The player can navigate clockwise or counter-clockwise around the circumference of the circle while dodging oncoming obstacles which fly towards the player's avatar at high-speeds.
Features and Implementations
Objects grow in size and speed as they move away from the middle of the screen creating a 3D illusion. This was done using a constant speed variable throughout the application that was used to update object positions, sizes, and opacity exponentially with each frame render.
Randomly Picked Patterns
Instead of randomly generating obstacle paths, which would occasionally send obstacles flying down the same few paths multiple times due to the random nature of randomness, I decided to write several short, pre-determined patterns. Those patters were stored in an array and executed one at a time. Once a pattern had completed it's lifecycle, another pattern was then chosen at random to maintain an unpredictable experience.
Efficient Collision Detection
Since the ship's distance from the center of the circle is constant and the positions the ship can occupy are limited and relatively small in number, I chose to implement a minimal form of collision detection.
Rather than keep track of the ship's and each object's occupied coordinates and their areas, I instead kept track of each of the eight section's states. Sections are stored in an object with their id as a key and state as a boolean value of each key. If an obstacle's outer radius is greater than that of the radius of the ship's front and it's inner radius is less than that of the ship's back, that section becomes a "danger" section. If the ship exists in a section while it is in a "danger" state, the player takes damage for each frame that it maintains a "danger" state.
This checks each obstacle and if it is in a "danger zone" it's section's "danger" state is set to
true and the id is pushed to a local array. Otherwise if the obstacle is not in a "danger zone" and it's section is not included in the current array of
deathPaths it changes it's section's "danger state" to
false. Lastly any section that has no obstacle currently in it has it's "danger" state reset to
The game was first designed to be played on a keyboard with left and right keys. But I wanted mobile users to be able to enjoy the game as well so I used a simple data query to detect whether the display screen was below a certain size. If it is mobile-sized, left and right touch-buttons will be generated towards the bottom of the screen that provide mobile users the same functionality as the left/right keys on a keyboard.
Efficient Visual Designs
Entities that are numerous in number are kept only while needed in order to preserve memory. Each instance of an Obstacle and/or Star (white specks in the background) are stored in an array that is iterated through to render the object. That array has a limit to it's length and once that limit is reached the array is shifted to remove an old object each time a new object is push on to it.
Object Oriented Programing and Code Organization
From the beginning of this project I held good OOP practices as a high priority. Each class takes care of it's own logic and each visible class has it's own
render() function that was then called only by a parent class in order to comply with the Law of Demeter.
app.js was file was used for the basic page functionality and event listeners. Upon DOM-load it created a new instance of the game class in
spaceflight.js, which in turn took care of general game setup and then rendered each other class in the appropriate order, each class instance took care of it's own positions and drew them on the given
context constant passed down from
app.js. This follows a pattern of "Tell, Don't Ask", in which it is considered good practice to leave logic up to the subject by giving it parameters if need instead of determining what the subject should be doing based on local information.
Because of this good practice, on the case that I decided I needed to refactor my code the effort and time needed for the transition was minimal and issues that popped up were easy to address. Keeping up this practice will be a priority of mine from here on during my career when going into new or existing projects as the effort to keep organized code was minimal and the outcome was ideal.
Future Features may include
Rare generation of a shield regenerating obstacles.
- Gradually increasing obstacle spawn rates.
- Obstacles can spawn more than one at a time.
- Temporary turret upgrade to destroy obstacles.
- Temporary enemy that chases player around circle.
- High score backend database.