# AVI

My website code stuff

Project maintained by Polaros Hosted on GitHub Pages — Theme by mattgraham

# Orbits • Steampage
• Nov 2014 – Mar 2018
• Made with Unity and JavaScript

### Project Description

In senior year of high school, I started a game that I just finished a few months ago. It’s a 2D space arcade game which features 10+ enemies, 100 unique levels featuring those enemies and 20 unique bosses which build on the themes of the surrounding levels. Check out the steam page!

### Code Examples

Possibly my favorite bit of code I’ve ever written, this puts any object into a perfectly circular orbit around a nearby center of gravity. It also saves the starting velocity and distance of that orbit, so they can be corrected if altered.

``````function Orbit ()
{
if (star1 == null && attractor1 == null)
{
return;
}

//Zero out velocity before Orbit
GetComponent.<Rigidbody2D>().velocity = Vector2.zero;
GetComponent.<Rigidbody2D>().angularVelocity = 0;

//location with respect to source of gravity
var ex : double = 0;
var wi : double = 0;
var gravity : double = 15;

ex = transform.position.x -
(star1 ? star1.transform.position.x : attractor1.transform.position.x);
wi = transform.position.y -
(star1 ? star1.transform.position.y : attractor1.transform.position.y);
gravity = (star1 ? star1.gravity : attractor1.gravity);

//Find force for perfect orbit
var force : double = 62 * Mathf.Sqrt((200 *
GetComponent.<Rigidbody2D>().mass * gravity) /
(Mathf.Sqrt((ex * ex) + (wi * wi))));

//If the objects are on top of each other - causing near infinite force
if (force > 100000)
{
return;
}

//Split the required force into x and y components then apply them
if (wi >= 0 && autoOrbit && !reverse) {
Mathf.Cos(Mathf.Atan(ex / wi)));
Mathf.Sin(Mathf.Atan(ex / wi)));
}
else if (wi >= 0 && autoOrbit && reverse) {
Mathf.Cos(Mathf.Atan(ex / wi)));
Mathf.Sin(Mathf.Atan(ex / wi)));
}
else if (wi < 0 && autoOrbit && !reverse) {
Mathf.Cos(Mathf.Atan(ex / wi)));
Mathf.Sin(Mathf.Atan(ex / wi)));
}
else if (wi < 0 && autoOrbit && reverse) {
Mathf.Cos(Mathf.Atan(ex / wi)));
Mathf.Sin(Mathf.Atan(ex / wi)));
}
yield WaitForSeconds(0.2);

//Save starting velocity and distance for correction
startingVel = GetComponent.<Rigidbody2D>().velocity.magnitude;
startingDist = Mathf.Sqrt((ex * ex) + (wi * wi));
}
``````

This function takes in current and original distance and speed then corrects them if they are too far off. It makes it look as though the AI is actively trying to stay in a stable orbit despite the player’s push.

``````function CorrectOrbit()
{
//Calculate the distance off from starting distance
ex = transform.position.x -
(star1 ? star1.transform.position.x : attractor1.transform.position.x);
wi = transform.position.y -
(star1 ? star1.transform.position.y : attractor1.transform.position.y);

//Find the offsets
var offsetDist : double = Mathf.Sqrt((ex * ex) + (wi * wi)) - startingDist;
var offsetVel : double = GetComponent.<Rigidbody2D>().velocity.magnitude -
startingVel;

//Break if the Orbit is beyond helping
if (offsetDist > 20 || offsetDist < -20 ||
offsetVel > 20 || offsetDist < -20)
{
CancelInvoke();
return;
}

//Correct the distance
//Apply force towards planet
if (offsetDist > 3)
{
if (ex <= 0)
Push(ex, wi, 1, 1);
else
Push(ex, wi, -1, -1);
}

//Apply force away from planet
else if (offsetDist < -3)
{
if (ex <= 0)
Push(ex, wi, -1, -1);
else
Push(ex, wi, 1, 1);
}

//Correct the speed
//Apply force counter clockwise
if ((!reverse && offsetVel < -3) || (reverse && offsetVel > 3))
{
if (wi >= 0)
Push(ex, wi, -1, 1);
else
Push(ex, wi, 1, -1);
}

//Apply force clockwise
else if ((!reverse && offsetVel > 3) || (reverse && offsetVel < -3))
{
if (wi >= 0)
Push(ex, wi, 1, -1);
else
Push(ex, wi, -1, 1);
}
}

function Push(ex, wi, xDir, yDir)
{
GetComponent.<Rigidbody2D>().AddForce (Vector2.right * correction * xDir *
Mathf.Cos(Mathf.Atan(ex / wi)));
GetComponent.<Rigidbody2D>().AddForce (Vector2.up * correction * yDir *
Mathf.Sin(Mathf.Atan(ex / wi)));
}
``````