213 lines
7.1 KiB
ReStructuredText
213 lines
7.1 KiB
ReStructuredText
.. _doc_scenes_and_nodes:
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Scenes and nodes
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================
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Introduction
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------------
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.. image:: /img/chef.png
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Imagine for a second that you are not a game developer anymore. Instead,
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You are a chef! Change your hipster outfit for a toque and a double
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breasted jacket. Now, instead of making games, you create new and
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delicious recipes for your guests.
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So, how does a chef create a recipe? Recipes are divided in two
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sections, the first is the ingredients and the second is the
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instructions to prepare it. This way, anyone can follow the recipe and
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savor your magnificent creation.
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Making games in Godot feels pretty much the same way. Using the engine
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feels like being in a kitchen. In this kitchen, *nodes* are like a
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refrigerator full of fresh ingredients to cook with.
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There are many types of nodes, some show images, others play sound,
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other nodes display 3D models, etc. There's dozens of them.
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Nodes
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-----
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But let's go to the basics. A node is a basic element for creating a
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game, it has the following characteristics:
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- Has a name.
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- Has editable properties.
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- Can receive a callback to process every frame.
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- Can be extended (to have more functions).
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- Can be added to other nodes as children.
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.. image:: /img/tree.png
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The last one is very important. Nodes can have other nodes as
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children. When arranged in this way, the nodes become a **tree**.
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In Godot, the ability to arrange nodes in this way creates a powerful
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tool for organizing the projects. Since different nodes have different
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functions, combining them allows to create more complex functions.
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This is probably not clear yet and it makes little sense, but everything
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will click a few sections ahead. The most important fact to remember for
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now is that nodes exist and can be arranged this way.
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Scenes
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------
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.. image:: /img/scene_tree_example.png
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Now that the existence of nodes has been defined, the next logical
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step is to explain what a Scene is.
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A scene is composed of a group of nodes organized hierarchically (in
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tree fashion). It has the following properties:
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- A scene always has only one root node.
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- Scenes can be saved to disk and loaded back.
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- Scenes can be *instanced* (more on that later).
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- Running a game means running a scene.
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- There can be several scenes in a project, but for it to start, one of
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them must selected to be loaded first.
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Basically, the Godot editor is a **scene editor**. It has plenty of
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tools for editing 2D and 3D scenes as well as user interfaces, but all
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the editor revolves around the concept of editing a scene and the nodes
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that compose it.
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Creating a new project
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----------------------
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Theory is boring, so let's change subject and go practical. Following a
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long tradition in tutorials, the first project will be a hello world.
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For this, the editor will be used.
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When godot executable is run outside a project, the Project Manager
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appears. This helps developers manage their projects.
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.. image:: /img/project_manager.png
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To create a new project, the "New Project" option must be used. Choose
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and create a path for the project and specify the project name:
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.. image:: /img/create_new_project.png
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Editor
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------
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Once the "New Project" is created, the next step is opening it. This
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will open the Godot editor. Here is how the editor looks when freshly
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opened:
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.. image:: /img/empty_editor.png
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As mentioned before, making games in Godot feels like being in a
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kitchen, so let's open the refrigerator and add some fresh nodes to the
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project. We'll begin with a Hello World! To do this, the "New Node"
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button must be pressed:
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.. image:: /img/newnode_button.png
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This will open the Create Node dialog, showing the long list of nodes
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that can be created:
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.. image:: /img/node_classes.png
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From there, select the "Label" node first. Searching for it is probably
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the quickest way:
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.. image:: /img/node_search_label.png
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And finally, create the Label! A lot happens when Create is pressed:
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.. image:: /img/editor_with_label.png
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First of all, the scene is changed to the 2D editor (because Label is
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a 2D Node type), and the Label appears, selected, at the top left
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corner of the viewport.
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The node appears in the scene tree editor (box in the top left
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corner), and the label properties appear in the Inspector (box on the
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right side).
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The next step will be to change the "Text" Property of the label, let's
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change it to "Hello, World!":
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.. image:: /img/hw.png
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Ok, everything's ready to run the scene! Press the PLAY SCENE Button on
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the top bar (or hit F6):
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.. image:: /img/playscene.png
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Aaaand... Oops.
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.. image:: /img/neversaved.png
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Scenes need to be saved to be run, so save the scene to something like
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hello.scn in Scene -> Save:
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.. image:: /img/save_scene.png
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And here's when something funny happens. The file dialog is a special
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file dialog, and only allows to save inside the project. The project
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root is "res://" which means "resource path. This means that files can
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only be saved inside the project. For the future, when doing file
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operations in Godot, remember that "res://" is the resource path, and no
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matter the platform or install location, it is the way to locate where
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resource files are from inside the game.
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After saving the scene and pressing run scene again, the "Hello, World!"
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demo should finally execute:
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.. image:: /img/helloworld.png
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Success!
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.. _doc_scenes_and_nodes-configuring_the_project:
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Configuring the project
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-----------------------
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Ok, It's time to do some configuration to the project. Right now, the
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only way to run something is to execute the current scene. Projects,
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however, have several scenes so one of them must be set as the main
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scene. This scene is the one that will be loaded at the time the project
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is run.
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These settings are all stored in the engine.cfg file, which is a
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plaintext file in win.ini format, for easy editing. There are dozens of
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settings that can be set in that file to alter how a project executes,
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so to make matters simpler, a project setting dialog exists, which is
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sort of a frontend to editing engine.cfg
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To access that dialog, simply go to Scene -> Project Settings.
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Once the window opens, the task will be to select a main scene. This can
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be done easily by changing the application/main_scene property and
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selecting 'hello.scn'.
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.. image:: /img/main_scene.png
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With this change, pressing the regular Play button (or F5) will run the
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project, no matter which scene is being edited.
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Going back to the project settings dialog. This dialog provides a lot
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of options that can be added to engine.cfg and show their default
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values. If the default value is ok, then there isn't any need to
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change it.
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When a value is changed, a tick is marked to the left of the name.
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This means that the property will be saved to the engine.cfg file and
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remembered.
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As a side note, for future reference and a little out of context (this
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is the first tutorial after all!), it is also possible to add custom
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configuration options and read them in run-time using the
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:ref:`Globals <class_Globals>` singleton.
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To be continued...
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------------------
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This tutorial talks about "scenes and nodes", but so far there has been
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only *one* scene and *one* node! Don't worry, the next tutorial will
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deal with that...
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