Frictional Game Wiki

<h1>Script</h1> <div class="level1"> </div> <h2>Code style</h2> <div class="level2"> <p> The following is an overview of how the code should look like. For anybody working for Frictional Games, this is a must. For all else, see it as guidelines to have consistent code which is especially good if you want share your stuff. </p> <p> Remember also to look at existing code and try and copy the looks. </p> </div> <h3>Prefixes</h3> <div class="level3"> <p> System Hungarian notation is to be used for all variable names. These are the notations used: </p> <span class='np_break'> </span> <div class="table"><table class="inline"> <tr class="row0"> <td class="col0" colspan="2"><b>Prefix</b></td><td class="col2" colspan="2"> <b>Description</b></td><td class="col4" colspan="2"> <b>Example</b> </td> </tr> <tr class="row1"> <td class="col0" colspan="2">c</td><td class="col2" colspan="2"> a class </td><td class="col4" colspan="2"> class cMyClass {}</td> </tr> <tr class="row2"> <td class="col0" colspan="2">i</td><td class="col2" colspan="2"> an interface </td><td class="col4" colspan="2"> interface iMyInterface {}</td> </tr> <tr class="row3"> <td class="col0" colspan="2">f</td><td class="col2" colspan="2"> a float or double value.</td><td class="col4" colspan="2"> float fX;</td> </tr> <tr class="row4"> <td class="col0" colspan="2">l</td><td class="col2" colspan="2"> any integer (char, int, uint, etc)</td><td class="col4" colspan="2"> int lX;</td> </tr> <tr class="row5"> <td class="col0" colspan="2">p</td><td class="col2" colspan="2"> an angel script handle </td><td class="col4" colspan="2"> iPhysicsBody@ pBody;</td> </tr> <tr class="row6"> <td class="col0" colspan="2">s</td><td class="col2" colspan="2"> a string </td><td class="col4" colspan="2"> cString sWord;</td> </tr> <tr class="row7"> <td class="col0" colspan="2">v</td><td class="col2" colspan="2"> a vector or array </td><td class="col4" colspan="2"> int[] vNumbers; cVector3f vPoint</td> </tr> <tr class="row8"> <td class="col0" colspan="2">mtx</td><td class="col2" colspan="2"> a matrix</td><td class="col4" colspan="2"> cMatrixf mtxTransform;</td> </tr> <tr class="row9"> <td class="col0" colspan="2">q</td><td class="col2" colspan="2"> a quaternion</td><td class="col4" colspan="2"> cQuaternion qRotation;</td> </tr> <tr class="row10"> <td class="col0" colspan="2">a</td><td class="col2" colspan="2"> an argument</td><td class="col4" colspan="2"> void Func(int alX) { </td> </tr> <tr class="row11"> <td class="col0" colspan="2">m</td><td class="col2" colspan="2"> a member variable </td><td class="col4" colspan="2"> class cMyClass {<br/> int mlMember;<br/> } </td> </tr> <tr class="row12"> <td class="col0" colspan="2">g</td><td class="col2" colspan="2"> a global variable, defined outside of a class or function.</td><td class="col4" colspan="2"> int glMyGlobal; <br/> class cMyClass {} </td> </tr> </table> <span class='np_break'> </span> </div> <p> a variable name always starts with a lower case letter, so anything of type not specified must start with a lower case word. Example: </p> <pre class="code c++">cMyOwnClass myClass<span class="sy0">;</span> </pre><p> </p> <p> If combining two prefixes, and one consist of more than one letter, then have an underscore between them. Example: </p> <pre class="code c++">cMatrix m_mtxMemberMatrix<span class="sy0">;</span> </pre><p> </p> </div> <h3>Comments</h3> <div class="level3"> <p> Always comment the code you write; when scripting, it is always certain somebody else will work on it. Comment to make other people understand what it means and to make the code look nicer. </p> <p> <b>Function/Class comment</b> <br/> Use comment blocks for the main comment for each class/function, this so that the parser can show the correct info for code compleition/hints. Only for helpers and similar type of base functions where the information is needed. </p> <pre class="code c++"><span class="coMULTI">/** * Change the light radius to the specified value. * * @param tString asLight, name of the light to change radius of. * @param float afRadius, the radius in meters to set for the light. **/</span> <span class="kw4">void</span> LightChangeRadius<span class="br0">(</span><span class="kw4">const</span> tString <span class="sy0">&</span>in asLight<span class="sy0">,</span> <span class="kw4">float</span> afRadius<span class="br0">)</span> <span class="br0">{</span>   <span class="br0">}</span> </pre><p> </p> <p> <b>Section comment</b> <br/> When starting a new section of some kind do a comment that explains what is going on. </p> <pre class="code c++"><span class="co1">////////////////////////////////////////////</span> <span class="co1">// Update the monster damage</span> cMonster@ pMonster <span class="sy0">=</span> CurrentHit<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="kw4">float</span> fDamage <span class="sy0">=</span> RandomDamage<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> fDamage <span class="sy0">-=</span> pMonster<span class="sy0">-></span>Defense<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="kw1">if</span><span class="br0">(</span>fDamage< 0<span class="br0">)</span> fDamage <span class="sy0">=</span><span class="nu0">0</span><span class="sy0">;</span> fDamage <span class="sy0">*=</span> mfHitMultiplier<span class="sy0">;</span> pMonster<span class="sy0">-></span>DecHealth<span class="br0">(</span>fDamage<span class="br0">)</span><span class="sy0">;</span> </pre><p> </p> <p> <b>Single line comment</b> <br/> When commenting a single line </p> <pre class="code c++"><span class="co1">//The square of the distance will be enough</span> <span class="kw4">float</span> fDistSqr <span class="sy0">=</span> vDiff.<span class="me1">x</span><span class="sy0">*</span>vDiff.<span class="me1">x</span> <span class="sy0">+</span>vDiff.<span class="me1">y</span><span class="sy0">*</span>vDiff.<span class="me1">y</span><span class="sy0">;</span> </pre><p> </p> <p> Only do this in rare cases when it is really hard to figure what the code means. Normally, simply using section comments is enough. If you split the code into nice sections and name them well, that should be more than enough for other people to figure out what it is about. </p> <p> <b>Function/Class separation</b> <br/> Use this to make it easier to see functions and classes. Can also be used to encapsulate other data. </p> <pre class="code c++"><span class="kw4">void</span> Foo<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>   <span class="br0">}</span>   <span class="co1">//-------------------------------------------</span>   <span class="kw4">void</span> Bar<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>   <span class="br0">}</span> </pre><p> </p> </div> <h2>Containers</h2> <div class="level2"> <p> There are some containers that are not part of the angelscript language, but added as extension, these will be described here. </p> </div> <h3>Array</h3> <div class="level3"> <p> Arrays are simple linear storage containers. </p> <p> You can access elements using <em>varname[index]</em>. </p> <p> <b>Syntax:</b><br/> </p> <pre class="code c++">array< T<span class="sy0">></span> or T<span class="br0">[</span><span class="br0">]</span> </pre><p> </p> <p> <b>Methods</b><br/> </p> <pre class="code c"><span class="kw4">void</span> insertAt<span class="br0">(</span>uint<span class="sy0">,</span> <span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">void</span> removeAt<span class="br0">(</span>uint<span class="br0">)</span> <span class="kw4">void</span> insertLast<span class="br0">(</span><span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">void</span> insertBack<span class="br0">(</span><span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">void</span> removeFirst<span class="br0">(</span><span class="br0">)</span> <span class="kw4">void</span> removeLast<span class="br0">(</span><span class="br0">)</span> uint length<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="kw4">void</span> resize<span class="br0">(</span>uint<span class="br0">)</span>   <span class="kw4">void</span> sortAsc<span class="br0">(</span><span class="br0">)</span> <span class="kw4">void</span> sortAsc<span class="br0">(</span>uint<span class="sy0">,</span> uint<span class="br0">)</span> <span class="kw4">void</span> sortDesc<span class="br0">(</span><span class="br0">)</span> <span class="kw4">void</span> sortDesc<span class="br0">(</span>uint<span class="sy0">,</span> uint<span class="br0">)</span> <span class="kw4">void</span> reverse<span class="br0">(</span><span class="br0">)</span> <span class="kw4">int</span> find<span class="br0">(</span><span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">const</span> <span class="kw4">int</span> find<span class="br0">(</span>uint<span class="sy0">,</span> <span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">const</span>   <span class="kw4">void</span> push_back<span class="br0">(</span><span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">void</span> push_front<span class="br0">(</span><span class="kw4">const</span> T<span class="sy0">&</span>in<span class="br0">)</span> <span class="kw4">void</span> pop_back<span class="br0">(</span><span class="br0">)</span> <span class="kw4">void</span> pop_front<span class="br0">(</span><span class="br0">)</span> uint size<span class="br0">(</span><span class="br0">)</span> const </pre><p> </p> </div> <h2>Included files</h2> <div class="level2"> <p> File can be included using the <em>#include</em> key word. This will look in all folders that have been declared in resources.cfg. </p> <p> An important thing to think about is that any enums, classes, interfaces, etc that are meant to be shared, needs to be declared with the <em>shared</em> keyword. Example: </p> <pre class="code c++"> shared <span class="kw2">enum</span> eMyEnum <span class="br0">{</span> shard interface iMyInterface <span class="br0">{</span> </pre><p> </p> <p> <span class='np_break'> </span> If this is not done, then the data types will be declared as different types in all files that include the files, which will lead to exceptions, or worse crashes. </p> </div> <h2>User Classes</h2> <div class="level2"> <p> Script user classes are C++ classes that implement the iScriptUpdateableUserClassInterface interface. </p> <p> The script for these classes must contain the code:<br/> </p> <pre class="code c">cUserClass@ mBaseObj<span class="sy0">;</span> <span class="kw4">void</span> SetupBaseInterface<span class="br0">(</span>cUserClass@ aObj<span class="br0">)</span><span class="br0">{</span>@mBaseObj <span class="sy0">=</span> aObj<span class="sy0">;</span><span class="br0">}</span> </pre><p> </p> <p> <span class='np_break'> </span> Where "cUserClass" is the name of the implemented user class. </p> <p> These classes can choose to implement the method: </p> <pre class="code c"><span class="kw4">void</span> Init<span class="br0">(</span><span class="br0">)</span> </pre><p> </p> <p> <span class='np_break'> </span> This method is called upon creation of the class object, but <u>not</u> on reload. </p> <p> The constructor of the class is called on creation <u>and</u> on reload. However, note that the handle <em>mBaseObj</em> is not initialized when the constructor is called and hence may only be used in <em>Init()</em>. </p> </div> <h2>Script Classes</h2> <div class="level2"> <p> Script classes are whatever class that is created in script. </p> </div> <h3>Handles</h3> <div class="level3"> <p> For any script that is to be saved (which means all scripts pretty much), handles to script classes can NOT be member variables. So a script file like: </p> <pre class="code c++">class cMyClass <span class="br0">{</span> ... <span class="br0">}</span> class cMyOtherClass<span class="br0">{</span> ... <span class="me1">cMyClass</span>@ mpMyClass<span class="sy0">;</span> <span class="br0">}</span> </pre><p> </p> <p> is NOT supported. The reason for this is that when a script is destroyed any handle to these classes are destroyed too and cannot be retrieved again! </p> <p> It is however okay to to pass handles as arguments: </p> <pre class="code c++"><span class="kw4">void</span> MyFunc<span class="br0">(</span>cMyClass@ apArg<span class="br0">)</span> <span class="br0">{</span> ... <span class="br0">}</span> </pre><p> </p> <p> or use them as local or global variables. </p> <pre class="code c++">cMyClass@ gpGlobalVar <span class="kw4">void</span> MyFunc<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> </pre><p> </p> <pre class="code c++"><span class="kw4">void</span> MyFunc<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> cMyClass@ pLocalVar ... <span class="br0">}</span> </pre><p> </p> <p> Its only when they are to be saved that problems arise. </p> </div> <h3>ID Handles</h3> <div class="level3"> <p> When working with engine types it is recommended to use ID handles instead of class pointers. </p> <pre class="code c++">class cMyClass <span class="br0">{</span> iPhyiscsBody@ mpBody <span class="br0">}</span> </pre><p> </p> <p> Using class handler directly like this works but it is unsafe and does not support saving. Instead the handle can be saved like this. </p> <pre class="code">class cMyClass { tID mBody; } </pre><p> </p> <p> This saves a unqiue identifier to the body. The ID of a object can be retrived by calling GetID() function. There are script functions for converting the ID to a class handle. </p> <pre class="code">void MyFunc() { iPhysicsBody@ pBody = cLux_ID_PhysicsBody(mBody); if(pBody !is null) { ... } } </pre><p> </p> <p> This retrives the class handle from the engine so that it can be used. Retriving the class handle from the ID is very fast. </p> <p> Using a ID instead of a class handle has two big advantages. Unlike class handles the ID can be saved. When loading the save file the ID will still work and retrive the same object. </p> <p> If the object that the ID handle points to gets deleted anywhere else in the code the ID will still be safe. When trying to retrive a deleted object the function will return null. Accessing null pointers will never cause the game to crash. When accessing a class handle that has been deleted that leads to accessing deallocated memory and the game will crash. </p> </div> <h2>Script Callbacks</h2> <div class="level2"> </div> <h3>Calling script functions from scripts</h3> <div class="level3"> <p> If you want to run a script function/method from script using the Prepare, Execute, SetArg, etc you need to make sure that string arguments are NOT refences from C++ code. For example this is NOT allowed: </p> <pre class="code c++"><span class="kw1">if</span><span class="br0">(</span>mObj.<span class="me1">ScriptPrepare</span><span class="br0">(</span>"void DoSomething<span class="br0">(</span>string <span class="sy0">&</span>in asStr<span class="br0">)</span>"<span class="br0">)</span> <span class="br0">)</span><span class="br0">{</span> SetArgString<span class="br0">(</span><span class="nu0">0</span><span class="sy0">,</span> mObj.<span class="me1">GetName</span><span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span><span class="sy0">;</span> ScriptExecture<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="br0">}</span> </pre><p> </p> <p> Where mObj is of class cMyObj implemented in C++: </p> <pre class="code c++">cMyObj <span class="br0">{</span> ... <span class="me1">tString</span><span class="sy0">&</span> GetName<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> <span class="br0">}</span> </pre><p> </p> <p> What is wrong here is that the argument is "string &in", an in reference. The reason why this is bad is because when the string sent to the callback function is a reference and the string returned from C++ is also this. What happens when a reference is returned from script is that the Script makes a copy of the class and then provides a reference to this. In the example above, the variable returned from GetName() only has a scope lasting the function call. So when we arrive at ScriptExecute, the reference is gone. </p> <p> To fix this you can do one of two things. One is to make sure that the argument for the called function is not a reference, like: </p> <pre class="code">if(mObj.ScriptPrepare("void DoSomething(string in asStr)") ){ </pre><p> </p> <p> Or you can simply save the variable as a script one and then set that one, like: </p> <pre class="code c++">tString sName <span class="sy0">=</span> mObj.<span class="me1">GetName</span><span class="br0">(</span><span class="br0">)</span> SetArgString<span class="br0">(</span><span class="nu0">0</span><span class="sy0">,</span> sName <span class="br0">)</span><span class="sy0">;</span> ScriptExecture<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span> </pre><p> </p> <p> In the last example, the variable (sName) is in scope until after ScriptExecute is called, and hence for the as long as needed. </p> </div> <h2>Global Functions</h2> <div class="level2"> <p> Global functions make it easier to communicate between separate script modules. They are the slowest form of function calling but can also be very nice to use, just do not use it in performance sensitive functions (eg functions that get called many times in an update loop). </p> <p> <b>1)</b> Before running the Global function, all the arguments need to be set up. Example: </p> <pre class="code c++">cScript_SetGlobalArgBool<span class="br0">(</span><span class="nu0">0</span><span class="sy0">,</span> <span class="kw2">true</span><span class="br0">)</span><span class="sy0">;</span> cScript_SetGlobalArgVector3f<span class="br0">(</span><span class="nu0">1</span><span class="sy0">,</span> cVector3f<span class="br0">(</span><span class="nu0">1</span><span class="sy0">,</span><span class="nu0">2</span><span class="sy0">,</span><span class="nu0">3</span><span class="br0">)</span><span class="br0">)</span><span class="sy0">;</span> cScript_RunGlobalFunc<span class="br0">(</span>"MyClassObj"<span class="sy0">,</span> "cMyClass"<span class="sy0">,</span> "MyGlobalFunc"<span class="br0">)</span><span class="sy0">;</span> </pre><p> </p> <p> <b>2)</b> The return value must be gotten before any other global function is called, else it goes away.<br/> This is okay: </p> <pre class="code c++">... <span class="me1">cScript_RunGlobalFunc</span><span class="br0">(</span>"MyClassObj"<span class="sy0">,</span> "cMyClass"<span class="sy0">,</span> "MyGlobalFunc"<span class="br0">)</span><span class="sy0">;</span> bool bReturnFromMyGlobalFunc <span class="sy0">=</span> cScript_GetGlobalReturnBool<span class="br0">(</span><span class="br0">)</span> cScript_RunGlobalFunc<span class="br0">(</span>"MyClassObj"<span class="sy0">,</span> "cMyClass"<span class="sy0">,</span> "SomeOtherFunc"<span class="br0">)</span><span class="sy0">;</span> </pre><p> </p> <p> <span class='np_break'> </span> This is NOT okay: </p> <pre class="code c++">cScript_RunGlobalFunc<span class="br0">(</span>"MyClassObj"<span class="sy0">,</span> "cMyClass"<span class="sy0">,</span> "MyGlobalFunc"<span class="br0">)</span><span class="sy0">;</span> cScript_RunGlobalFunc<span class="br0">(</span>"MyClassObj"<span class="sy0">,</span> "cMyClass"<span class="sy0">,</span> "SomeOtherFunc"<span class="br0">)</span><span class="sy0">;</span> bool bReturnFromMyGlobalFunc <span class="sy0">=</span> cScript_GetGlobalReturnBool<span class="br0">(</span><span class="br0">)</span> </pre><p> </p> <p> (it would be getting the return value from <em>SomeOtherFunc</em>.) </p> <p> <b>3)</b> When creating a function that is to be global, it must have void as return value and no arguments. Example: </p> <pre class="code c++"><span class="kw4">void</span> MyGlobalFunc<span class="br0">(</span><span class="br0">)</span> </pre><p> </p> <p> <b>4)</b> The implemented global function must get all arguments using </p> <pre class="code">void MyGlobalFunc() { bool bArg0 = cScript_GetGlobalArgBool(0); cVector3f vArg1 = cScript_GetGlobalArgVector3f(1); </pre><p> </p> <p> <b>5)</b> When calling a global function, it is okay to have one or more asterix in the object name and then several object will be called. For example <em>"My*test"</em> would call: <em>"MyNiceTest"</em> and <em>"MyBadTest"</em>. However, this will be a bit slower, so be careful when using it (eg not during things called every update) </p> </div> <h2>Saving</h2> <div class="level2"> <p> To skip saving a variable, you must use metadata keyword [nosave] in front of the the variable name. Examples: </p> <pre class="code c++"><span class="br0">[</span>nosave<span class="br0">]</span> <span class="kw4">float</span> mfT<span class="sy0">;</span> <span class="br0">[</span>nosave<span class="br0">]</span> cMyClass@ mHandle<span class="sy0">;</span> </pre><p> </p> <p> If you only want to save the actual pointer for a handle, but not any data, then use the prefix [nodatasave] Example: </p> <pre class="code c++"><span class="br0">[</span>nodatasave<span class="br0">]</span> cMyClass@ mNoSaveHandle<span class="sy0">;</span> </pre><p> </p> <p> Also, there is a the prefix [volatile], this will do the same as a [nosave] but will also make sure that variable is not even saved during script reload. This should be used on handles where you are never sure if saved variable can invalid, for instance cSoundEntity and cParticleSystem (that can be deleted by the engine). </p> <pre class="code c++"><span class="br0">[</span><span class="kw4">volatile</span><span class="br0">]</span> cSoundEnity@ mpCurrentSoundEntity<span class="sy0">;</span> </pre><p> </p> <p> Instead of using class handler here it is better to store the ID to the object. The ID can be saved and will work correctly on load. </p> <pre class="code">tID mCurrentSoundEntity; </pre><p> </p> <p> In case you have an array of handles where none of the properties should be saved, this is NOT possible. Instead save names of IDs of the objects in the array. </p> </div> <h2>Optimizing</h2> <div class="level2"> <p> All of the optimizations tips are meant to be used when speed is of essence. It is good to always use them when possible, but it is even more important to have the code readable, so take that into account too! </p> <p> <b>Declare Local Variables Outside Loops</b><br/> Try and keep the local variables outside a loop. So instead of doing: </p> <pre class="code c++"><span class="kw1">for</span><span class="br0">(</span><span class="kw4">int</span> i<span class="sy0">=</span><span class="nu0">0</span><span class="sy0">;</span> i< 1000<span class="sy0">;</span> <span class="sy0">++</span>i<span class="br0">)</span> <span class="br0">{</span> <span class="kw4">float</span> fX <span class="sy0">=</span> GetSomeThing<span class="br0">(</span>i<span class="br0">)</span><span class="sy0">;</span> ... <span class="br0">}</span> </pre><p> </p> <p> <span class='np_break'> </span> Do it like this instead: </p> <pre class="code c++"><span class="kw4">float</span> fX<span class="sy0">;</span> <span class="kw1">for</span><span class="br0">(</span><span class="kw4">int</span> i<span class="sy0">=</span><span class="nu0">0</span><span class="sy0">;</span> i< 1000<span class="sy0">;</span> <span class="sy0">++</span>i<span class="br0">)</span> <span class="br0">{</span> fX <span class="sy0">=</span> GetSomeThing<span class="br0">(</span>i<span class="br0">)</span><span class="sy0">;</span> ... <span class="br0">}</span> </pre><p> </p> <p> <span class='np_break'> </span> That way they script does not need to create the local var for every loop and this can boost performance quite a bit! </p> <p> <b>Include only what is needed</b><br/> Make sure that you only include hps files that are really needed. Having includes that are not used can eat up a lot of extra loading time very easily! </p> </div> <h2>Important notes</h2> <div class="level2"> <p> C++ scriptable classes with classes in can not be abstract ones. It must always be the top class in the hierarchy that is used and saved. </p> </div>