diff options
| -rw-r--r-- | design.tex | 84 | ||||
| -rw-r--r-- | img/class-scripts.puml | 48 | ||||
| -rw-r--r-- | reqs.toml | 33 |
3 files changed, 165 insertions, 0 deletions
@@ -36,6 +36,90 @@ workflows. \subsection{Scripting} +The scripting interface was designed around a `target' \gls{api} (described by +\cref{req:script:interface,req:script:user-class,req:script:direct-instance,req:script:direct-run}). +An example of this \gls{api} is shown below:\noparbreak + +\begin{blockcode} +class MyScript : public BehaviorScript { + void update() { + // update code here + } + // init() also exists, but is empty by default +}; + +{ // in scene initialization + GameObject & obj = ...; + obj.add_component<MyScript>(); +} +\end{blockcode} + +The above call to \codeinline{GameObject::add_component} cannot work correctly +without significantly increasing the complexity of the component manager, so the +following restrictions were taken into account when creating the script system +architecture:\noparbreak + +\begin{itemize} + \item The first template parameter passed to \codeinline{GameObject::add_component} + \emph{must} be a base `script \emph{component}' class, so each derived user + script class is instantiated in the same generic script list. + \item C++ does not allow passing types (i.e.~\codeinline{MyScript} in this case) as + function parameters, so a function call like + \codeinline{add_component<BehaviorScript>(MyScript)} cannot be realized. +\end{itemize} + +\subsubsection{Architecture} + +The restrictions detailed at the start of this section are mitigated as +follows:\noparbreak + +\begin{itemize} + \item User scripts are split into two classes--- + \begin{enumerate} + \item a script \emph{interface} class (\codeinline{Script}) + \item a script \emph{component} class (\codeinline{BehaviorScript}) + \end{enumerate} + \item \codeinline{GameObject::add_component} receives the script \emph{component} + as template parameter + \item \codeinline{GameObject::add_component} now always returns a reference to the + component instance + \item The script component class has a setter function that takes a template + parameter for classes derived from the base script \emph{interface} class +\end{itemize} + +\Cref{fig:class-scripts} shows the resulting structure as a class diagram. It +contains the following classes:\noparbreak +\begin{description} + \item[Script] This is the script \emph{interface}, and is used by the game + programmer to create derived script classes. All methods in this class are + declared virtual and have an empty implementation. + + This class' methods are protected by default, and a friend relation to + \codeinline{ScriptSystem} is used to ensure only \codeinline{ScriptSystem} is + able to call these methods. + + Only classes derived from \codeinline{Script} can be used with + \codeinline{BehaviorScript::set_script}'s template parameter \codeinline{T}. This + function returns a reference to the \codeinline{BehaviorScript} instance it was + called on so it can be chained after the call to + \codeinline{GameObject::add_component}. + \item[BehaviorScript] + This is the script \emph{component}, and is given as the template parameter to + \codeinline{GameObject::add_component}. + + This class also uses a friend relation to \codeinline{ScriptSystem} to restrict + access to its private reference member \codeinline{script}. + \item[ScriptSystem] This is the system class that runs the methods implemented in + the derivative instances of \codeinline{Script}. +\end{description} + +\begin{figure} + \centering + \includepumldiag{img/class-scripts.puml} + \caption{User script class diagram} + \label{fig:class-scripts} +\end{figure} + \subsection{Audio} \subsubsection{Library} diff --git a/img/class-scripts.puml b/img/class-scripts.puml new file mode 100644 index 0000000..8fc36c9 --- /dev/null +++ b/img/class-scripts.puml @@ -0,0 +1,48 @@ +@startuml +!include theme.ipuml +skinparam Linetype ortho +skinparam Nodesep 75 +skinparam Ranksep 30 + +class ComponentManager <<irrelevant>> + +package api { + class Component <<irrelevant>> + + class Script { + # init() <<virtual>> + # update() <<virtual>> + -- + - Script() + } + + class BehaviorScript { + # BehaviorScript() + + ~BehaviorScript() + -- + + set_script<T>() : this & + -- + # script : Script * + } + + BehaviorScript -u-|> Component + Script .u.> BehaviorScript +} + +class System <<irrelevant>> +class ScriptSystem <<Singleton>> { + + get_instance() : ScriptSystem & <<static>> + + update() + -- + - ScriptSystem() + - ~ScriptSystem() +} + +System <|-- ScriptSystem +ScriptSystem .[norank]> ComponentManager + +ScriptSystem .[norank]> api.Script : < friend +ScriptSystem .[norank]> api.BehaviorScript : < friend +ComponentManager .[norank]> api.BehaviorScript : < friend + +@enduml @@ -84,3 +84,36 @@ Windows. # TODO: library documentation as quality factor? # TODO: modularity over less libraries? (i.e. why don't we just SDL2 everything?) +[script:interface] +type = 'system' +priority = 'must' +description = ''' +There is a base \codeinline{Script} class that has empty default +implementations for functions that may be implemented by the game programmer. +''' + +[script:user-class] +type = 'system' +priority = 'must' +description = ''' +The game programmer implements scripts by creating classes derived from the +\codeinline{Script} class. +''' + +[script:direct-instance] +type = 'system' +priority = 'must' +description = ''' +Unless explicitly changed by the game programmer, derived script classes cannot +be instantiated directly, and must be instantiated by the component manager. +''' + +[script:direct-run] +type = 'system' +priority = 'must' +description = ''' +Unless explicitly changed by the game programmer, methods on instances of +\codeinline{Script} (and derivative) classes cannot be called directly, and +must be called by the script system. +''' + |