..... l ss t h t an an $100,000 of 000 of ann an u n al u al gross r evenu n e

Transcription

1 Outline Introduction to Game Programming Autumn Game architecture case Unity game engine Juha Vihavainen University of Helsinki Basic concepts and architecture of Unity On origins/developments of Unity Unity as an integrated development environment (IDE): Unity world/level editor and its major user interfaces The logical architecture of a Unity game scenes => game objects => components => settings, scripts Asset handling in Unity; ; project's reusable models and images (textures)) are seen in Project pane (located in Assets folder) Briefly on implementation and architecture of the Unity engine Unity scripting in more detail later 2 References Lots and lots of Unity documentation and manuals, both online and printed versions Michael P. Rogers, Bringing Unity to the classroom. In Journal of Computing Sciences in Colleges 27 (2012), 5 (May), Philip Chu, Game development with Unity,, Technicat LLC, (One nice condensed introduction to Unity) Joseph Hocking, Unity in Action - Multiplatform game development in C# with Unity 5. Manning, Choosing a game engine One option was an in-house game engine that usually only did what the game required Then, commercial full-featuredfeatured Unreal (by Epic Games,, USA) and CryEngine (by German game developer Crytek) ) were often licensed on a per-game basis The Unity engine and development environment has become a popular choice as an engine for small studios and individuals offers a lot of high-end features (physics, integrated asset mgmt..) has a free version and low-cost Pro versions (details changing) runs either on a Mac (originally) or on a Windows PC targets several platforms; in 2013, made the ios and Android licenses free for Unity free-version users Unity Free has no fee; it is available for any use to individuals or companies with less than $100,000 of annual gross revenue 4

2 Background: many kinds of libraries/engines Game development is mostly in C/C++ and script languages, e.g. Unreal Engine uses C++ (for core system code) and optionally a custom visual script language Blueprint (for gameplay) Unity is mostly implemented in C++ (and partly in Boo,, I think) but can use UnityScript and C# as scripting languages Blender is coded in C, C++ and Python; Python is used as an internal scripting language (including its game engine part) Ogre graphics engine (over 1,300,000 lines of C++) OpenGL and DirectX graphics libraries (low level, in C) Use mostly the same fundamental concepts (graphics, update loop) We ll do little or no 3D modeling; it is assumed friendly artists will do that for us (or we can search free assets from the web) We ll only be interested in interactive video games, and not in general graphics Unity basics Unity is a multi-platform development tool platforms include: desktops, mobile devices, web pages, consoles Unity s visual editor has several sections that work together build/edit scenes/levels, editing of a selected game object (in inspector pane) scripts are attached to objects as special kinds of components,, and executed by a hidden game loop a Unity project is represented by a folder C# scripts are edited and processed by a separate programming environment (MonoDevelop/Visual Studio); UnityScript by a suitable text editor interactions/processing between different sections (views) is mostly automatic, e.g., updating settings change visuals 5 6 On history/developments (2005 -> ) Started 2005 as a Mac-based tool developing for Mac and Windows Windows-based version available 2009 (Unity 2.5) Unity 3.5 (Feb 2012), new Shuriken particle system, HDR, etc. Unity 4 (June 2012): Mecanim animation system (bought), DirectX11 support, Ubuntu platform, etc. Unity 4.2 (July 2013): Android, ios, Windows Phone 8, etc. were included with the free license; dyn. shadows w/ one-directional light Unity 4.3 (2013) added complete native 2D tools (instead of 3rd-party 2D tools), blendshape facial animation, among others In July 2013, reached over 2 million registered Unity users (downloads) In March 3, 2015, the release of Unity 5.0 had improvements in shading techniques, lighting, audio, animation, WebGL (soon), etc. 7 Some more history On May 21, 2002, Nicholas Francis, a Danish programmer, posted on the Mac OpenGL board asking for assistance with a shader system he was trying to implement into his game engine; Joachim Ante responded; David Helgason heard about the project and thought they were "really onto something", so jumped aboard as the third developer Unity: "A A toolset used to build games, and.. the technology that executes the graphics, the audio, the physics, the interactions, and the networking" Nowadays, Unity has hundreds of employees around the world Needed to make a full commercial game using their new engine; Gooball was published in March 2005 Using the profits from Gooball,, the company hired more developers to refine Unity before its initial 1.0 release in June 2005 an opportunity to tear apart the engine to find bugs, remove annoyances, and fix the interface before its official release 8

3 Some distinguishing features Supports development of a wide range of games on diverse platforms Supports C# # and UnityScript (earlier also Boo) ) as scripting languages A single IDE provides prototyping tools for game development edit world/level => edit components/scripts => run the game =>.. Applies Composite, Component, Prototype, Game Loop, Update Method plus other design patterns in its design and implementation Inheritance vs. components Unity in Action - Multiplatform game development in C# by Joseph Hocking. Especially, uses a well-thought design for game objects uses a version of "property property-centric centric" " approach to game objects dynamic components simulate multiple inheritance/mixins (to compose an object from multiple varying parts) Utilizes C# built-in in iterators to implement a coroutine facility => one script (code block with state) may span multiple frames 9 10 Unity game engine: basic concepts An asset is anything that is imported into your project (project view), and then to be instantiated & placed into the game world (scene view) Scenes are used to create different levels (a term used by Unity docs) separately loaded / managed (game object space and assets) to make a "persistent"" object: call DontDestroyOnLoad (object) A game object is a essentially a container for components A component is something to be attached to a game entity, describing some property, capability, behaviour, or relationship created independently but always attached to some game object can be separately removed and destroyed A script is a special kind of component that defines the behaviour of a game object; the same script class can be "attached" to multiple gameobjects, and multiple scripts can be attached to the same object 11 How to start a game development with Unity 1. Create a Unity project for the game (creates a folder, actually) 2. Import assets via menu,, or (directly) to the Assets folder 3. Create a scene for each level (or a game screen/page) 4. In each scene, select and place initial assets into the game world 5. Adjust/place the main (default) camera; ; add cameras as desired 6. Add light objects, adjust ambient light.. 7. Add and adjust materials in objects' renderer components 8. Attach rigidbodies, physics materials, colliders to objects 9. Write and attach scripts to objects. 10. Test the game in the Editor's "Game Window" " (pane, view) 11. Publish to the desired platform, building selected scenes 12

4 Parts of the interface in Unity The main parts of the UI of Unity Editor 1. Project view shows all of the project's assets, possibly in their own subfolders (can select one one-- or two two--column formats) 2. Scene view where we arrange and manipulate game objects; describes the initial configuration (state) of the level (scene) 3. Hierarchy view lists the objects of the current scene in a tree form (an alternative view on all the game objects, in alphabetical order) 4. Game window shows the running game (as seen by the player) 5. Inspector where we can access asset parameters, game objects' settings, components, script fields, and scene or project settings 6. Console can display system errors and warnings, user log/trace output with Debug.Log ("Hello");, ("Hello");, etc. Note. Never rearrange or rename the contents of the project s assets Note. folder outside the Unity editor (but just adding/updating is OK) Editor screenshot: Toolbar Toolbar,, Scene Scene,, and Game 16

5 Sample of Unity Editor toolbar controls Game world/level Hierarchy Project pan move rotate scale orbit Manipulate the selected game object Inspector To selectively control which objects are rendered by which cameras or lit by which lights (also collisions and raycasting) 17 object Unity game architecture Alt + RHB Game "player" (~ video player) Running game zoom Alt Select from default or predefined world Editor layouts 18 The main entities in Unity by [Petri Veijonen] Unity's own root class C# root class - combines aggregation with inheritance The game objects (included in a scene) form a treetree-like hierarchy determined by parentparent-child relationships ( ~ scene graph) graph) children are affected by changing the parent's transform properties: position position,, rotation rotation,, and scale a child can also be changed and updated independently, but the transform properties are interpreted in relation to the parent AddComponent (type) GetComponent (type) : Component Object.Destroy (obj) Can be enabled/disabled Game object scripts Transform is not optional childcount parent GetChild (index):transform; Hierarchy view: the initial contents of the scene Light AudioListener AudioSource 19 materials (shaders) 20

6 Get common Components via public variables. Note the duplication of interfaces in GameObject and Component... // these are obsolete... +name is inherited Note. Not identical. BroadcastMessage calls the method on MonoBehaviours in this game object or any of its children (a tree). Attach responsibilities to an object dynamically. Provides an alternative to subclassing. // these four has been deprecated in 5.0.; use GetComponent GameObject is sealed, Component is not. 21 Common game object components Transform specifies position, rotation, and scale MonoBehaviour adds custom functionality (as scripts) MeshFilter represents a 3D mesh from the Assets folder MeshRenderer draws the game object (with settings/materials..) Collider makes rigid bodies react when colliding/touching Rigidbody makes a game object obey physics (gravity, drag..) but kinematic rigidbodies if moved only by its Transform but they still affect other physics-controlled controlled objects Camera to view the world from the game object's perspective Light can act as a lighting source (lamp, other emissive object) CharacterController moves an object by a script, instead of a Rigidbody (still affected by collisions) GUIText to be associated with a particular game object 22 The class MonoBehaviour A script's public variables are viewed and edited within the IDE: booleans appear as checkboxes; strings as textfields; etc. Initialization in the Inspector overrides initialization in the script code 23 The base class for scripts Awake (), Start (), Update (), FixedUpdate (), LateUpdate (), and OnGUI () are kind of callbacks (executed by the engine) The variable gameobject refers to the owner game object; also: transform, name, tag Convenient notation to access other components (null if not attached): c = GetComponent <Collider> ();... c = script.getcomponent <Camera> (); Sample of services; some events require colliders can be enabled/ disabled Delayed calls Coroutines named by string value Callbacks called if present 24

7 Colliders in Unity Colliders give game objects a "physical presence" " so that they "interact"" (touch, push, collide) with each other A mesh collider follows the surface of a geometry (model): expensive Each primitive (built-in) in) game object has a default collider; they are more efficient Set physics materials to define friction and bounciness; provided as standard assets. Note.. Put rigidbodies on game objects that both move and collide - that react to collisions and other forces (e.g., gravity). 25 On the implementation of Unity Unity is closed-source, source, so we cannot but guess at its actual internal implementation (and anyway, it keeps changing) Unity engine is itself written in C/C++ but game logic is expressed via scripts (C#, UnityScript) Generally, a component-based engine supports well user interfaces that use drag-and-drop-style game creation any component can be handled both in the editor and by script code All scripts are compiled to a.net.dll file (i.e., an assembly) - and finally to native code - so script languages tend to behave rather alike, except perhaps differences in compile-time vs. run-time typing/binding UnityScript and C# are compiled into different assemblies so you can't just refer to one from the other (messy compilation orders..) 26 Unity system architecture (hypothetical sketch only) [by Petri Veijonen] Unity physics is based on a version of the PhysX physics simulation engine; implementing/installing your own would be a major undertaking! 27