I need help understanding how this works. AS 2.0

Question

Its my first time here and i only started learning flash today. I aint too great with maths and i was showed this piece of code that makes a triangles point follow the cursor. It involved mathimatical things ( which i aint so great at) and the guy said "You dont need to know how it works, just how to use it." well i copied his code and it worked, but i have no idea how to use it in other rotation apart from the one he taught us. I dont even understand how to redo his code i saved it to a word document and anytime i wanted to make something rotate something in that fashion i would refer to that. But i dont want to have to do that, i want to know how to use it, dont have to understand it, but use it for other rotation matters. If you are going to help, please try to be a bit simmple i explaining it, cause im new. Dont get me wrong i aint thick but i can find it a bit hard to follow some things, that is i my current problem.
here is the rotation code:
onEnterFrame = function()
hero._rotation = getmouse(hero);
getmouse = function(mc:MovieClip):Number
dy = _ymouse-mc._y;
dx = _xmouse-mc._x;
rad = Math.atan2(dy,dx);
rotate = rad*180/Math.PI
return rotate+90
also if it helps, here is the video i was watching: http://www.youtube.com/watch?v=w3OfrpbNhHs
please if you can, explain how the entire thing works.
thanks for any help given in advance.

Answer 1

Hi,
Here's a short primer.  It may not be sufficient but here goes.
1st, move the closing bracket at the end and put it on the third line.  This makes the code more efficient
onEnterFrame = function(){                               // this causes Flash to repeatedly
                                                                          execute the next line at the
                                                                          frame rate you selected
                                                                          for your document
       hero._rotation = getmouse(hero);               // this tells Flash to rotate a
                                                                          movie clip (named hero) based
                                                                          on the function getmouse()
};                                                                     // putting the }; here makes the
                                                                          code more efficient and readable
getmouse = function(mc:MovieClip):Number{   // This is the function called with
                                                                         mc referring to hero that was
                                                                         passed from the second line.
     dy = _ymouse-mc._y;                                // dy means delta y which subtracts
                                                                        the y position of the movieclip
                                                                        from the mouses y position
     dx = _xmouse-mc._x;                               // dx = delta x (same as above line
                                                                        but on the x axis)
                                                                     // once you have the x and y sides
                                                                        you male a triangle.
                                                                        Now use trig to find the angle
     rad = Math.atan2(dy,dx);                           // the computer works in radians
                                                                        the arc tangent atan2 will give the
                                                                        angle in radians
     rotate = rad*180/Math.PI                            // you want to convert the radians to
                                                                        degrees, that's what this line does
     return rotate+90                                         // this returns the value of rotate back
                                                                        to the calling function in line 2.
                                                                        the +90 determines which part
                                                                    // of the hero movie clip is facing the
                                                                       mouse.
If you put the mouse cursor over any of the green reserved words above in the Actions panel you will get a desctription of what these do.
hope that helps.