diff options
Diffstat (limited to 'design.tex')
| -rw-r--r-- | design.tex | 91 |
1 files changed, 88 insertions, 3 deletions
@@ -24,9 +24,94 @@ workflows. \section{Overview} -% TODO: high-level design introduction -% - which parts of the design are prerequisites (and therefore not designed by us) -% - why are all parts in the following section arranged in the way they are +As described above, the cr\^epe game engine's goal is to offer a Unity-like +experience tailored for developing 2D games similar to Jetpack Joyride. That is why +Jetpack Joyride and Unity provided the main inputs for this game engine design. +Firstly, a quick overview will be given of the Unity game engine, in particular the +\gls{ecs}. Secondly, this Overview will quickly talk you through some of the most +important parts of the game engine, and why these parts are needed to create the +Jetpack Joyride game. + +\subsection{ECS} + +The Unity game engine is structured using the Entity Component System (\gls{ecs}) (as +shown in \cref{fig:ecs-block-diagram}). The \gls{ecs} is made out of three main +subsystems, namely entities, components and systems. Entities are just IDs. An entity +is also called a GameObject in Unity and it is made out of one (or more) components. +Components are the classes that hold the data. The components determine what kind of +entity it is (e.g. an enemy, audio, and so on). Systems take care of the behavior of +the entities. Systems mainly read and write the enity's components data. The +\gls{ecs} clearly distinguishes the data (components) from the functionality +(systems). + +\begin{figure} + \centering + \includegraphics[width=0.5\textwidth]{img/ECSBlockDiagram.png} + \caption{ECS design pattern} + Source: \autocite{img:ecs-block-diag} + \label{fig:ecs-block-diagram} +\end{figure} + +The \gls{ecs} will also be used at the cr\^epe game engine. Everything (from the +protagonist and bullets to the walls and enemies) in the cr\^epe game engine will be +a GameObject (i.e.~entity). The game programmer must program his game by creating all +kind of GameObjects and placing them in one (or multiple) scenes, just like Unity. + +\subsection{Jetpack Joyride} + +Firstly, some background information about Jetpack Joyride. Jetpack Joyride is a +side-scrolling endless runner action video game created by Halfbrick Studios. The +protagonist is called Barry Steakfries, who the player controls as he steals a +bullet-powered jet pack from a top-secret laboratory +\autocite{wikipedia:jetpack-joyride}. A screenshot from the game can be seen in +\cref{fig:jetpack-joyride} (pleae be aware that the goal of this project is not to +create an exact replica of Jetpack Joyride, it is only used as a source of +inspiration). + +\begin{figure} + \centering + \includegraphics[width=0.5\textwidth]{img/JetpackJoyride.jpg} + \caption{Jetpack Joyride} + Source: \autocite{img:jetpack-joyride} + \label{fig:jetpack-joyride} +\end{figure} + +The protagonist wears a jetpack with which he can float in the air. The player must +avoid obstacles (such as lasers, missiles and zappers) by floating at the right +height. The player can control the protagonist's jetpack, thereby also controlling +the protagonist's height. The protagonist experiences gravity and other forces (like +the force from his jetpack pushing him upwards). These forces should be easily +programmable by the game programmer. That is why a physics system is needed in the +cr\^epe game engine. Only very limited/easy physics are needed for Jetpack Joyride, +that is why this is only supported by the cr\^epe game engine. + +The protagonist must avoid obstacles. That is why the cr\^epe game engine should also +support a collision system. Again, only very limited/easy collision is needed for +Jetpack Joyride, that is why only very limited/easy collision is supported by the +cr\^epe game engine. + +The game must, of course, also be visible to and playable by the user. A rendering +system will take care of rendering (displaying) the game and its GameObjects. An +input system will take care of all the inputs (mouse and keyboard). + +Jetpack Joyride also offers audio. A system will take care of the audio in the +cr\^epe game engine. + +Particles are very common in Jetpack Joyride, e.g. underneath the jetpack and behind +the rockets. Particles will be supported by the particle system. + +The start of a scene is described in a scene. However, the game programmer might also +want to write game logic code which is running during the game (e.g. to switch to a +new scene or to perform a custom action at a collision). For these purposes, Unity +uses scripts. These scripts will also be supported by the cr\^epe game engine. + +Finally, as an extra, replay functionality will be supported by the cr\^epe game +engine. A dedicated replay system will be used to support replay. + +It turns out that a physics, collision, rendering, input, audio, particle, script, +and replay system are needed to create the Jetpack Joyride game. These systems form +the main part of the \gls{ecs}. The design of these eight systems in combination with +\gls{ecs}, will be briefly discussed in the next parts of this design document. \section{Design} |