# Re: Re: Arc shape

goddard at seznam.cz goddard at seznam.cz
Wed May 2 11:11:41 PDT 2012

```Hello,

thanks for the replies. I clearly misunderstood the API:
"The start angle defines where the angle starts so it doesn't effect
(and shouldn't be subtracted from) the arc length."

Apologies, Jiri

------------ Původní zpráva ------------
Od: Dr. Michael Paus <mp at jugs.org>
Předmět: Re: Arc shape
Datum: 02.5.2012 19:04:31
----------------------------------------
There is a verbal description in the JavaDoc of the Node classs
Transformation section.

Hint: An image would say more than a thousand words.

Am 02.05.2012 18:42, schrieb Jeff Martin:
> Good point. :-). I'm not even sure which way the z-axis goes. Is there a
document on the JavaFX coordinate system?
>
> jeff
>
>
> On May 2, 2012, at 11:17 AM, Dr. Michael Paus wrote:
>
>> But if z would come out of the screen and x is to the right, then y would be
going up according to the right hand rule.
>>
>> Am 02.05.2012 18:06, schrieb Jeff Martin:
>>> I think rotation is following the right hand coordinate system (or right
hand thumb rule) with positive z coming out of the screen.
>>>
>>> The StartAngle also seems to be working correctly according to a sanity test
I just did. The start angle defines where the angle starts so it doesn't effect
(and shouldn't be subtracted from) the arc length.
>>>
>>> jeff
>>>
>>> On May 2, 2012, at 7:26 AM, goddard at seznam.cz wrote:
>>>
>>>> Hi,
>>>>
>>>> I've got this constructor for an arc:
>>>>
>>>> Arc a = new Arc(100f, 100f, 50f, 50f, 0f, 120f); //cX, cY, rX, rY, angle,
>>>> length
>>>>
>>>> That produces the visual output you can see in the attached screenshot.
>>>> My questions are:
>>>> - if the 0 degree starts at X axis, then why?
>>>> - if an arc is extended counter-clockwise, then why?
>>>>
>>>> Does it ignore the startAngle completely?
>>>>
>>>> Arc a2 = new Arc(200f, 100f, 50f, 50f, 120f, 240f); //produces an arc of
>>>>
>>>> There're other things/properties that are designed to use the clockwise
system
>>>> (top, right, bottom, left) in JavaFX, therefore this makes a programmer to
>>>> "switch" between these two concepts, in addition to all the other things
one
>>>> must remember.
>>>> I think we had similar discussion during JavaFX 1.2 or 1.3 development...
>>>>
>>>> Regards, Jiri
>>
>> --
>>
--------------------------------------------------------------------------------------
>> Dr. Michael Paus, Chairman of the Java User Group Stuttgart e.V. (JUGS).
>>

--
--------------------------------------------------------------------------------------
Dr. Michael Paus, Chairman of the Java User Group Stuttgart e.V. (JUGS).