Hello i have the following lua code which functionality is to rotate a point creating a circle. The problem I'm having is with initial and/or last state. Since there is a clock running whenever i stop the rotation and start again, the point jumps around. I tried saving the last value after the lfo is turned off, and then use this value in each sin and cos functions but i cannot make it work well.
Thank you!
The Code:
local last = 0
local trigger = false
function update()
t = getMillis()
T = 3000
if trigger == true then
x = math.cos(2*math.pi*( (t - last) + t) /T)
y = math.sin(2*math.pi*( (t - last) + t) /T)
end
end
function onValueChanged(key)
if key == "x" and self.values.x == 1 then
if trigger == true then
last = t
end
trigger = not trigger
end
end
Related
I am in the process of learning Julia and I'd like to do some buffer manipulation.
What I want to achieve is the following:
I've got a buffer that I can write to and read from at the same time, meaning that the speed with which I add a value to the Fifo buffer approximately equals the speed with which I read from the buffer. Reading and writing will happen in separate threads so it can occur simultaneously.
Additionally, I want to be able to control the values that I write into the buffer based on user input. For now, this is just a simple console prompt asking for a number, which I then want to write into the stream continously. The prompt refreshes and asks for a new number to write into the stream, but the prompt is non-blocking, meaning that in the background, the old number is written to the buffer until I enter a new number, which is then written to the buffer continuously.
This is my preliminary code for simulatenous reading and writing of the stream:
using Causal
CreateBuffer(size...) = Buffer{Fifo}(Float32, size...)
function writetobuffer(buf::Buffer, n::Float32)
while !isfull(buf)
write!(buf, fill(n, 2, 1))
end
end
function readfrombuffer(buf::Buffer)
while true
while !isempty(buf)
#show read(buf)
end
end
end
n_channels = 2
sampling_rate = 8192
duration = 2
n_frames = sampling_rate * duration
sbuffer = CreateBuffer(n_channels, n_frames)
print("Please enter a number: ")
n = parse(Float32, readline())
s1 = Threads.#spawn writetobuffer(sbuffer, n)
s2 = Threads.#spawn readfrombuffer(sbuffer)
s1 = fetch(s1)
s2 = fetch(s2)
I am not sure how to integrate the user input in a way that it keeps writing and reading the latest number the user put in. I looked at the documentation for channels, but didn't manage to get it working in a way that was non-blocking for the stream writing. I don't know that the correct approach is (channels, events, julia's multithreading) to enable this functionality.
How would I go on about to include this?
I managed to get it working, but I think it could be improved:
using Causal
CreateBuffer(size...) = Buffer{Fifo}(Float32, size...)
function writeToBuffer(buf::Buffer, n::Float32)
write!(buf, fill(n, 2, 1))
end
function readFromBuffer()
global soundbuffer
println("Starting")
sleep(0.5)
while true
while !isempty(soundbuffer)
read(soundbuffer)
end
end
println("Exiting...")
end
function askForInput()::Float32
print("Please enter a number: ")
a = parse(Float32, readline())
return(a)
end
function inputAndWrite()
global soundbuffer
old_num::Float32 = 440
new_num::Float32 = 440
while true
#async new_num = askForInput()
while (new_num == old_num)
writeToBuffer(soundbuffer, new_num)
end
old_num = new_num
println("Next iteration with number " * string(new_num))
end
end
n_channels = 2
sampling_rate = 8192
duration = 2
n_frames = sampling_rate * duration
soundbuffer = CreateBuffer(n_channels, n_frames)
s1 = Threads.#spawn inputAndWrite()
s2 = Threads.#spawn readFromBuffer()
s1 = fetch(s1)
s2 = fetch(s2)
I have an object, when it reaches a threshold, it will enter a silence period, which I use a parameter (I call it ode_status) flipping between 1 and 0 to determine whether performing the ODE or not.
The threshold is implemented by ContinuousCallback.
fucntion condition(u, t, integrator)
u[1] - threshold
end
function affect!(integrator)
integrator.p[1] = 0 # integrator.p[1] represents ode_status
flip_back_time[1] = integrator.t + 5 # define silence period = 5s
end
ContinuousCallback(condition, affect!)
Next, I want to flip back ode_status after 5s, so I use DiscreteCallback.
function condition(u, t, integrator)
integrator.p[1] == 0 &&
integrator.t >= flip_back_time[1]
end
function affect!(integrator)
integrator.p[1] = 1
end
DiscreteCallback(condition, affect!)
However, the result is not what I think. The time that ode_status flips back is not exactly after 5s. It is at 5.107... or 5.879 in another trial.
I think I misuse these callback functions. Would anyone tell me how to solve this? Thanks in advance!
This is because the next step is not exactly at the 5 seconds later time. Remember, DiscreteCallback fires only at step times, so you need to insert a tstop to tell it to stop exactly 5 seconds in the future.
function affect!(integrator)
integrator.p[1] = 0 # integrator.p[1] represents ode_status
flip_back_time[1] = integrator.t + 5 # define silence period = 5s
add_tstop!(integrator,integrator.t + 5)
end
UPDATE -- I figured it out. Turns out I am bad at math and visualizing 2d points. I wasn't setting south or east subdivisions correctly.
I have been trying to make a quadtree to track points in Love2d. I have the most of the code written, but I don't think the recursion is working properly.
I'm pretty new to the coding scene, so I really don't know where to start.
It seems to leave out points that go into the southeast quadrant.
I think as it goes recursively into the insert function it either looks at the parents point array or doesn't seem to go into all the insert functions.
local QuadTree = {}
QuadTree.__index = QuadTree
function QuadTree:new(boundary,capacity)
local quadTemp = {}
setmetatable(quadTemp, QuadTree)
if (not boundary) then
print('No boundary given to new QuadTree')
end
if (type(capacity) ~= 'number') then
print('Boundary should be a number')
end
if (capacity < 1) then
print('capacity should be greater than one')
end
quadTemp.boundary = boundary
quadTemp.capacity = capacity
quadTemp.points = {}
quadTemp.hasDivided = false
return quadTemp
end
function QuadTree:insert(p)
--If this point doesnt belong in this spot dont add it
if (not self.boundary:contains(p)) then
return false
elseif (#self.points<self.capacity) then
table.insert(self.points,p)
return true
elseif(not self.hasDivided) then
self:subdivide()
elseif(self.hasDivided) then
return self.northeast:insert(p) or
self.northwest:insert(p) or
self.southeast:insert(p) or
self.southwest:insert(p)
end
end
function QuadTree:subdivide()
local x = self.boundary.xpos
local y = self.boundary.ypos
local w = self.boundary.width / 2
local h = self.boundary.height / 2
local nw = Rectangle:new(x,y,w,h)
self.northwest = QuadTree:new(nw,self.capacity)
local ne = Rectangle:new(w,y,w,h)
self.northeast = QuadTree:new(ne,self.capacity)
local sw = Rectangle:new(x,h,w,h)
self.southwest = QuadTree:new(sw,self.capacity)
local se = Rectangle:new(w,h,w,h)
self.southeast = QuadTree:new(se,self.capacity)
self.hasDivided = true
end
function QuadTree:query(range,found)
--If we havent found any yet lets create a list incase we do
if (not found) then found = {} end
--If this cell doesnt contain the boundary then return an empty list
if (not range:intersects(self.boundary)) then
return found
end
for k,v in pairs(self.points) do
if (range:contains(v)) then
table.insert(found,v)
end
end
--If the current cell has divided we need to check its children
if (self.hasDivided) then
self.northwest:query(range,found)
self.northeast:query(range,found)
self.southwest:query(range,found)
self.southeast:query(range,found)
end
return found;
end
Edit: This question is about Roblox Lua.
I'm using math.sin(tick()) to get a variable number and would like for it to always start at 0. Is this possible using math.sin? Is there something else I can use other than tick() to make this work?
Example:
for i = 1, 10 do
local a = math.sin(tick())+1
print(a)
wait()
end
wait(1)
for i = 1, 10 do
local a = math.sin(tick())+1
print(a)
wait()
end
My goal is to have this number start at 0 every time and then increase from there. So, it would start at 0 then increase to 2 and then decrease back to zero and continue modulating between 0 and 2 for as long as I continue calling it. Using the example above the number starts at any arbitrary number between 0 and 2.
I took a different approach and came up with this. It does exactly what I wanted to do with math.sin(tick()). If anyone knows other ways to accomplish this I would like to know.
local n = 0
local m = 0
local Debounce = true
local function SmoothStep(num)
return num * num * (3 - 2 * num)
end
while Debounce do
for i = 1, 100 do
wait()
m = m+.01
n = SmoothStep(m)
print(n)
if not Debounce then break end
end
for i = 1, 100 do
wait()
m = m+.01
n = SmoothStep(m)
print(n)
if not Debounce then break end
end
end
To non-Roblox users: tick() returns the local UNIX time. wait(t) yields the current thread for t seconds, the smallest possible interval being roughly 1/30th of a second.
Given that math.sin(0) equals 0, what you have to do is subtract the tick() inside the loop with the time the loop began at. This should make the expression inside math.sin start at roughly 0 at the beginning of the loop.
local loopstart = tick()
for i = 1, 10 do
local a = math.sin(tick() - loopstart)+1
print(a)
wait()
end
Ok, first up, this is NOT for a class, test, or other student type activity.
I'm a scripter for a game, and am trying to implement the math library for all to use, and unfortunately, all I have available to me is very basic lua. The implemented version cannot be changed, and does not include any libraries. For those wondering, its for scripting in Fold.It.
Here's what I have...
math={}
math.fact = function(b) if(b==1)or(b==0) then return 1 end e=1 for c=b,1,-1 do e=e*c end return e end
math.pow = function(b,p) e=b if(p==0) then return 1 end if(p<0) then p=p*(-1) end for c=p,2,-1 do e=e*b end return e end
math.cos = function(b,p) e=0 p=p or 10 for i=1,p do e=e+(math.pow(-1,i)*math.pow(b,2*i)/math.fact(2*i)) end return e end
To clarify above, math.fact returns factorial, which is returning accurate to about 10 points of precision, and is a new function I've done to aid in cosine calculation.
The math.pow is also a new function to handle returning powers, also working as expected.
The issue is with the cosine function. Its returning unexpected values. Here's an easier to digest version (I've been writing my library stuff ultra lean)...
function math.cos(value,precision)
result=0
precision=precision or 10
for i=1,precision do
result=result+(math.pow(-1,i)*math.pow(value,2*i)/math.fact(2*i))
end
return e
end
The problem is, with those functions, for print(math.cos(90)) it returns 4.77135... when I'm expecting -0.44807... (based on calc in scientific mode, or using an online tool to cos(90)).
I'm also having issues with sin and tan, however they are similarly written to cos, which seems to have been done in many languages. If I can figure out what I'm doing wrong, I can get them all fixed.
EDIT: Corrected typo
First, your lua doesn't run. Second, you need to make your variables local. Third, cosine starts with a one.
The problem is because the Taylor series you are using only converges on the correct values of cosine close to zero. You would have to use a far more terms of the series to get it to handle 90 correctly. You can fix this for your implementation two ways:
Add a pi constant. Then use a while loop to adjust the value such that abs(value) < 2*pi:
math.pi = 3.14159265358
while value > math.pi*2 do
value = value - math.pi * 2
end
while value < -math.pi*2 do
value = value + math.pi * 2
end
Or - find or implement a version of fmod in lua.
Here is the corrected code (you can minify it):
math={}
math.fact = function(b)
if(b==1)or(b==0) then
return 1
end
local e=1
for c=b,1,-1 do
e=e*c
end
return e
end
math.pow = function(b,p)
local e=b
if(p==0) then
return 1
end
if(p<0) then
p=p*(-1)
end
for c=p,2,-1 do
e=e*b
end
return e
end
math.cos = function(b,p)
local e=1
b = math.correctRadians(b)
p=p or 10
for i=1,p do
e=e+(math.pow(-1,i)*math.pow(b,2*i)/math.fact(2*i))
end
return e
end
math.pi = 3.1415926545358
math.correctRadians = function( value )
while value > math.pi*2 do
value = value - math.pi * 2
end
while value < -math.pi*2 do
value = value + math.pi * 2
end
return value
end
interactive lua run:
imac:~ root$ lua -i temp.lua
Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio
> print( math.cos( 90 ) )
-0.44807359244883
>