drawgear.as

AS3的画图功能一些源码

/*-------------------------------------------------------------
	mc.drawGear is a method that draws gears... you
	know, cogs with teeth and a hole in the middle where
	the axle goes? Okay, okay... so nobody *needs* a
	method to draw a gear. I know that this is probably
	one of my least useful methods. But it was an easy
	adaptation of the polygon method so I did it anyway.
	Enjoy. FYI: if you modify this to draw the hole
	polygon in the opposite direction, it will remain
	transparent if the gear is used for a mask.
-------------------------------------------------------------*/
MovieClip.prototype.drawGear = function(x, y, sides, innerRadius, outerRadius, angle, holeSides, holeRadius) {
	// ==============
	// mc.drawGear() - by Ric Ewing ([e-mail]) - version 1.3 - 3.5.2002
	// 
	// x, y = center of gear.
	// sides = number of teeth on gear. (must be > 2)
	// innerRadius = radius of the indent of the teeth.
	// outerRadius = outer radius of the teeth.
	// angle = [optional] starting angle in degrees. Defaults to 0.
	// holeSides = [optional] draw a polygonal hole with this many sides (must be > 2)
	// holeRadius = [optional] size of hole. Default = innerRadius/3.
	// ==============
	if(arguments<5) {
		return;
	}
	if (sides>2) {
		// init vars
		var step, qtrStep, start, n, dx, dy;
		// calculate length of sides
		step = (Math.PI*2)/sides;
		qtrStep = step/4;
		// calculate starting angle in radians
		start = (angle/180)*Math.PI;
		this.moveTo(x+(Math.cos(start)*outerRadius), y-(Math.sin(start)*outerRadius));
		// draw lines
		for (n=1; n<=sides; n++) {
			dx = x+Math.cos(start+(step*n)-(qtrStep*3))*innerRadius;
			dy = y-Math.sin(start+(step*n)-(qtrStep*3))*innerRadius;
			this.lineTo(dx, dy);
			dx = x+Math.cos(start+(step*n)-(qtrStep*2))*innerRadius;
			dy = y-Math.sin(start+(step*n)-(qtrStep*2))*innerRadius;
			this.lineTo(dx, dy);
			dx = x+Math.cos(start+(step*n)-qtrStep)*outerRadius;
			dy = y-Math.sin(start+(step*n)-qtrStep)*outerRadius;
			this.lineTo(dx, dy);
			dx = x+Math.cos(start+(step*n))*outerRadius;
			dy = y-Math.sin(start+(step*n))*outerRadius;
			this.lineTo(dx, dy);
		}
		// This is complete overkill... but I had it done already. :)
		if (holeSides>2) {
			if(holeRadius == undefined) {
				holeRadius = innerRadius/3;
			}
			step = (Math.PI*2)/holeSides;
			this.moveTo(x+(Math.cos(start)*holeRadius), y-(Math.sin(start)*holeRadius));
			for (n=1; n<=holeSides; n++) {
				dx = x+Math.cos(start+(step*n))*holeRadius;
				dy = y-Math.sin(start+(step*n))*holeRadius;
				this.lineTo(dx, dy);
			}
		}
	}
};