I'm getting the same crazy, I don't know what's going on results using this. Is there something I'm missing?
Yeah -- and without that, none of your previous attempts had a chance to succeed. :) _rotation takes degrees, i.e., where a full circle is 360. Math.sin and Math.cos take radians, where a full circle is 2 * Math.PI. You have to convert: var rad = r / 180 * Math.PI; then: var c = Math.cos( rad ); var s = Math.sin( rad ); That's all. Sorry, I should have mentioned it. Mark On 10/5/06, Jason C Reynolds <[EMAIL PROTECTED]> wrote:
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" <[email protected]> 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 >> _______________________________________________ >> [email protected] >> To change your subscription options or search the archive: >> http://chattyfig.figleaf.com/mailman/listinfo/flashcoders >> >> Brought to you by Fig Leaf Software >> Premier Authorized Adobe Consulting and Training >> http://www.figleaf.com >> http://training.figleaf.com >> > _______________________________________________ > [email protected] > To change your subscription options or search the archive: > http://chattyfig.figleaf.com/mailman/listinfo/flashcoders > > Brought to you by Fig Leaf Software > Premier Authorized Adobe Consulting and Training > http://www.figleaf.com > http://training.figleaf.com > > _______________________________________________ [email protected] To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
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