Principles Of HTML5 Game Design

gistfile1.txt

function point2(x, y)
{
	return {'x': x || 0, 'y': y || 0};
}

function vector2(x, y)
{
	return {'x': x || 0, 'y': y || 0};
}

point2.distance = function(a, b)
{
	var x = a.x - b.x;
	var y = a.y - b.y;
	return Math.sqrt(x*x + y*y);
};

vector2.length = function(vector)
{
	return Math.sqrt(vector.x*vector.x + vector.y*vector.y);
};

vector2.normalize = function(vector)
{
	var length = vector2.length(vector);
	if (length > 0)
		return vector2(vector.x / length, vector.y / length);
	else
		return vector2();
};

point2.direction = function(from, to)
{
	var x = to.x - from.x;
	var y = to.y - from.y;
	var length = Math.sqrt(x*x + y*y);

	if (length > 0) 
		return vector2(x / length, y / length);
	else
		return vector2();
};