Detecting the Mouse Angle - Page 2

Trig Refresher

Ever want to go back and do some high school Trigonometry again? Oh boy is this the right place.

Comment: ----------------------------------------------
Comment:          Manually Set Movie Center
Comment: ----------------------------------------------
Comment: also set the origin of the line object movie clip to this number
Set Variable: "scr_ctr_x" = 200
Set Variable: "scr_ctr_y" = 200
Comment: ----------------------------------------------
Comment:     lookup table for sine values
Comment: ----------------------------------------------
Set Variable: "sine_lookup_table" = "0.000/.0175/.0349/.0523/.0698/.0872/
.1045/.1219/.1392/.1564/.1736/.1908/.2079/.2250/.2419/.2588/.2756/.2924/
.3090/.3256/.3420/.3584/.3746/.3907/.4067/.4226/.4384/.4540/.4695/.4848/
.5000/.5150/.5299/.5446/.5592/.5736/.5878/.6018/.6157/.6428/.6561/.6691/
.6820/.6947/.7071/.7193/.7314/.7431/.7547/.7660/.7771/.7880/.7986/.8090/
.8192/.8290/.8387/.8480/.8572/.8660/.8746/.8829/.8910/.8988/.9063/.9135/
.9205/.9272/.9336/.9397/.9455/.9511/.9563/.9613/.9659/.9703/.9744/.9781/
.9816/.9848/.9877/.9903/.9925/.9945/.9962/.9976/.9986/.9994/.9998/1.000"

Above is the "variable" frame on the main timeline. In it, we need to set the 0,0 point of the effect. The reason is, Flash's 0,0 point is at the top left hand corner of the movieboard. Since my movie is 400x400 the point 200,200 is a convenient point to centre the effect on. The 0,0 point of the "pointer line" is also at 200,200. Notice the way that movie clip is built. You will see that the little "plus" sign (the origin) is at the point of the artwork around which the rotation will occur. We will use these variables later.

The other important thing you need is a sine lookup table. Why? You need to do some trig! Since Sin(Theta)=O/Hyp and since this relationship is always constant (in other words, it doesn't matter what length 'O' and 'Hyp' are, their proportions will always be the same when the angle between them is the same.) Hey. I may not be the best at explaining this stuff. I only re-learned it the other day from :

http://library.thinkquest.org/20991/home.html - Go here if you aren't up on trig.