, and I hope the latter doesn't exist (and never does)!
For testing, your suggestion of using a List fold to mimic the behaviour of foldp would be the way I would go.