MiniGame1: GrandPrix Monaco

You will:

  • Read the doc

  • Manage Input

  • Control a car by translation/rotation

  • Create obstacles

  • Create a chase camera

  • End the race

Unity doc

How can we find information?

Rotate function

For example, if we want to learn more about the Rotate function, we can search in different ways:

  • Google search: « Unity Rotate function »

  • Search in Unity API

  • Browse the class hierarchy

    ../_images/doc.png

Vector3

Find the documentation about the Vector3 class. You must find this page:

../_images/vector3.png

Refresher

How to manage your view:

  • F key: center an object.

  • Right-click: look around.

  • ALT + Left-click: rotate camera while focusing on the selected object.

  • ALT + Right-click: zoom in & out.

  • Mouse wheel: zoom in & out.

  • Hold mouse wheel + mouse move: pan.

Car Controls

Scene Layout

  • In the Assets folder, create a new folder named MiniGames

  • Inside this folder, create a new Scene named: Ultimate Race

  • Using 3D Cubes:

    • Create a road of 100mx10m

    • Create a car 4mx2mx1m

    • Some obstacles on the road 1mx1mx1m

    ../_images/scene2.png

  • Move your camera so that we can see the whole scene in play mode

Input.GetAxis()

To simplify the code, Unity combines keyboard controls and joystick controls through the Input object. Thus, by using the member function GetAxis(« Horizontal »), we request information about the horizontal control: left/right arrow keys and left/right joystick.

  • Create a new script for the car

  • Paste the following code

using UnityEngine;

public class carcontrol : MonoBehaviour
{
        void Start() { }

        void Update()
        {
                float v = Input.GetAxis("Horizontal");
                Debug.Log(v);
        }
}

  • Run and check the values returned by the GetAxis function

    • Check the range of values returned by the GetAxis function.

    • How many different values are returned?

    ../_images/joy.png

Note

Unity seems to simulate joystick behavior through keyboard keys. For example, when we press the right arrow key, Unity smooths the return values from 0 to 1.

Physic’s law

In unity, rotations use degrees. If a rotation speed is set to 180°/s, it means that our object completes a full turn in 2 seconds or a half turn in 1 second.

We recall the formula that gives the rotation angle based on the rotation speed and the time interval:

\[angle = dT \times Rot_{speed}\]

Let’s turn

We want to make our vehicle rotate at a maximum speed of 30°/sec.

  • Add a public float variable turnSpeed in your script

  • In the update() function, add these lines:

    float dt =  Time.deltaTime;
float hInput = Input.GetAxis("Horizontal");
transform.Rotate( ... );

  • Check the documentation of the Rotate function

  • Using a simple operation, make it so that:

    • When input is 0, nothing happens

    • When input is 1, the vehicle turns at the speed turnSpeed

../_images/rot1.gif
Help in case nothing works
using UnityEngine;

public class carcontrol : MonoBehaviour
{
        public float rotSpeed;

        void Start() { }

        void Update()
        {
                float dT     = Time.deltaTime;
                float hInput = Input.GetAxis("Horizontal");
                transform.Rotate(Vector3.up, rotSpeed * dT * hInput);
        }
}

Go forward

We want our vehicle to drive at a maximum speed of 10m/s.

  • Add a public float variable maxSpeed in your script

  • Check the documentation for Vector3:

    • Find a shorthand that matches a forward-oriented vector.

    ../_images/short.png

  • Check the documentation for Transform.translate():

../_images/doctranslate.png

  • Make it so that:

    • By default, nothing happens

    • When the player press the up arrow key, the vehicle goes forward at the speed maxSpeed

../_images/go.gif

Collision

  • Attach a rigidbody component to the vehicle and to the obstacles.

    • Adjust their weights to match their actual weights.

    • Activate gravity

  • Check that both elements have a mesh collider activated.

  • Run and check your result:

    ../_images/collision.gif

Chase camera

We want the camera to follow the vehicle

../_images/finalcar.gif

  • In the Hierarchy, drag and drop the camera into the car GameObject

    • The camera becomes a child object of the car in the Hierarchy

    • This way, when the car moves, the camera automatically follows

../_images/child.png

  • Reset the camera transform node

  • Activate camera preview

  • Select translate tool

  • Move the camera to position it above the car’s roof with a downward view

../_images/chase.png

Finish line

  • Create a finish line

    ../_images/finish.png

  • Create a collider with a script to detect when the car passes between the two poles

    • Change the color of the banner from red to green