Hoping you can elaborate just a bit with this... I've created just a simple
test movie for this just using code in the timeline.
I have a movieclip 'myBox', which is 50X100, and located at 0,0 on the
stage. Then I put a circle movie clip 'myDot', which hopefully will be
following that bottom center point I'm trying to get at. Taking your
example, this is what it comes to:
var r=-45;
myBox._rotation = r;
var x = myBox._width / 2;
var y = myBox._height;
var c = Math.cos(r);
var s = Math.sin(r);
var rotX = c * x - s * y;
var rotY = s * x + c * y;
myDot._x = rotX - myBox._width;
myDot._y = rotY - myBox._height;
I'm getting the same crazy, I don't know what's going on results using this.
Is there something I'm missing?
Thanks everyone for the replies, much appreciated!!!
----- Original Message -----
From: "Mark Winterhalder" <[EMAIL PROTECTED]>
To: "Flashcoders mailing list" <flashcoders@chattyfig.figleaf.com>
Sent: Wednesday, October 04, 2006 7:19 PM
Subject: Re: [Flashcoders] Find point after rotation
Lets say I have a rectangle (height > width). I need to know the bottom
middle point. That would be point(clipWidth / 2, clipHeight).
So we'll say:
var x = clipWidth / 2;
var y = clipHeight;
Closest I've gotten is using:
x=ClipWidth / 2 + Math.cos(angle)
y=ClipWidth / 2 - Math.sin(angle)
That's pretty close already -- it's what you would use to draw a
circle (by iterating the angle and connecting the resulting dots).
What you need is those two values:
var cos = Math.cos( angle );
var sin = Math.sin( angle );
Then do the following with x and y from above (your "vector" for the
"rotation matrix"):
var rotX = cos * x - sin * y;
var rotY = sin * x + cos * y;
rotX and rotY are your coordinates (relative to the rectangle clip's
position on its parent clip).
One more thing:
_rotation is stored as one byte, so it's rounded to 360 / 255. That's
something you will have to take in account for the angle if you want
to be exact, easiest would be to read the angle from the _rotation
property after you've changed that.
HTH,
Mark
On 10/4/06, Jason C Reynolds <[EMAIL PROTECTED]> wrote:
Hi, having some math problems... hoping someone can help....
Lets say I have a rectangle (height > width). I need to know the bottom
middle point. That would be point(clipWidth / 2, clipHeight).
But I am having a hard time keeping track of this point after I rotate
that clip. If I rotate the clip 40 degrees (clip._rotation = -40), where
on the stage is that bottom middle point now?
I have searched the forums, and came up with alot of finding the angles,
but all seem to assume I know 2 points.
Closest I've gotten is using:
x=ClipWidth / 2 + Math.cos(angle)
y=ClipWidth / 2 - Math.sin(angle)
Sorry, I'm soooo rusty with math and hoping someone can push me in the
right direction. Right now I'm trying to figure out the radius of the
'circle' that is formed while rotating, but that isn't going anywhere
(fast anway).
Thanks for any tips,
Jason
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