On 3/2/07, Karina Steffens <[EMAIL PROTECTED]> wrote:
If your mc's reg point is top left: mc._x = _root.xmouse - mc._width/2 mc._y = _root.ymouse - mc._height/2
Incidentally, there's a neat trick you can do to speed up the calculation AND ensure that the result is an integer (so that the clip is aligned to the pixel). It's called "bitwise shift right": mc._x = _root.xmouse - (mc._width >> 1); mc._y = _root.ymouse - (mc._height >> 1); The benefit in speed is probably negligible in this case. In a test where I ran a calculation a million times, shift right was about 200ms faster than division. (I wonder if the difference might be greater in AS3, though....) However, if you also have to constrain to an integer (e.g., using Math.floor()), then shift right is over twice as fast as using Math.floor and division. Basically, whenever multiplying or dividing by a power of 2, you can use shift left (for multiplication) or shift right (for division) and get a faster result that is automatically constrained to an integer. x >> 1 is equivalent to Math.floor(x / 2) x >> 2 is equivalent to Math.floor(x / 4) x >> 3 is equivalent to Math.floor(x / 8) x >> 4 is equivalent to Math.floor(x / 16) x << 1 is equivalent to Math.floor(x * 2) x << 2 is equivalent to Math.floor(x * 4) x << 3 is equivalent to Math.floor(x * 8) x << 4 is equivalent to Math.floor(x * 16) You get the idea.... -- T. Michael Keesey Director of Technology Exopolis, Inc. 2894 Rowena Avenue Ste. B Los Angeles, California 90039 -- The Dinosauricon: http://dino.lm.com Parry & Carney: http://parryandcarney.com ISPN Forum: http://www.phylonames.org/forum/ _______________________________________________ Flashcoders@chattyfig.figleaf.com 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
