Roblox sword nine sword two

Roblox Sword two of sword nine 【 Sword of imperial code 】

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Preface

Blogger Yu 2020 Year into the pit UGC Game development , So far, a number of UGC works , Such as power crisis 、 The scourge of the heroic expedition 、 Reign of Swords 、 Versatile millionaire …… so to speak UGC Game development is a new outlet for entrepreneurship . Just like today's low code , Easy to use , More production , Quick results .

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This blog mainly takes you to break through LUA This scripting language - With Roblox For example .

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One 、 Learning route

• Picture form

Two 、Lua Basics

   As far as we know UGC Game creation platform 【 Restart the world -Reworld】、【Roblox】 Both use Lua This scripting language UGC Game Programming . Bloggers' first object-oriented language is C#, Mainly for GIS Development service . Later I met UGC Game development , Learned auxiliary language -Lua,Lua This scripting language may be unheard of by many people , But this powerful Glue language It's really around us , Take games for example

• It's all right with C/C++、C#、Java Interact perfectly
• Definition 、 Store and manage basic game data
• Create and maintain a developer friendly game storage and loading system
• Create functional prototypes , It can be ported with high-performance language later
• Playing games Hot update operation 【 namely Patch , Commonly used 】
  

1、Lua Introduce

Lua It's a kind of Lightweight and compact Of Scripting language , It consists of standard C Language Write and be Open source , It can be very convenient And other procedures Conduct Integrate and Expand （C#,Java…）, It is designed to Embedded applications in , Flexible extension and customization for applications .

1.1 Explanatory language

Lua It's script language , Scripting language yes Explanatory language One of them . Classification for programming languages , There are different types of classification from different angles . among Compiler language and Explanatory language Mainly with How to execute the program And classification . For specific differences between the two, please refer to Poke me
Simply speaking

• Interpretive language is The interpreter executes while interpreting Program , No Generate Executable file .
• Compiled languages are The compiler compiles before executing Program , Generate Executable file , can repeat function Executable file .

2、Lua characteristic

• Support process oriented programming and Functional programming
• Automatic memory management , Only one generic type of surface （table）, But it can be done Array , Hashtable , aggregate , object .
• Language built-in matching pattern .
• Closure （closure）.
• A function can also be regarded as a value .
• Provide Multithreading （ coroutines , Not a thread supported by the operating system ）.
• adopt Closure and table Can easily support object-oriented Some of the key mechanisms needed for editing , such as Data abstraction , Virtual functions , Inherit and heavy load etc. .

3、Lua Data type of

3.1 data type

Lua There are eight main data types in , Namely nil、boolean、number、string、function（ Functional programming ）、table、thread、userdata.

data type	describe
nil	This is the easiest one , Only value nil Belong to this class , It means a Invalid value （ stay Conditional expression Equivalent to false）.
boolean	Contains two values ：false and true.
number	Express Double precision type real floating point number
string	The string consists of A pair of double or single quotation marks To express
function	from C or Lua Functions written
userdata	Represents any... Stored in a variable C data structure
thread	Represents an independent line of execution , be used for Execute the collaboration program
table	Lua In the table （table） It's actually a " Associative array "（associative arrays）, Array Of Indexes It can be Numbers 、 character string or Table type . stay Lua in ,table Is created by " Construct expression " To complete , The simplest construction expression is {}, To create an empty table .

Example

print(type("Hello world"))      --> string
print(type(10.4*3))             --> number
print(type(print))              --> function
print(type(type))               --> function
print(type(true))               --> boolean
print(type(nil))                --> nil
print(type(type(X)))            --> string

3.2 Lua Variable

3.2.1 Variable type

Lua The variables are 3 Types

• Global variables
• local variable （local）
• Fields in table

3.2.2 Variable Convention

• Lua All in Variables are all global variables , Even if it is It is also a global variable in the function body , Unless use local keyword Explicitly declared as local variable , local variable The scope of is From the declaration to the end of the statement block . In short , If not local Declarative , It's all global variables .【 a key 】
• Variables before use , A statement must be made
• Variable The default value is zero nil
• Lua It can be applied to multiple variables simultaneous assignment , Variable list and List of values Need to use comma separate
• Lua Language support Direct assignment and There is no need to declare a data type The operation of .

Example

val = 10          -- Global variables 
local locVal = 10  -- local variable 

function value1()
    c = 20
    local d = 10
end

value1()
print(val, locVal, c, d)   -- After executing the function   The value of a local variable cannot be printed , Global variables can 

do
    local val = 4          -- Defining local variables val
    locVal = 5             -- Reassign a local variable 
    print(val, locVal)     -- Print do Internal val = 4 as well as locVal = 5
end

print(val, locVal)         -- there val Global variable val,locVal For the local variable to be re assigned locVal
-- Multiple variables are assigned at the same time 
a, b = 10, 2*x  -- a=10; b=2*x 

• Add Note writing

-- Single-line comments 
 perhaps 
--[[  Multiline comment  --]]

4、 Control statement

4.1 Branch statement

if( Boolean expression ) then
   --[  The Boolean expression is  true  When the statement block is executed  --]
else
   --[  The Boolean expression is  false  When the statement block is executed  --]
end

4.2 Loop statement

Type of cycle	describe
while	The cycle is Condition is true when , Let the program Repeat Some statements . Before executing the statement, check whether the condition is true.
for	loop Repeat the specified statement , repeat frequency Can be found in for In the sentence control .
repeat…until	Repeat the loop , until designated Conditions by really When is stop

4.2.1 while loop

while(condition)do
   < Executor >
end

4.2.2 for loop

1） The number for loop

for var=exp1,exp2,exp3 do  
    < Executor >  
end

• var from exp1 Change to exp2, Every time you change it exp3 Step length Increasing var, and Do it once ” Executor ”.
• exp3 It's optional , If you don't specify , The default is 1.

2） Generic for loop

notes Game development Commonly used
Generic for The loop iterates through all the values through an iterator function , similar java Medium foreach sentence .

-- Print array a All values  
for k,v in ipairs(a) do 
     print(v) 
end

Briefly ,k,v by Key value pair ,k yes Index value ,v yes The element value corresponding to the index .

4.2.3 repeat…until loop

Do it first , Then judge the conditions

repeat
   < Executor >
while(condition)

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Loop control statement

• break   Exit the current loop or statement , The script starts to execute The following statement .
  lua There is no continue key word
• In disguise continue

 
for i = 1, 100 do
    while true do
        if i % 2 == 1 then break end
 
        --  There's a lot of code here 
        --
        --
        break
    end
end
 

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4.3 function

optional_ overall situation / Local  function  Function name (argument1, argument2, argument3..., argumentn)
    The body of the function 
 return  Function return value 
end

• Lua A function can Return multiple result values , stay return After listing the list of values to be returned, you can return multiple values , Such as return m, mi
• Lua The function can accept Variable parameters , and C The language is similar to that used in function parameter lists Three points （…) Indicates that a function has variable arguments ,Lua Put the parameters of the function in a place called arg In the table of ,#arg It means incoming Parameters Of Number

Two 、Lua Table of （table）

1、table Introduction to

surface (Table) yes Lua In language Most importantly ( In fact, it is only Of ) And powerful data structure .
Use table ,Lua Language can be expressed in a simple 、 Express in a unified and efficient way Array 、 aggregate 、 Record and Many other data structures .
Lua Language is also used surface To express package ( package ) and Other objects .
Lua The table in language is essentially an auxiliary array ( associative array ), This kind of array can not only use The number As index , You can also use character string or Any other type of value As Indexes (nil With the exception of ).
Values stored in the same table can have different type indexes , And you can press Demand grows to accommodate new elements

Example
When a function is called math.sin when , We might think so “ Called math Functions in the library sin”;
And for Lua language , Its actual meaning is “ In string "sin" Search the table for the key math”.

2、table Use

2.1 initialization

1、
local a = {
    }
2、
local a = {
    ["x"] = 12,["mutou"] = 99,[3] = "hello"}
print(a["x"])
3、
local a = {
    x=12,mutou=99,[3]="hello"}
print(a["x"])
4、
local a = {
    x=12,mutou=99,[3]="hello"}
print(a.x)
 notes ：
1 Initialize for empty table ,2 General operations for initializing and assigning initial values （ Use [] For index , Use = Associate an index with a value ）
3 and 4 Indexing is a concise way of writing strings 


 Default numeric index （ List constructor ）
local a ={
    [1]=12,[2]=43,[3]=45,[4]=90}
 Concise Edition   local a = {
    12,43,45,90}
print(a[1])

• Use List constructor when , The default index is from 1 Start （ instead of 0）, And so on . This is different from other languages .
• No, give Indexes Of , from Table Auto give Digital index

2.2 operation

2.2.1 Access elements

a key
Use . This grammar is followed by String index value or [ Index value ] Can access table The index of corresponds to Element value
notes ：table For the length of the # Table name To said

local a = {
    
{
    x = 1,y=2},
{
    x = 3,y = 10}
}
print(a[1].x)
print(#a)

Add   in pairs and in ipairs The difference between

in pairs The method is more general , Don't overemphasize table Medium key value 
in iparis The method emphasizes table Of key The values are in order , When the sequence is interrupted ,for Cycle termination 

2.2.2 Insert

Use table.insert() Method

tab2 = {
    "a",2,"b",5} -- Define a table

table.insert(tab2,2,"king")  -- Specifies that a value is inserted at a certain location 
for i, v in ipairs(tab2) do
   -- print(v)  -- Output a king 2 b 5
end

table.insert(tab2,3)  -- If there is no designated location , By default, the value is inserted at the end position 
for i, v in ipairs(tab2) do
   -- print(v)  -- Output a king 2 b 5 3
end

tab3 = {
    "d",7,"e"}
table.insert(tab2,tab3) --  take table Insert table
for i, v in ipairs(tab2[7]) do
    --print(v)  -- Output d 7 e
end

tab2["mm"]="mmm"   -- Add a new key value pair    Below for Iterator selection pairs To traverse the new key value pair , Instead of ipairs
for i, v in pairs(tab2) do
    print(i,v)  -- Output 1 a ; 2 king ; 3 2 ; 4 b ; 5 5 ; 6 3 ; 7 table ;mm mmm
end

2.2.3 Delete

Use table.remove() Method

tab4 = {
    1,4,"tt","jj"}

table.remove(tab4,1) -- Removes the from the specified location table value , If no location is specified , The last element is removed by default 

for i, v in ipairs(tab4) do
    print(v)  -- Output  4 tt jj
end

2.2.4 to update

visit The element corresponding to the index and assignment that will do

2.2.5 Sort

Use table.sort() Method

language = {
    "lua","java","c#","c++"}

table.sort(language) -- Only table One parameter , Use lua The default sort method is sort 
for i, v in ipairs(language) do
   -- print(v) -- Output c# c++ java lua
end

local function my_comp1(element1,element2)  -- Custom comparison function   As table.sort() Parameters 
    return element1<element2
end
table.sort(language,my_comp1)
for i, v in ipairs(language) do
    print(v)   -- Output  c# c++ java lua
end


local function my_comp2(element1,element2)  -- Custom comparison function   As table.sort() Parameters 
    return element1>element2
end
table.sort(language,my_comp2)
for i, v in ipairs(language) do
   -- print(v) -- Output lua java c++ c#
end


local function my_comp3(element1,element2)  -- Custom comparison function   As table.sort() Parameters 
    if element1==nil then
        return false
    end
    if element2==nil then
        return true
    end
    return element1>element2
end
language[2]=nil   --table There is nil Existing situation 
table.sort(language,my_comp3)
for i, v in ipairs(language) do
   -- print(v) -- Output lua c++ c#
end

2.2.6 Remove the contents of the entire table

• Multiple table names can be referenced to the same table , When the last reference is released , The garbage collector will eventually delete the table .
• Set the table to nil, Then wait for garbage collection or enforce a garbage collection （collectgarbage）.
• in other words , In program development , Need to put The table is empty Come on Free table resources .
• If Do not want to empty , You can try weak table Use , Need to use Tuples The concept of

local table = {
    1,1,1,1,1,1,11,1,1}
--1. This method is more violent , Direct will table empty 
table = {
    }  perhaps  table=nil     -- Release table References to 
print（#table） 				--- nil
--2. Remove the entire by traversing the loop table Elements in 
for i = #table ,table do 
	table.remove(table,i)
	i = i - 1
end
-- Be careful ： Removing table When the elements in ,table The elements in the will be filled automatically , So remove all from the last bit 

3、 ... and 、 Meta table Introduction

1、 Meta table Introduction

Lua Of surface The essence is actually a similar HashMap Things that are , There are many elements Key-Value Yes , If you try to visit In a table Elements that do not exist when , It will trigger Lua A set of Search mechanism , This mechanism is also used to simulate similar “ Inherit ” act
 
A meta table is like a “ Operation guide ”, It contains a series of Operational solutions , for example __index Method It defines this surface stay Index failed What to do in case of .
 
The method to set the meta table is setmetatable(son, father) -- hold son Of metatable( Metatable ) Set to father
 
The key word is setmetatable

1.1 Lua Rules for finding elements in a table

• Find in table , If you find , Return the element , If you can't find it, continue
• . Judge whether the table has meta table , If there is no meta table , return nil, If there is a meta table, continue
• Judge whether the meta table has __index Method , If __index Method is nil, Then return to nil; If __index The method is a surface , be repeat 1、2、3; If __index The method is a function , Then return to The return value of this function

2、 object-oriented

Three characteristics of object-oriented

• encapsulation
• Inherit
• polymorphic

Detailed introduction can be moved step by step Java The sword opens the gate of heaven （ Two ）

Lua Object oriented is not supported , But it can be used Metatable Realization object-oriented

2.1 Official practice

• Class definition
  • The method is generally : This grammar sugar means
  • self Refer to oneself

    local Class= {
     value=0 }   -- Defining attributes 

    function  Class:new(o)   -- Definition new Method , The template can be modified 
         o=o or {
    };
         setmetatable(o,self);  -- take self Set to o The yuan table of 
         self.__index=self;     -- Point to your 
         return o;
    end

    function  Class:showmsg()   -- Define methods 
        print(self.value);
    end

    local  test = Class:new();   -- Class instantiation 
    test:showmsg();   -- Method call 

• Class inheritance

    local  A = Class:new();      -- class A Definition 

    function  A:new(o)     -- new Method , The template may not be modified 
          local  o = o or {
    };
          setmetatable(o,self);
          self.__index=self;
          return o;
    end
    function  A:showmsg(  )   -- Common method 
        print (self.value);   -- Properties of the parent class 
        print("zhishi  Test ah ah  ")
    end

    local  s = A:new({
    value=100});   -- class A initialization 
    s:showmsg();    -- Method call 

2.2 Elegant way

class.lua file 
--[[  Simulate the base class of inheritance structure  ]]
local _class = {
    }
 
function Class(super)
    local class_type = {
    }
    class_type.ctor = false            -- Constructors 
    class_type.super = super           -- Inherit 
    class_type.New = function(...)     -- example 
        local obj = {
    }
        do
            local create               -- Create closure functions 
            create = function(c, ...)
                if c.super then        -- There is a parent class , Recursive create 
                    create(c.super, ...)
                end
                if c.ctor then
                    c.ctor(obj, ...)   -- Constructors 
                end
            end
 
            create(class_type, ...)    -- Closure function entry 
        end
 
        setmetatable(obj, {
    __index = _class[class_type]})    -- Look up meta table 
 
        return obj
    end
 
    local vtbl = {
    }                      -- A temporary table 
    _class[class_type] = vtbl            -- Member variable assignment 
 
    setmetatable(                        -- assignment 、 Look up meta table （vtbl Find and assign ）
        class_type,
        {
    
            __newindex = function(t, k, v)
                vtbl[k] = v
            end,
            --For call parent method
            __index = vtbl
        }
    )
 
    if super then                        -- Inheritance lookup meta table (vtbl assignment , Returns the parent class value )
        setmetatable(
            vtbl,
            {
    
                __index = function(t, k)
                    local ret = _class[super][k]
                    vtbl[k] = ret
                    return ret
                end
            }
        )
    end
 
    return class_type
end

-------- Use 

-- Of course, call class.lua file 
base=Class()       --  Define a base class  base_type
function base:ctor(x)  --  Definition  base_type  Constructor for 

    print("base ctor")

    self.x=x

end
function base:print_x()    --  Define a member function  base:print_x

    print(self.x)

end
function base:hello()  --  Define another member function  base:hello

    print("hello base")

end



-- Subclass implementation 
child=Class(base);
function child:ctor()
    print("child ctor");
end

function child:hello()
     print("hello child")
end


-- call 
 local a=child.New(21);
 a:print_x();
 a:hello();

Both methods have advantages and disadvantages

• Bloggers use The second kind The way , The second method is not different from object-oriented programming .

• local Variable is to create a new variable , Obey the rule that the child scope overrides the parent scope .

• Especially for require "modname" Module in , At the time of writing , You cannot use global variables directly , Because the same variable will save its variable state and affect other uses . The best way to deal with it is to rely on the input as much as possible , Function internal definition local Variables, etc .

• local Faster access ( as a result of local Variables are stored in lua Inside the stack of is array operation , The global variables are stored in _G Medium table in , Less efficient than the stack )

• Encapsulation is possible , but Inconvenient to embed In this code , So we ignore encapsulation Of Deep meaning , stay Lua in , Encapsulation is simply understood as attribute and Method Put it all together .

Four 、UGC Platform and Lua The combination of development

1、 Client script

The client program is written in the client script , The main functions of the program are Submit data , Players will use the device to Input , Like clicking on a button 、 Click the mouse, etc , Client program Get the player's input data After simple treatment Submit to server .
Client script The only parts created are Local players only Can see Of .

• With Roblox For example ,LocalScript Is used when connecting to Roblox On the client side of the server Lua Code Lua Source container .

2、 Server scripts

The server code is written in the server script , The main functions of the program are Analyze and process these data , And then put The processing result is returned to the client for display . 
Server scripts The part created is All players all Can see Of .

image UGC Every game developed in the game development platform , The platform will allocate corresponding Server capacity .

• With Roblox For example ,Script（ Script ） It's a kind of Lua Code container , Its contents can be run on the server .

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• Server scripts and client-side scripts can be accessed through RemoteEvent、 Event object And other different communication mechanisms on different platforms signal communication

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3、 Modular development

In the development of large projects , We adopt a divide and conquer strategy , Divide large projects into small modules , Interfaces are reserved between small modules , After integration, the project will be formed .
stay UGC Platform development games , Modularity is mainly reflected in the following two aspects

• Use Object oriented programming idea Carry out engineering development
• Use General module One by one Module writing , for Client or server Script call 【 The key word is require, Common module scripts all Can be called by client and server scripts 】

With Roblox For example , Sure ModuleScript this Lua Source container , It only runs once , And must return the same value .

And then in ModuleScript As a unique parameter , By calling require Return this value .

In the opinion of bloggers , The module can be divided into client and server modules

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Client module

• routine UI Input 【 Send a request 】
• Local scene configuration
• The local store
• Local logic

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Server scripts

• General tools
• Server storage
• Controller forward 【 Receiving request 】
• Service Business logic
• Mapper Data persistence

5、 ... and 、 Conclusion

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//                          _ooOoo_                               //
//                         o8888888o                              //
//                         88" . "88                              //
//                         (| ^_^ |)                              //
//                         O\  =  /O                              //
//                      ____/`---'\____ //
//                    .'  \\|     |//  `.                         //
//                   /  \\|||  :  |||//  \                        //
//                  /  _||||| -:- |||||-  \                       //
//                  |   | \\\  -  /// |   |                       //
//                  | \_|  ''\---/'' | | //
//                  \  .-\__  `-`  ___/-. /                       //
//                ___`. .'  /--.--\ `. . ___ //
//              ."" '< `.___\_<|>_/___.'  >'"".                  //
//            | | :  `- \`.;`\ _ /`;.`/ - ` : | |                 //
//            \  \ `-.   \_ __\ /__ _/   .-` /  /                 //
//      ========`-.____`-.___\_____/___.-`____.-'========         //
//                           `=---=' //
//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        //
//             The Buddha bless         Never goes down       never BUG                    //
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