When the player presses a jump button, we want the velocity change to happed exactly once. For single instantaneous events, putting the code in Update is equivalent to writing code that would activate once in the next FixedUpdate.Why is the class static? By marking a class as static you require that its contents are static as well. There can't be any nonstatic variables or methods and it cannot be used to create object instances. In other words, a static class is not a blueprint for objects.What's a delegate? Besides simple values and object references, you also store method references in a variable.
Such a variable is known as a delegate.You define a delegate type as if you're creating a method, except there's no code body. After that, you can use this type to create a delegate variable, to which you can assign any method that matches the type. In fact, you can treat a delegate like a list and add multiple methods to it.
All of them will be called when you invoke the variable. AngularVelocityThe angular velocity vector of the rigidbody measured in radians per second. CenterOfMassThe center of mass relative to the transform's origin. CollisionDetectionModeThe Rigidbody's collision detection mode. ConstraintsControls which degrees of freedom are allowed for the simulation of this Rigidbody.
DetectCollisionsShould collision detection be enabled? FreezeRotationControls whether physics will change the rotation of the object. InertiaTensorThe inertia tensor of this body, defined as a diagonal matrix in a reference frame positioned at this body's center of mass and rotated by Rigidbody.inertiaTensorRotation. InertiaTensorRotationThe rotation of the inertia tensor.
InterpolationInterpolation allows you to smooth out the effect of running physics at a fixed frame rate. IsKinematicControls whether physics affects the rigidbody. MaxAngularVelocityThe maximimum angular velocity of the rigidbody measured in radians per second. MaxDepenetrationVelocityMaximum velocity of a rigidbody when moving out of penetrating state.
SleepThresholdThe mass-normalized energy threshold, below which objects start going to sleep. SolverIterationsThe solverIterations determines how accurately Rigidbody joints and collision contacts are resolved. SolverVelocityIterationsThe solverVelocityIterations affects how how accurately Rigidbody joints and collision contacts are resolved. UseGravityControls whether gravity affects this rigidbody.
It represents the rate of change of Rigidbody position. WorldCenterOfMassThe center of mass of the rigidbody in world space . A prefab is a Unity object – or hierarchy of objects – that doesn't exist in the scene and hasn't been activated. You use it as a template, creating clones of it and adding those to the scene.What does Instantiate do?
The Object class, which every MonoBehaviour inherits from, contains the static Instantiate method. This method creates a clone of whateverObject instance you pass to it. Optionally, you can supply a new position and rotation for the clone, otherwise it keeps the values of the original.Note that Instantiate returns an Object reference. If you want to do something with the new clone, you have to cast it to the correct type. Prototyping and implementation of functionality in Unity is quite easy.
You can easily drag and drop any references to other objects, address every single object in the scene, and access every component it has. On top of noticeable performance issues , there is also great danger in making parts of your code entirely dependent on each other. Or being dependent on other systems and scripts unique to your application, or even on the current scene, or current scenario. Try to take a more modular approach and create reusable parts which can be used in other parts of your application, or even shared across your whole application portfolio. Build your framework and libraries on top of Unity API the same way you are building your knowledge base. A collider is a physics concept used by Unity's physics engine.
They can function as either obstacles, causing collisions, or detectors, triggering events.Why remove the colliders? Because the cubes will be used for the noninteractive background only, nothing will ever collide with then. There's no point in the physics engine keeping track of their colliders, so we simply remove them.What's a material?
Materials are used to define the visual properties of objects. They can range from very simple, like a constant color, to very complex.Materials consist of a shader and whatever data the shader needs. Shaders are basically scripts that tell the graphics card how an object's polygons should be drawn. Now whenever the user applies x-axis input, the rigidbody will move appropriately. Rigidbody velocity calculations handle the application of time to the formula for us.
All we need to do is supply a speed multiple to the input vector. Without a speed multiple, the object will move one unit per second while input is applied. ProcessActions() simply reads in inputs and applies movement and turning. We clamp the inputs of turn and move between -1 and 1 to prevent unintended super-speed.
Moving is done by actually changing the position of the character . There is no force applied, so friction is ignored and the character technically has no velocity. Collisions still work perfectly in the tests I've done. Jumping requires a check to make sure we allow jumping and that the character is grounded, but then applies an upward velocity to the character via rigidbody.AddForce(). There's a lot of different approaches to ensure this.
A good starting point is the Unity component system itself. Complications may appear when particular components need to communicate with other systems of the application. For this, you can use interfaces to make parts of your system more abstract and reusable. It should be exclusively its controller's responsibility.
AddExplosionForceApplies a force to a rigidbody that simulates explosion effects. As a result this will apply a torque and force on the object. AddRelativeForceAdds a force to the rigidbody relative to its coordinate system. AddRelativeTorqueAdds a torque to the rigidbody relative to its coordinate system.
ClosestPointOnBoundsThe closest point to the bounding box of the attached colliders. GetPointVelocityThe velocity of the rigidbody at the point worldPoint in global space. GetRelativePointVelocityThe velocity relative to the rigidbody at the point relativePoint.
MovePositionMoves the kinematic Rigidbody towards position. ResetCenterOfMassReset the center of mass of the rigidbody. ResetInertiaTensorReset the inertia tensor value and rotation. SetDensitySets the mass based on the attached colliders assuming a constant density. SleepForces a rigidbody to sleep at least one frame.
SweepTestTests if a rigidbody would collide with anything, if it was moved through the Scene. SweepTestAllLike Rigidbody.SweepTest, but returns all hits. It's a common mistake, when we add a dynamic or static Rigidbody 2D to an object, if we start the game the object will fall out of the screen. To avoid this we can either place a floor underneath with a collider, or set the gravity value attribute in the rigidbody component to 0. When sleeping, computation of these objects drops significantly and will stay that way until they are utilized again. It's important to add a Rigidbody component to objects you will be moving around in game, even if they will not be moved using forces.
Objects without a Rigidbody are considered static colliders and should not be moved. You can still move them, but it'll come at a drastic performance cost. Set Rigidbody components to "is Kinematic" if you'd like to move them on your own without physics.
Learn more about how to use Physics in Unity in our Fundamentals of Physics course. You must indicate which type of analytical surface is being created and assign a name to the surface. Analytical rigid surfaces are useful when the cross-sections of the surfaces can be represented by straight and curved line segments. The curved segments can be either circular or parabolic arcs.
In two-dimensional simulations the line segments are defined in the global coordinate system of the deformable model. In three-dimensional simulations a local, two-dimensional coordinate system must be created, and the line segments are then defined in that system. The two standard types of three-dimensional analytical rigid surfaces available are shown in Figure 1. A kinematic rigidbody will not be moved by the physics engine. However, other things will still react to it appropriately.
In a way, it's a physics object that defies the laws of physics.What's Quaternion.identity? Quaternion.identity is a static property that corresponds to the identity quaternion, which results in no rotation.Why a specular shader? The default specular shader works like the diffuse shader, except that it also has a specular color and a shininess value.
The shader uses these to add a highlight to the visuals.We use this shader for Booster because it results in more vivid color changes while it rotates. Physic materials are like regular materials, except they deal with collision instead of visual properties. When objects collide, what happens depends on whether they're made of stone, wood, ice, rubber, or some other substance. You use physic materials to simulate this behavior by configuring friction and bounciness.When is FixedUpdate called?
The physics engine works by dividing time into little discrete steps – by default 0.02 seconds – during which it moves objects and then checks for collisions and triggers. It keeps doing that in a loop until it has caught up with real time.The FixedUpdate method works like Update, except that it's called once per physics step instead of once per frame. In other words, FixedUpdate is independent of the frame rate. We want Runner to be disabled before the first game is started, though we want the camera inside of it to stay active. Disabling the runner means we have to deactivate its renderer and the runner component itself. We also switch its rigidbody to kinematic mode to freeze it in place.
We can do this in its Start method, then undo this change when the game-start event is triggered, and then redo it when the game-over event is triggered. We'll also remember its starting position so we can reset it each game start. Let's reset distanceTraveled too, so it's immediately up to date. In this example, our aim is to make our object jump when we click the screen.
We have to apply the force only one time and also we have to prevent applying the force while the object is not touching the ground. Therefore, we are going to check by using two boolean variables, if the object is already in jumping condition and is grounded. Here, I also remind you again that it is a good practice to write anything which is related to physics calculations into the FixedUpdate() method. Hence, we will detect the mouse click in the Update() function, but execute the Jump() method in FixedUpdate() function. All we need to do is take input information and apply a jump force variable to our rigidbody's y-axis velocity while maintaining whatever x-axis velocity may already exist.
The main difference is we need to make sure we are touching the ground when we jump. We're not using Unity's Character Controller component this time, so there's not a convenient "isGrounded" property to ask about. Integrating this character controller with ML-Agents is really simple.
This code assumes your agent is set up to use DiscreteActions, but ContinuousActions should be even easier, since you just need to feed the values directly in . A rigid body is one that is directly controlled by the physics engine in order to simulate the behavior of physical objects. In order to define the shape of the body, it must have one or more Shape objects assigned. Note that setting the position of these shapes will affect the body's center of mass. Don't use performance intensive things in update loops, use caching instead.
A typical example is an access to components or other objects in a scene or intensive calculations in your scripts. If possible, cache everything in Awake() methods, or change your architecture to a more event-driven approach to trigger things just when they're needed. In a script, the FixedUpdate function is recommended as the place to apply forces and change Rigidbody settings .
The reason for this is that physics updates are carried out in measured time steps that don't coincide with the frame update. FixedUpdate is called immediately before each physics update and so any changes made there will be processed directly. Many curved geometries can be modeled exactly with analytical rigid surfaces because of the ability to parameterize the surface with curved line segments. The result is a smoother surface description, which can reduce contact noise and provide a better approximation to the physical contact constraint. The ToString method can be used to create string representations of data. The first conversion is simply the decimal representation of the number .
