RE: [PHP] gd project question

```Good day,

Wow, a high school math question.```
```
You should use asin() and acos() of the angle to get the y and x
differentials, respectively.  Multiply the result by the size of the needle.

This assumes that your guage is oriented horizontally, and the needle sweeps
from right to left, pointing upwards.  Adjust the sign or switch the
functions around if your gauge is different.

Note that the functions operate in radians (2*pi radians == 360 degrees).

============================
Darren Gamble
Planner, Regional Services
Shaw Cablesystems GP
630 - 3rd Avenue SW
T2P 4L4
(403) 781-4948

> -----Original Message-----
> From: Michael Geier [mailto:[EMAIL PROTECTED]]
> Sent: Friday, May 31, 2002 9:18 AM
> To: Php-General
> Subject: [PHP] gd project question
>
>
> I have the following issue:
>
>       I am making a "gas guage" based on a percentage.
>       ie.
>               - a 180 degree arc is created
>               - the range will be 0 to n (undetermined ammount)
>               - there will be x number of entries
>               - the needle will pount to a a percentage
>                 for (int)floor((x / n) * 100)
>
>       The issue is, I have the starting pt for the needle
> (imagefilledarc
>       needs the center of the 'circle' as the starting pt,
> which is where
>       the needle will start too), but how would I get the x|y
> coordinates
>       for the end of the needle based on a perentage of a half-circle
>       (180 degree arc)?
>
> Appreciate any clues or ideas.
>
> ---
> Michael Geier
>
>
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