This lesson covers how to handle basic keyboard input in Zilch Engine.

Learning Objectives

Checking for keyboard input

Level Setup

Command : New Project
Create a new project using the {nav icon=clone, name=Empty 2D Project} template
Command : CreateSprite
Command : Add Resource
Create a NadaScript resource using the Component template template and name it CharacterLogic
Select : Sprite object
In the Properties Window
Rename Sprite object to Character
Add Component : CharacterLogic

Keyboard Input

A critical part of making a game is to allow the user to interact with it. The simplest way to achieve that is to query the available hardware for input and have the simulation respond to it.

Update the CharacterLogic script to the following code block:

class CharacterLogic : NadaComponent
{
  function Initialize(init : CogInitializer)
  {
    Zilch.Connect(this.Space, Events.LogicUpdate, this.OnLogicUpdate);
  }

  function OnLogicUpdate(event : UpdateEvent)
  {
    if(Zilch.Keyboard.KeyIsPressed(Keys.Space))
    {
      this.Owner.Sprite.VertexColor = Colors.Red;
    }
  }
}

Command : PlayGame
Press key Space

SimpleInput

Command : StopGame

Let's take a closer look inside our if statement:

Zilch.Keyboard.KeyIsPressed(Keys.Space);
Zilch	Accessing the Zilch engine class
Keyboard	Accessing Keyboard class
KeyIsPressed(...);	Function that determines whether a given key has been pressed this frame
Keys	Enumeration containing all keyboard keys
.Space	The enumeration index corresponding to the `Space` key

Here are all Keyboard functions:

Keyboard Functions
KeyIsDown	Checks whether a given key is currently down this frame
KeyIsUp	Checks whether a given key is currently down this frame
KeyIsPressed	Checks whether a given key was pressed this frame
KeyIsReleased	Checks whether a given key was released this frame

(NOTE) Enumerations - An enumeration (or enum) is a data type that groups items assigning each a unique name under the enumerated list. Items can be referenced by accessing the type followed by a . and the name of the desired item (i.e. Keys.Space or Colors.Red). You can read more on enumerations here.

Dynamic Character Controller

Let's use what we just learned to create a character controller for a simple platformer.

Character Setup

Select : Character object
In the Properties Window
Add Component : RigidBody
Add Component : BoxCollider
Under RigidBody
Set RotationLocked checkBox to true

Ground Setup

Command : CreateSprite
Select : Sprite object
In the Properties Window
Rename Sprite object to Ground
Add Component : BoxCollider
Under Transform
Set Translation to 0.0, -3.0, 0.0
Set Scale to 8.0, 0.0, 0.0
Under Sprite
Set SpriteSource texture to Square
Set VertexColor to Green [R:0, G:255, B:0, A:1.00]

Movement Code

In the CharacterLogic script
Replace the previous LogicUpdate function with the following:

function OnLogicUpdate(event : UpdateEvent)
{
  var speed : Real = 5.0;
  var xDir : Real = 0.0;
  
  if(Zilch.Keyboard.KeyIsDown(Keys.Right))
  {
    xDir += 1.0;
  }
  
  if(Zilch.Keyboard.KeyIsDown(Keys.Left))
  {
    xDir += -1.0;
  }
  
  this.Owner.RigidBody.Velocity = Real3(xDir * speed, this.Owner.RigidBody.Velocity.Y, 0.0);
}

Command : PlayGame
Press key Left and Right

CharacterMovement

Command : StopGame

Manual

Reference

Classes

Enums

Keys

Table of Contents

Learning Objectives

Level Setup

Keyboard Input

Dynamic Character Controller

Character Setup

Ground Setup

Movement Code

Manual

Reference

Classes

Enums

Commands

Table of Contents

Learning Objectives

Level Setup

Keyboard Input

Dynamic Character Controller

Character Setup

Ground Setup

Movement Code

Related Materials

Manual

Reference

Classes

Enums

Commands