Creating the Puck Entity

Introduction

Now that we have our PlayerBall movement working, we'll add a Puck Entity which the user can hit around. You'll find that the Puck is very similar to the PlayerBall.

Creating a Puck Entity

To create a Puck Entity:

1. Click on the Quick Actions tab

2. Click the Add Entity button

3. Name the Entity Puck

4. Check the Circle check box under Collisions

5. Verify that ICollidable is checked (it should be checked automatically when Circle is checked)

   

   Options for creating a Puck entity
6. Click OK

The Puck entity should appear in the FlatRedBall Editor.

For more information on how to perform the above steps, you may want to review the tutorial which created the first entity (Player).

Differentiating the Puck

Currently our Puck and PlayerBall both have Circle bodies, and by default the Circles have the same size and color. To differentiate the Puck from the PlayerBall:

1. Expand the Puck entity

2. Click on the CircleInstance object under the Puck Entity

3. Click the Variables tab

4. Find the Color variable

5. Change the value to Red using the drop-down

6. Change the Radius value to 6

Computer settings matter: If your computer is set up so the decimal separator is the comma ',' instead of the period '.' then you should enter values using the ',' character. Unlike C# code, Glue obeys your computer's language settings.

PuckList in GameScreen

By default the FlatRedBall Editor adds lists of newly-created entities to the GameScreen. Therefore, you should already have a PuckList in your GameScreen.

If you unchecked the option, or if you would like to know how to manually add a PuckList to your GameScreen, the following section shows how to add a list. This is not necessary if you kept the defaults.

(Optional) Adding a PuckList Manually

1. Click the Puck entity

2. Select the Quick Actions tab

3. Click the Add Puck List to GameScreen button

   

Adding a Puck Instance

1. Select the Puck entity

2. Click the Add Puck Instance to GameScreen button

   

Now the GameScreen has a list and a single Puck.

Positioning your objects

If you run your game you'll notice that the PlayerBallInstance and PuckInstance are both at the center of the Screen. Let's reposition the PlayerBall1:

1. Select the PlayerBall1 object under your GameScreen

2. Change the X value to -180

Puck Collision

Now that we have a Puck in our game, we need to create two collision relationships:

1. Puck vs Walls - this prevents the Puck from moving through the walls.

2. Puck vs PlayerBall - this allows the PlayerBall to "hit" the puck to try to score a goal. We haven't yet created the handling of goals, but this is the first step towards implementing that feature.

We create these two collision relationships just like the previous PlayerListVsWall collision relationship. To create a relationship between the PuckList and Wall:

1. Expand GameScreen's Objects folder in Glue

2. Drag+drop the PuckList onto the Walls object

3. Select the new PuckVsWalls collision relationship

4. Select the Collisions tab

5. Set the Collision Physics to Bounce

6. Change the Puck Mass to 0

7. Optionally adjust the Elasticity value

To create a relationship between the PuckList and PlayerBallList:

1. Expand GameScreen's Objects folder in Glue

2. Drag+drop the PlayerBallList onto the PuckList object

3. Select the new PlayerBallVsPuck collision relationship

4. Select the Collisions tab

5. Set the Collision Physics to Bounce

6. Change the Puck Mass to 0.3 - this makes it 30% the mass of the PlayerBall

7. Optionally adjust the Elasticity value

Notice that the mass variables for PlayerInstance vs. PuckInstance differ compared to wall collision. The PuckInstance is given a mass of .3 relative to a mass of 1 for the PlayerInstance, resulting in the PuckInstance behaving as if it has 30% of the mass of the PlayerInstance. If you run the game, you should be able to hit the Puck around the level.

Adding Drag

Currently the Puck moves indefinitely after being hit. We'll assign the Drag value to the Puck just like we did to PlayerBall:

1. Select the Puck Entity in Glue

2. Select the Variables tab

3. Click the Add New Variable button

4. Select the Expose an existing variable option

5. Select the value Drag

6. Enter a value of 0.4 for Drag

Now the Puck slows down over time just like the PlayerBall.