Actionscript 3 object collision to prevent character overlapping - actionscript-3

Question

Me and my friend are trying to make an rpg-style game where you see your character from above but we've run into some trouble with object collision. Might be worth mentioning we're doing this in an object oriented AS3 project in flash CS6.
I'm sorry if this has been asked a million times but we've been looking for solutions all day and what we've found so far has either been stuff that's a bit too advanced for us like box2d/nape or just plain collision detection which we know already.
The problem we have is that we want a convenient way to detect collision and prevent the main character from overlapping with objects in the scene, without having it freeze up or get stuck. So far we've scrapped all attempts at solving the issue but here's the rest of the code in case that helps you understand where we're at(sorry if it's difficult to read). Any kind of suggestions or referral to relevant tutorials is appreciated.
The main class
package {
import flash.display.Stage;
import flash.display.MovieClip;
import flash.events.Event;
public class Engine extends MovieClip
{
private var hero:Hero;
private var box1:Box1;
public function Engine()
{
box1 = new Box1();
stage.addChild(box1);
box1.x = stage.stageWidth / 4;
box1.y = stage.stageHeight / 2;
hero = new Hero(stage, box1);
stage.addChild(hero);
hero.x = stage.stageWidth / 2;
hero.y = stage.stageHeight / 2;
}
}
}
The character class
package
{
import flash.display.MovieClip;
import flash.events.Event;
import flash.display.Stage;
public class Hero extends MovieClip
{
private var box1:Box1;
private var stageRef:Stage;
private var vy:Number = 0;
private var vx:Number = 0;
private var limit:Number = 30;
private var rad:Number;
private var bounce:Number = 0.125;
private var _max:Number = 8;
public function Hero(stageRef:Stage, box1:Box1)
{
//box variable was used in previous experiments with hit tests
this.box1 = box1;
this.stageRef = stageRef;
Input.initialize(stageRef);
stageRef.addEventListener(Event.ENTER_FRAME, moveHero);
}
private function moveHero(e:Event):void
{
if (Input.kd("W","UP"))
{
vy = vy < 1 - _max ? _max * -1:vy - 1;
}
if (Input.kd("S","DOWN"))
{
vy = vy > _max - 1 ? _max:vy + 1;
}
else if (!Input.kd("W", "UP", "S", "DOWN"))
{
if (vy > 1)
{
vy = vy < 1 ? 0:vy - 1;
}
else
{
vy = vy > -1 ? 0:vy + 1;
}
}
if (Input.kd("A","LEFT"))
{
vx = vx < 1 - _max ? _max * -1:vx - 1;
}
if (Input.kd("D","RIGHT"))
{
vx = vx > _max - 1 ? _max:vx + 1;
}
else if (!Input.kd("A", "LEFT", "D", "RIGHT"))
{
if (vx > 1)
{
vx = vx < 1 ? 0:vx - 1;
}
else
{
vx = vx > -1 ? 0:vx + 1;
}
}
if (x < limit)
{
x = limit;
vx *= - bounce;
}
if (x > stage.stageWidth - limit)
{
x = stage.stageWidth - limit;
vx *= - bounce;
}
if (y < limit)
{
y = limit;
vy *= - bounce;
}
if (y > stage.stageHeight - limit)
{
y = stage.stageHeight - limit;
vy *= - bounce;
}
x += vx;
y += vy;
rad = (Math.atan2(stage.mouseY - y,stage.mouseX - x)) * 180 / Math.PI;
this.rotation = rad;
}
}
}

Answer 1

A simple way to do collision detection is:
1) Attempt to move the object X to its new position
2) For each other object in the game Y, compute if Y and X overlap (will use different algorithms for rectangle in circle, rectangle in rectangle, circle in circle, etc)
3) If they do overlap, go back to step 1 but attempt to move it half as far. ALTERNATIVELY: If the object you collided with was round, alter the angle of movement to go tangential to it while making it smaller according to how much you rotated it by (the cosine of the angle change, so 0x for 90 degree changes, (sqrt2/2)x for 45 degree changes and 1x for 0 degree changes, makes sense in my head.)
4) If your move was successful, keep it. If the movement length is growing incredibly small and is still being rejected, assume you are at rest and give up.
More complex algorithms would eject you away from the center of what you collided with, so you'll curve around curved objects by walking into them and so on, but then you have to be careful that the ejection doesn't collide you with a third object Z, and it can get tricky. (Have you considered using a physics library? They're coded for a good reason - physics is hard to get right.)