A physics engine is a system helps to detect the collisions between recreation objects and simulate their motion. That is very helpful once you need to create a recreation that has sensible physics habits. Frequent video games like puzzle video games and platformers use physics engine to create their core gameplay.
One well-known instance is Offended Birds. It makes use of the physics engine to create the projectile of the chook and the sensible fall of the obstacles after destruction.
On this tutorial, you’ll study concerning the fundamentals of Godot 2D physics engine and the best way to use it to construct a Marble drop recreation.
Alongside the way in which, you’ll:
- Study completely different sorts of physics node.
- Find out about PhysicsMaterial and the way it impacts the sport.
- Use RigidBody2D node to create a dynamic physics object.
- Use Area2D node to create a set off.
- Use StatcBody2D node to create a stationary physics object.
- Use Snap to Grid to align the nodes.
- Add sound results and background music to the sport.
The ultimate product of this tutorial is a one-click, physics-based recreation. Gamers click on the taking part in discipline to drop a marble with the purpose to attain as many factors as doable.
On the finish of this tutorial, you’ll know perceive the fundamentals of Godot’s 2D physics engine.
Get Began
This tutorial makes use of the newest steady model of Godot 4. You possibly can obtain it right here.
Obtain the tutorial supplies by clicking Obtain Supplies on the high or backside of the tutorial. Subsequent, extract the zip file to your chosen venture location.
There are two initiatives included within the supplies:
- starter: The starter venture you’ll use to construct upon.
- last: The ultimate model of the sport you possibly can run and play immediately.
This tutorial requires you to have primary data of Godot Engine. If you happen to don’t really feel acquainted with Godot but, attempt these tutorials first:
File Overview
Import and open the starter venture in Godot Undertaking Supervisor. After opening the venture, you’ll discover the ready useful resource information, reminiscent of pictures, sounds, and person interfaces.
The venture construction is as follows:
- fonts: Font information
- music: Background music
-
scenes: Scene information
- game_board.tscn: Sport Board Scene
- game_over_dialog.tscn: GameOver dialog
- gui.tscn: Rating and marble depend Consumer Interface
- main_scene.tscn: Foremost scene
- scripts: Script information
- sounds: Sound results
- sprites: Graphics
- credit score.txt: An inventory of attributions for the included property
Foremost Scene
The Foremost Scene is the scene the place the sport takes place. It accommodates all nodes that want by the sport.
To open it, double-click main_scene.tscn within the FileSystem dock.
Then, swap to the 2D display screen to preview the sport board.
Now, you’ve a grasp of what the venture seems to be like. Subsequent, you’ll study some primary ideas of the physics engine.
Understanding 2D Physics Engine
If you end up creating a recreation, chances are you’ll want the next options to craft the gameplay:
- When two recreation objects collide with others, for instance, when a marble hits a rating set off.
- Management the motion of an object after making use of a power or a collision has occurred. For instance, how the marble bounces off the pegs.
A physics engine is right for this; it gives two main features: Collision Detection and Object Motion Simulation.
Collision Detection
The engine repeatedly checks for overlaps between the physics objects within the scene and sends alerts once they collide.
Object Motion Simulation
The engine simulates the motion of objects based mostly on their physics attributes.
These are the physics attributes in Godot:
- Mass: Determines how forces have an effect on an object.
- Gravity: Applies a downward power to simulate falling.
- Friction: Resists the movement between two surfaces involved.
- Bounce: Determines how a lot velocity is reserved when two our bodies collide.
Now you understand the essential ideas of the physics engine, you possibly can transfer on to study extra concerning the completely different physics nodes provided by Godot.
Understanding Completely different Physics Nodes
Godot presents three fundamental physics nodes: RigidBody2D, StaticBody2D and Area2D. Every node has completely different functions and behaviors and it’s best to select the appropriate one for every recreation ingredient.
-
StaticBody2D: This node doesn’t transfer below physics simulation however can have an effect on RigidBody2D nodes.
It’s used for stationary surroundings objects like pegs and partitions. - RigidBody2D: This node has mass and is actively simulated by the physics engine. It will probably reply to forces, gravity, and collisions. It will probably additionally have an effect on different RigidBody2D nodes.
- Area2D: This node gained’t trigger physics reactions, however it might test for any collisions which have occurred. It’s used for getting into or exiting zones just like the rating set off.
Right here’s a fast comparability between the physics nodes:
With all this in thoughts, it’s time to create your first physics node.
Create a RigidBody2D node
To characterize the marble within the recreation that may fall below gravity, and bounce off pegs, it’s essential to create a RigidBody2D node.
The Marble Scene
To be able to create the marble that can be utilized within the recreation, it’s essential to create a brand new scene for it with RigidBody2D as the basis node. A scene is a group of nodes. On this case, it accommodates a RigidBody2D node for the physics simulation and a Sprite2D node for the look of the marble.
To create the scene, choose the scenes folder within the FileSystem dock. Now right-click and choose Create New ▸ Scene. Whereas the scene creation dialog is open, configure it like this:
- Root Kind: Different Node ▸ RigidBody2D
- Scene Title: marble.tscn
- Root Title: Marble
In regards to the PhysicsMaterial
Proper after creating the RigidBody2D node, it’s essential to configure the PhysicsMaterial of the node. PhysicsMaterial is a setting that defines how the node behave within the physics simulation.
There are two fundamental group of settings within the PhysicsMaterial: Friction and Tough and Bounce and Absorbent. Every group has completely different settings that have an effect on the node’s pace when it collides with one other node.
Friction and Tough
Friction is a quantity between 0 and 1. The upper the worth, the node has extra friction and strikes slower when collide. The decrease the worth, the node has much less friction and seem to slip extra simply.
Tough is a boolean. It controls which friction worth is used among the many two colliding nodes. Listed here are the principles:
- Each nodes Tough worth are ON, the upper friction worth is used.
- Each nodes Tough worth are OFF, the decrease friction worth is used.
- Just one node Tough worth is ON, the physics engine takes the friction worth with tough ON.
The next demonstration reveals how the marble behaves with completely different friction and tough setting.
