User:Darkfrei/example functions

1 Prints table
2 Draw grid
3 Draw mouse position
4 Beep
5 Point in area
6 Is value in list
7 Normalization and multiplication
8 Evaluate a point from any amount of control points
9 Split string with separator
10 Split string to list of symbols
11 Push rectangle from line
12 Easy vector math
13 Count vowels in the string
14 Reverse words, but not word sequence
15 Make snake matrix
16 Flatten deep list

Prints table

print('{' ..table.concat(line,",")..'},')

Draw grid

function draw_grid ()
	local grid_size = 20
	love.graphics.setLineWidth (1)
	love.graphics.setColor(0.25,0.25,0.25)
	local width, height = love.graphics.getDimensions( )
	for x = grid_size, width-1, grid_size do
		love.graphics.line(x, 0, x, height)
	end
	for y = grid_size, height-1, grid_size do
		love.graphics.line(0, y, width, y)
	end
end

Draw mouse position

function draw_mouse ()
	local mx, my = love.mouse.getPosition ()
	local text = mx..' '..my
	local font = love.graphics.getFont()
	local w = font:getWidth(text)
	local h = font:getHeight()
	love.graphics.setColor(0,0,0)
	love.graphics.rectangle('fill', mx, my-h, w, h)
	love.graphics.setColor(1,1,1)
	love.graphics.print(mx..' '..my,mx,my-h)
end

Beep

Define it:

local rate = 44100
local length = 1/32
local tone = 440 -- Hz
local p = math.floor(rate/tone) -- 128
local soundData = love.sound.newSoundData(length*rate, rate, 16, 1)
for i=0, length*rate-1 do soundData:setSample(i, i%p>p/2 and 1 or -1) end
local source = love.audio.newSource(soundData)
local function beep() source:play() end

Call it:

beep()

Point in area

function is_in_area (mx,my, x,y,w,h) -- mouse position and rectangle
	if (mx > x) and (mx < (x + w)) and
	   (my > y) and (my < (y + h)) then
		return true
	end
end

Is value in list

function is_value_in_list (value, list)
	for i, v in pairs (list) do
		if v == value then
			return true
		end
	end
end

Normalization and multiplication

Set magnitude to this vector:

function normul (x, y, factor) -- normalization and multiplication
	local d = (x*x+y*y)^0.5
	factor= factor or 1
	return factor*x/d, factor*y/d
end

Evaluate a point from any amount of control points

local function evaluate (curve, t)
	local ccpc = curve:getControlPointCount( )
	if ccpc > 1 then
		return curve:evaluate(t)
	elseif ccpc == 1 then
		return curve:getControlPoint(1)
	else
		return 0, 0
	end
end

Split string with separator

local function  split (string, separator)
	local tabl = {}
	for str in string.gmatch(string, "[^"..separator.."]+") do
		table.insert (tabl, str)
	end
	return tabl
end
--split ("123#456", "#") -- results: {"123", "456"}

Split string to list of symbols

local function  split2 (string)
	local tabl = {}
	string:gsub(".", function(c) table.insert(tabl, tonumber (c)) end)
	return tabl
end
--split2 ("123") -- results: {1, 2, 3}

Push rectangle from line

(made with chatGPT Feb 13 2023)

function pushRectOutOfLine(x, y, w, h, x1, y1, x2, y2)
  -- Вычисляем вектор направления линии
  local lineDirX = x2 - x1
  local lineDirY = y2 - y1
  
  -- Нормализуем вектор направления линии
  local lineLength = math.sqrt(lineDirX^2 + lineDirY^2)
  lineDirX = lineDirX / lineLength
  lineDirY = lineDirY / lineLength
  
  -- Вычисляем вектор от начальной точки линии до прямоугольника
  local toRectX = x - x1
  local toRectY = y - y1
  
  -- Проекция вектора от начальной точки линии до прямоугольника на вектор направления линии
  local dot = toRectX * lineDirX + toRectY * lineDirY
  
  -- Находим ближайшую точку на линии
  local nearestX, nearestY
  if dot <= 0 then
    nearestX, nearestY = x1, y1
  elseif dot >= lineLength then
    nearestX, nearestY = x2, y2
  else
    nearestX = x1 + dot * lineDirX
    nearestY = y1 + dot * lineDirY
  end
  
  -- Вычисляем вектор от ближайшей точки на линии до прямоугольника
  local toRectX = x - nearestX
  local toRectY = y - nearestY
  
  -- Если прямоугольник пересекает линию
  if math.abs(toRectX) < w/2 and math.abs(toRectY) < h/2 then
    -- Вычисляем вектор выталкивания
    local pushX = (w/2 - math.abs(toRectX)) * math.sign(toRectX)
    local pushY = (h/2 - math.abs(toRectY)) * math.sign(toRectY)
    
    -- Возвращаем вектор выталкивания и нормаль линии
    return pushX, pushY, lineDirX, lineDirY
  end
  
  return 0, 0, 0, 0
end

Short version:

function PushOutRectangleFromLine(x, y, w, h, x1, y1, x2, y2)
  local toRectX, toRectY = x - x1, y - y1
  local lineDirectionX, lineDirectionY = x2 - x1, y2 - y1
  local lineLength = math.sqrt(lineDirectionX^2 + lineDirectionY^2)
  lineDirectionX, lineDirectionY = lineDirectionX / lineLength, lineDirectionY / lineLength
  local dotProduct = toRectX * lineDirectionX + toRectY * lineDirectionY
  local closestPointX, closestPointY = x1 + dotProduct * lineDirectionX, y1 + dotProduct * lineDirectionY
  local distanceX, distanceY = x - closestPointX, y - closestPointY
  local intersectX, intersectY = closestPointX, closestPointY
  
  if dotProduct < 0 then
    intersectX, intersectY = x1, y1
    distanceX, distanceY = x - x1, y - y1
  elseif dotProduct > lineLength then
    intersectX, intersectY = x2, y2
    distanceX, distanceY = x - x2, y - y2
  end
  
  if math.abs(distanceX) < w / 2 and math.abs(distanceY) < h / 2 then
    local pushX, pushY = 0, 0
    
    if w / 2 - math.abs(distanceX) < h / 2 - math.abs(distanceY) then
      pushX = math.sign(distanceX) * (w / 2 - math.abs(distanceX))
    else
      pushY = math.sign(distanceY) * (h / 2 - math.abs(distanceY))
    end
    
    return pushX, pushY
  end
  
  return 0, 0
end

(fixed normal)

function PushOutRectangleFromLine(x, y, w, h, x1, y1, x2, y2)
    local toRectX, toRectY = x - x1, y - y1
    local lineLength = math.sqrt((x2 - x1) ^ 2 + (y2 - y1) ^ 2)
    local normalX, normalY = (y2 - y1) / lineLength, -(x2 - x1) / lineLength
    local dot = toRectX * normalX + toRectY * normalY
    local intersectX, intersectY = x - dot * normalX, y - dot * normalY

    if intersectX < x then
        intersectX = x
    elseif intersectX > x + w then
        intersectX = x + w
    end

    if intersectY < y then
        intersectY = y
    elseif intersectY > y + h then
        intersectY = y + h
    end

    local distance = (toRectX - intersectX) * normalX + (toRectY - intersectY) * normalY

    if distance < 0 then
        intersectX = intersectX + distance * normalX
        intersectY = intersectY + distance * normalY
    end

    return intersectX, intersectY, normalX, normalY
end

Easy vector math

-- Определение метатаблицы для векторов
local Vector = {}
Vector.__index = Vector

-- Конструктор вектора
function Vector.new(x, y)
  local v = {x = x or 0, y = y or 0}
  setmetatable(v, Vector)
  return v
end

-- Перегрузка оператора сложения
function Vector.__add(a, b)
  return Vector.new(a.x + b.x, a.y + b.y)
end

-- Перегрузка оператора вычитания
function Vector.__sub(a, b)
  return Vector.new(a.x - b.x, a.y - b.y)
end

-- Перегрузка оператора умножения на скаляр
function Vector.__mul(a, b)
  if type(a) == "number" then
    return Vector.new(b.x * a, b.y * a)
  elseif type(b) == "number" then
    return Vector.new(a.x * b, a.y * b)
  else
    error("Can only multiply vector by scalar.")
  end
end

-- Пример использования
local v1 = Vector.new(2, 3)
local v2 = Vector.new(4, 5)
local v3 = v1 + v2 -- v3 будет иметь координаты (6, 8)
local v4 = v1 - v2 -- v4 будет иметь координаты (-2, -2)
local v5 = v1 * 2 -- v5 будет иметь координаты (4, 6)
local v6 = 3 * v2 -- v6 будет иметь координаты (12, 15)


print (
	v1.x..' '..v1.y,
	v2.x..' '..v2.y,
	v3.x..' '..v3.y,
	v4.x..' '..v4.y,
	v5.x..' '..v5.y,
	v6.x..' '..v6.y
)

Count vowels in the string

Here is a function to count vowels in the string:

function countVowels(str)
  _, nvow = string.gsub(str, "[AEIOUaeiou]", "")
  return nvow
end
print(countVowels("hello world")) -- 3
print(countVowels("Lua is awesome")) -- 7
print(countVowels("fbwklfbwjf")) -- 0

Reverse words, but not word sequence

function reverseWord (str)
  local last = string.len (str)
  local res = ""
  for i = last, 1, -1 do
    res = res .. string.sub(str,i, i)
  end
  return res
end
function reverseWords (str)
  local text = ""
  for word in str:gmatch("%S+") do
    text = text .. ' ' .. reverseWord (word)
  end
  return text:sub(2, -1)
end
print(reverseWords("Hello world")) -- "olleH dlrow"
print(reverseWords("Lua is awesome")) -- "auL si emosewa"

Make snake matrix

as snakeMatrix (3) -- {{1, 2, 3}, {6, 5, 4}, {7, 8, 9}}

snakeMatrix (4) -- {{1, 2, 3, 4}, {8, 7, 6, 5}, {9, 10, 11, 12}, {16, 15, 14, 13}}

function snakeMatrix (n)
	local matrix = {}
	local index = 1
	for i = 1, n do
		local line = {}
		if i%2 == 1 then
			for j = 1, n do
				table.insert (line, index)
				index = index + 1
			end
		else
			for j = 1, n do
				table.insert (line, 1, index)
				index = index + 1
			end
		end
		matrix[i] = line
	end	
	return matrix
end

function showDeepList (tabl)
	local list = {}
	if type(tabl[1]) == "table" then
		for i = 1, #tabl do
			table.insert (list, showDeepList (tabl[i]))
		end
	else
		list = tabl
	end
	return '{'.. table.concat (list, ', ') ..'}'
end

print (showDeepList(snakeMatrix (3))) -- {{1, 2, 3}, {6, 5, 4}, {7, 8, 9}}
print (showDeepList(snakeMatrix (4))) -- {{1, 2, 3, 4}, {8, 7, 6, 5}, {9, 10, 11, 12}, {16, 15, 14, 13}}

Flatten deep list

function deepFlatten (list, tabl)
	for i, v in ipairs (tabl) do
		if type (v) == "table" then
			deepFlatten (list, v)
		else
			table.insert (list, v)
		end
	end
end

function flatten (tabl)
	local list = {}
	deepFlatten (list, tabl)
	return list
end

local t = {1, 2, {3, 4, {5, 6}, 7}, 8}
print(table.concat(flatten(t), ", ")) -- "1, 2, 3, 4, 5, 6, 7, 8"

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