Chapter 4
This chapter shows how easy it is to use the object-oriented groundwork created in the previous chapter to create simple games efficiently.
As suggested by the book the following features have been added:
- A start screen
- Tweaking of various game variables for better gameplay
- Limiting laser firing rate
- larger rocks spawn smaller rocks.
- Added a UFO which randomly spawns after some time and randomly appears at an edge traveling through the center of the screen and destroys the spaceship if in contact with it.
- Added a powerup that randomly appears at a time and place, when the spaceship collides with it full shield power is restored.
A game design document (GDD) is a blueprint for creating a game: it describes the overall vision of a game, provide clarity and focus, and serves as a guide and a reference to the people working on the game. A GDD is often based on a framework, such as MDA.
The Mechanics-Dynamics-Aesthetics (MDA) framework is a useful way to categorize the components of a game. In appendix A in the book on page 402, there is a list of GDD questions which are very helpful with the creation of a GDD. The core questions can be summarised as follows:
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Overall Vision
a. Write a short paragraph explaining the game
b. Describe the genre
c. What is the target audience?
d. Why play this game?
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Mechanics: the rules of the game world
a. What are the character's goals?
b. What abilities does the character have?
c. What obstacles or difficulties will the character face?
d. What item can the character obtain
e. What resources must be managed?
f. Describe the game-world environment.
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Dynamics: the interaction between the player and the game mechanics
a. What hardware is required by the game?
b. What type of proficiency will the player need to develop to become proficient at the game?
c. What gameplay data is displayed during the game?
d. What menus, screens, or overlays will there be?
e. How does the player interact with the game at the software level?
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Aesthetics: the visual, audio, narrative, and psychological aspects of the game
a. Describe the style and feel of the game.
b. Does the game use pixel art, line art, or realistic graphics?
c. What style of background music, ambient sounds will the game use?
d. What is the relevant backstory for the game?
e. What emotional state(s) does the game try to provoke?
f. What makes the game fun?
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Development
a. List the team members and their roles, responsibilities, and skills.
b. What equipment is needed for this project?
c. What are the tasks that need to be accomplished to create this game?
d. What points in the development process are suitable for playtesting?
e. What are the plans for publication?
A discrete action happens at a single point in time. E.g actions are triggered the instant a key is pressed.
The InputProcessor interface handles discrete events.
An InputMultiplexer contains a list of InputProcessors, which makes sure every screen overlay will be responsive.
Continuous actions take place over an interval of time. E.g holding down a key for a period of time. Input polling repeatedly checks the status of an input device (such as a keyboard).
import com.badlogic.gdx.InputProcessor - An InputProcessor is used to receive input events from the keyboard and the touch screen (mouse on the desktop). For this, it has to be registered with the Input.setInputProcessor(InputProcessor) method. It will be called each frame before the call to ApplicationListener.render(). Each method returns a boolean in case you want to use this with the InputMultiplexer to chain input processors.
import com.badlogic.gdx.InputMultiplexer - An InputProcessor that delegates to an ordered list of other InputProcessors. Delegation for an event stops if a processor returns true, which indicates that the event was handled.
import com.badlogic.gdx.scenes.scene2d.Group - 2D scene graph node that may contain other actors. Actors have a z-order equal to the order they were inserted into the group. Actors inserted later will be drawn on top of actors added earlier. Touch events that hit more than one actor are distributed to topmost actors first.