Emanuele Feronato

Talking about Flash and Users contributions.

If you code a lot with the same language, no matter if Java, Php or Actionscript, sooner or later you will find yourself writing the same code you already wrote in a previous project.

This is extremely time-wasting, because forces you to spend your time writing routines you have already written some time ago and does not let you totally focus on the script.

That’s why most programmers develop custom functions performing tasks they have to solve in almost every project

Andre Marianiello decided to share with us some useful Flash custom functions.

This is what he sent me by email:

I have compiled some useful functions for flash, and I was wondering if you would like to see them or put them on your blog for your readers. I can provide the .as file with comments and create examples if you want.

These functions include:

– line collision detection
– a useful replacement for the Object.toString() method
– cloning function to copy Objects and Arrays
– plus some trig functions that are often used in your tutorials

All functions come in a .as file plenty of comments. Let’s see it:

Object.prototype.toString = function() {
	//set empty string to be displayed
	var string = "";
	//cycle through properties and functions
	for (var i in this) {
		//if not a function
		if (typeof (this[i]) != "function") {
			//add the property name and value to the string
			string += i+":"+this[i].toString()+", ";
		} else {
			//else add the function name and "Function"
			string += i+":Function, ";
		}
	}
	//don't include last comma and space in final string
	string = string.substring(0, string.length-2);
	return string;
};
MovieClip.prototype.lineHitTest = function(x1, y1, x2, y2, pre) {
	//find difference in x
	var x = x1-x2;
	//find difference in y
	var y = y1-y2;
	//find distance between points
	var dis = Math.sqrt(x*x+y*y);
	//when pre(precision) equals 2, it checks every 2 points
	//therefore, the number of point equals dis/pre
	var num = dis/pre;
	//vars to hold current point
	var tx, ty;
	for (var i = 1; i<=num; i++) {
		//if pre equals 2 and distance is ten, then 
		//we find a point 1/5 of the way down the line.
		tx = x2+i*x/num;
		ty = y2+i*y/num;
		//if the point(tx, ty) touches the movieclip we're testing
		if (this.hitTest(tx, ty)) {
			//return true because the movieclip is on the line
			return true;
		}
	}
	//return false because none of the tested points hit the movieclip
	return false;
};
Object.prototype.clone = function() {
	//empty object
	var temp = new Object();
	//for each propety in the going-to-be-cloned object
	for (i in this) {
		//copy property name with value to new object
		temp[i] = this[i];
	}
	return temp;
};
Array.prototype.clone = function() {
	//empty array
	var temp = new Array();
	//for each value in the going-to-be-cloned array
	for (i in this) {
		//copy value with index to new object
		temp[i] = this[i];
	}
	return temp;
};
angleFromTo = function (x1, y1, x2, y2) {
	//find change in x
	var x = x2-x1;
	//find change in y
	var y = y2-y1;
	//Math.atan2 returns angle in radians; Math.PI/180 converts to degrees
	return Math.atan2(y, x)/(Math.PI/180);
};
distanceFromTo = function (x1, y1, x2, y2) {
	//find change in x
	var x = x2-x1;
	//find change in y
	var y = y2-y1;
	//use pythagorean theorem to find distance
	return Math.sqrt(x*x+y*y);
};
vectorToHorz = function (ang, dis) {
	var rads = ang/(180/Math.PI);
	//returns x-component of a vector of dis magnitude at ang angle
	return dis*Math.cos(rads);
};
vectorToVert = function (ang, dis) {
	var rads = ang/(180/Math.PI);
	//returns y-component of a vector of dis magnitude at ang angle
	return dis*Math.sin(rads);
};

Andre also provided three examples to demonstrate how to use the functions

Let's see the actionscript and the results:

Example 1

#include "customFunctions.as"
arrow.onEnterFrame = function() {
	this._rotation = 0;
	var ang = angleFromTo(0, 0, this._xmouse, this._ymouse);
	var dis = distanceFromTo(0, 0, this._xmouse, this._ymouse);
	xm.text = (this._xmouse);
	funcbox.text = "vectorToHorz("+Math.round(ang)+", "+Math.round(dis)+")";
	vth.text = Math.round(vectorToHorz(ang, dis));
	ym.text = (this._ymouse);
	funcbox2.text = "vectorToVert("+Math.round(ang)+", "+Math.round(dis)+")";
	vtv.text = Math.round(vectorToVert(ang, dis));
	this._rotation = ang;
};

Example 2

#include "customFunctions.as"
ball.onEnterFrame = function() {
	x1 = Math.random()*Stage.width;
	y1 = Math.random()*Stage.height;
	x2 = Math.random()*Stage.width;
	y2 = Math.random()*Stage.height;
	hit = this.lineHitTest(x1, y1, x2, y2, 4);
	_root.clear();
	_root.lineStyle(3, 0x209702);
	_root.moveTo(x1, y1);
	_root.lineTo(x2, y2);
	if (hit) {
		hitbox.text = "hit";
	} else {
		hitbox.text = "no hit";
	}
};

Example 3

#include "customFunctions.as"
num.onChanged = function() {
	testObj.num = this.text;
	updateString();
};
str.onChanged = function() {
	testObj.str = this.text;
	updateString();
};
but1.onRelease = function() {
	testObj.bool = true;
	updateString();
};
but2.onRelease = function() {
	testObj.bool = false;
	updateString();
};
updateString = function () {
	string.text = testObj.toString();
};

testObj = {num:5, str:"test", bool:true};
num.text = testObj.num;
str.text = testObj.str;
num.restrict = "0-9";
updateString();

Sharing custom functions is really a good idea... do you use custom functions in your scripts? Do you want to share them? It would be nice to have a library full of useful custom functions.

This is the zipped archive sent me by Andre, give him feedback