ActionScript 3 - Draw two shapes on the same movie clip's graphics avoiding alpha blending between them

Question

for example:

var mc:MovieClip=new MovieClip();

mc.graphics.beginFill(0x000000,0.5);
mc.graphics.drawRect(0,0,100,100);
mc.graphics.endFill();

mc.graphics.beginFill(0x000000,0.5);
mc.graphics.drawRect(0,0,100,100);
mc.graphics.endFill();

with this i will get a box with an alpha value darker than 0.5. I want a 0.5 alpha square without using something like:

var mc:MovieClip=new MovieClip();

mc.graphics.beginFill(0x000000,1);
mc.graphics.drawRect(0,0,100,100);
mc.graphics.endFill();

mc.graphics.beginFill(0x000000,1);
mc.graphics.drawRect(0,0,100,100);
mc.graphics.endFill();

var bmp:BitmapData=new BitmapData(100,100);
bmp.draw(mc);
var mc2:MovieClip=new MovieClip();
mc2.graphics.beginBitmapFill(bmp);
mc2.graphics.drawRect(0,0,100,100);
mc2.graphics.endFill();

obvoiusly i don´t want it for drawing squares, it´s for a shadow casting algorithm i´m working on.

Answer 1

Instead of using alpha ,you could use ColorTransform. With TweenMax , it's pretty easy but of course you could code your own solution.

var mc:MovieClip=new MovieClip();
mc.graphics.beginFill(0xffffff); mc.graphics.drawRect(0,0,100,100); mc.graphics.endFill();
TweenMax.to( mc , 0 , {colorTransform:{tint:0x000000 , tintAmount:.5}} );

mc.graphics.beginFill(0xffffff); mc.graphics.drawRect(0,0,100,100); mc.graphics.endFill();
TweenMax.to( mc , 0 , {colorTransform:{tint:0x000000 , tintAmount:.5}} );

Answer 2

Depending on what you are doing, you can just draw everything as alpha 1, set the alpha of the object itself to 0.5, and then use a LAYER blending mode which flattens the transparency before applying the alpha.

var mc:MovieClip = new MovieClip();
addChild(mc);

var sp:Shape;

sp = new Shape();
sp.graphics.beginFill(0x000000,1);
sp.graphics.drawRect(0,0,100,100);
sp.graphics.endFill();
mc.addChild(sp);

sp = new Shape();
sp.graphics.beginFill(0x000000,1);
sp.graphics.drawRect(50,50,100,100);
sp.graphics.endFill();
mc.addChild(sp);

mc.alpha = 0.5;
mc.blendMode = BlendMode.LAYER;

It's a bit convoluted, but you get the idea.

Using a bitmap would be the best for performance, though. Again, it depends on exactly what you have to implement and how.

Also, depending on what you have to draw, if you can rely on drawPath() instead, you could just use it with winding set to GraphicsPathWinding.NON_ZERO.