Introduction

This tutorial provides information on how to change the input device used by the entity. By default the entity uses the first Xbox game pad if one is available, otherwise the entity uses the keyboard. Sometimes this functionality is not desired, such as if the game supports multiple players or AI-controlled entities.

IInputDevice

The Top Down entity code interacts with the IInputDevice interface, which provides a standard set of values for controlling game objects. Both the Xbox360GamePad and Keyboard implement this interface, so if the default implementation for this interface meets your game's needs, you can use these objects as-is. Otherwise, your game can implement its own IInputDevice to change how the top down entity is controlled. First we'll look at how to customize the input to use different keyboard keys.

Changing Input Keys

As mentioned earlier, our Player entity defaults to using an Xbox gamepad if one exists. If not, it uses the keyboard. Even though we won't customize this code, we can see its implementation by looking in Player.Generated.cs and searching for InitializeInput.

Ultimately, these calls make their way to calling CustomInitializeTopDownInput. Since this is a partial method, we need to add it ourselves to our Player if we want to customize the input. To do this:

1. Go to Player.cs

2. Add the following code to the Player.cs file

The player will now move around with the IJKL keys (rather than the default WASD). Note that this will also override input even if you have an Xbox gamepad plugged in. If this is not desired, we can change the input if it's using the keyboard. This is an example of how to keep the input device, but only change the movement code conditionally:

This code could contain further updates to change desired input based on other input devices such as Xbox360GamePad.

Changing Input Device

The code in the section above modifies which keys are used from the keyboard. It could be expanded to also handle other input devices like Xbox gamepads. However, instead of changing which keys are used when using the keyboard, you may want to change which input device is being used by your player. This is typically done in the GameScreen. This allows the GameScreen to initialize input, especially if your game allows the player to pick which input device to use. For example, to force the player to always use an Xbox gamepad, modify the following code in the GameScreen's CustomInitialize:

Creating Multiple Players

If your game followed the previous tutorials, then your GameScreen has a PlayerList with a single Player named Player1. In this setup, the GameScreen will always have at least 1 player, but can have more. A quick way to support multiplayer without any UI is to detect the number of Xbox gamepads plugged in. If more than 1 is plugged in, we can create additional players very easily. The following code will create one player per Xbox gamepad plugged in. Notice that we only create additional players if we have two or more gamepads since the first player is automatically created.

To see more than one player you must have at least two gamepads plugged in to your computer. Also, keep in mind that the players will initially overlap so you must move one to see both.

Introduction

The CurrentMovement property controls the values used by the top down entity in response to input. The CurrentMovement property can be assigned in code in response to various conditions in your game such as:

• Collision with different terrain (such as walking through mud)

• Responding to power-ups (such as collecting a power-up which increases speed)

• Responding to special moves or input which changes the character's movement variables (such as holding down a run button)

Defining Movement Values

Movement values can be defined in the FRB editor or code. If your game has a limited set of movement values, these can be defined in the FRB editor. To do so:

1. Select an entity

2. Click the Entity Input Movement tab

3. Verify that your entity is using the Top Down option for Input Movement Type

The Top Down tab displays all movement values for the selected entity.

Assigning Movement Values

You can assign the current movement values in code through the CurrentMovement propety. For example, the following code assigns the movement to FastMovement or Default depending on the state of an Xbox360GamePad:

Movement Values and Inheritance

Derived entities can override movement values which are defined by their base entity. For example, consider an Enemy entity with two movement types: Idle and Walk.

A derived entity automatically inherits these movement values as shown in the FRB editor.

Notice that these values are read-only, but they can be overwritten by checking the Overwrite Values radio button.

The name of movement types cannot be changed when overwriting values; however derived entities can add additional movement variables which do not exist in their base.

At runtime the derived entity merges the overwritten values with the base values. For example, the Slime enemy has two movement values, but its Walk value has a max speed of 150 instead of 76.

Introduction

This tutorial sets up an entity with Top Down controls. It provides a default implementation which requires no code. Later tutorials show how to interact with this plugin using code.