I2DInput

Introduction

The I2DInput interface can be used to generalize input code for detecting a value and velocity along two dimensions (X and Y). A common usage of this is to control an object’s 2-dimensional movement such as a character in a top-down game. Examples of input devices implemented as I2DInput are the GamePad AnalogStick and the GamePad DPad.

The X and Y properties typically return values between -1 and 1.

Code Example – Implementing Movement

The following shows how to move an entity horizontally and vertically using I2DInput. It assumes that the code has an Entity called Character. Note – this example assumes your entity does not already implement the Top Down input movement in Glue. If it does, you will have compile errors.

In Character.cs:
using FlatRedBall.Input;

namespace ProjectName.Entities
{
    public partial class Character
    {
        public I2DInput MovementInput
        {
            get;
            set;
        }

        private void CustomInitialize()
        {
        }

        private void CustomActivity()
        {
            // This would normally be a Glue variable, but added
            // here to keep the example simpler
            float movementSpeed = 100;
            this.XVelocity = MovementInput.X * movementSpeed;
            this.YVelocity = MovementInput.Y * movementSpeed;
        }

        private void CustomDestroy()
        {
        }

        private static void CustomLoadStaticContent(string contentManagerName)
        {
        }
    }
}
In the Screen’s CustomInitialize, assuming it has a CharacterInstance:
// This sets up the movement to use the Up, Down, Left, and Right arrow keys, but any keys could be used
CharacterInstance.MovementInput= InputManager.Keyboard.Get2DInput(Keys.Left, Keys.Right, Keys.Up, Keys.Down);

Common Usage

The following shows how to use the most common FRB input classes to get a I2DInput:

Keyboard
var input = InputManager.Keyboard.Get2DInput(Keys.Left, Keys.Right, Keys.Up, Keys.Down);
Xbox360GamePad DPad
var input = InputManager.Xbox360GamePads[0].DPad;
Xbox360GamePad AnalogStick
var input = InputManager.Xbox360GamePads[0].LeftStick;

 

Magnitude

The Magnitude property returns the distance away from (0,0) that is returned by the input device. By default most input devices return an X and Y value of (0,0) which would indicate a magnitude of 0. If the values are non-zero, then the magnitude will also be non-zero. Typically the Magnitude is between 0 and 1.

Or Extension Method

I2DInput provides an extension method for combining multiple controls. The Or method allows combining multiple input devices to create a single I2DInput instance. For example, you may be developing a game where the player can be moved with both the keyboard and gamepad.

When multiple inputs are combined using Or, the largest of either inputs will be used. For example, if one input device returns an X of 0.5f, and the other returns an X value of 1, then the value of 1 will be returned by the combined

Or Code Example

 

var keyboardInput = InputManager.Keyboard.Get2DInput(
    Microsoft.Xna.Framework.Input.Keys.LeftControl,
    Microsoft.Xna.Framework.Input.Keys.RightControl,
    Microsoft.Xna.Framework.Input.Keys.Up,
    Microsoft.Xna.Framework.Input.Keys.Down);

var analogStickInput = InputManager.Xbox360GamePads[0].LeftStick;

var combined = keyboardInput.Or(analogStickInput);
// combined is an I2DInput which can be used like any other I2DInput