Asteroids

This project is a recreation (with some personal additions) of the original Atari game Asteroids released in 1979.

Key Features:

Multishot

I first defined totalMultishotAngle as the range that the multishot bullets were to be fired and dispersed at, and multishotLevel as, well, the multishot level.

I then define multishotDivisions as 2 + multishotLevel * 2. The "2+" is to have a base multishot level and each multishot level adds two more bullets (to balance on each side), thus times 2.

Then, I iterate through multishot divisions (i <= multishotDivisions) and use this formula to calculate the angle:

rotatedAngle = angle + totalMultishotAngle/2 - (totalMultishotAngle/multishotDivisions * i)

This diagram explains what is happening in the formula:

Movement and Rotation

Logic:

I used trigonometry to calculate the X and Y speeds depending on a angle value and a "thrust" value.

Rendering:

I used the rotation matrix to rotate the points making up the shape of the ship, which is then rendered.

$$ \begin{bmatrix} \cos(\theta) & -\sin(\theta) \\ \sin(\theta) & \cos(\theta) \\ \end{bmatrix} $$

This can be expressed in (pseudo) code as:

rotatedX = x * cos(angle) - y * sin(angle);
rotatedY = x * sin(angle) + y * cos(angle);

Key Concepts:

• Trigonometry
• Interfaces
• Object-Oriented Programming
• Matrices

Pictures: