Half-baked API (Camera position)

Pavel Safrata pavel.safrata at oracle.com
Wed Oct 16 12:37:07 PDT 2013

As I've said, we intend to fix it in the future, so the situation should 
not be impossible. It is mostly used that way in the existing code, but 
there definitely are precedents for throwing it just temporarily. For 

         throw new UnsupportedOperationException("Not supported yet.");


         throw new UnsupportedOperationException("Not supported yet.");
(internal but directly accessible to users via contains())


On 16.10.2013 20:10, Stephen F Northover wrote:
> I took a quick look through JavaFX to find how this exception is used. 
> It is mostly used to indicate impossible situation.  Is that the 
> situation we have here?
> Personally, for me, if we throw the exception, then we will generally 
> just leave it that way forever.
> Steve
> On 2013-10-16 11:22 AM, Pavel Safrata wrote:
>> On 16.10.2013 17:03, Stephen F Northover wrote:
>>> Could do something useful with what was there now?  We can always 
>>> fix this in future by adding another API to govern the 
>>> interpretation of the value.
>> Not much useful. Anyway, any such stuff can be quite easily done by 
>> reading the intersectedPoint's Z coordinate.
>>> Throwing the exception indicates that the call is unsupported, but 
>>> application code can be written to catch the exception and when we 
>>> implement the API, it can break (I realize that this is unlikely).
>> The exception can tell by the message that the operation will be 
>> supported in the future.
>> Pavel
>>> Steve
>>> On 2013-10-16 10:46 AM, Richard Bair wrote:
>>>> My quick vote would be throwing the exception, but is like to hear 
>>>> from Steve and Kevin.
>>>>> On Oct 16, 2013, at 1:04 AM, Pavel Safrata 
>>>>> <pavel.safrata at oracle.com> wrote:
>>>>> Hello,
>>>>> it looks like we can't help releasing a not-fully-baked piece of 
>>>>> API with FX8. We've added bunch of new APIs for 3D and did our 
>>>>> best to make them work well. Unfortunately, there's been not 
>>>>> enough time&priority to fine-tune their behavior in 2D world. 
>>>>> Right now I'm concerned about camera position in scene. It is 
>>>>> inherent in the 3D perspective camera that it has its specific 
>>>>> position in world, but the 2D parallel camera as we have it 
>>>>> projects everything to the XY plane basically by ignoring the Z 
>>>>> coordinate, so the camera position doesn't matter all that much. 
>>>>> However, some of the newly added APIs depend on it:
>>>>> 1. Near/far clip on camera. This obviously cannot work without 
>>>>> knowing where the camera is. Right now the parallel camera does no 
>>>>> clipping though, so I guess we are OK to go with it as a "known 
>>>>> limitation".
>>>>> 2. PickResult on events which reports "intersectedDistance" 
>>>>> between the camera and the picked point. This is worse because we 
>>>>> can't just "not support" it - there will be some value and once 
>>>>> somebody uses it we'll have a backward compatibility issue. The 
>>>>> state right now is that the camera is (tentatively, by my 
>>>>> arbitrary decision) at [0, 0, -1] and reports distances from there 
>>>>> (note that as the camera renders everything, for nodes "in front 
>>>>> of Z=-1" it reports negative distances). This may change when the 
>>>>> camera position is properly discussed and specified.
>>>>> Note that this post is *not* meant to discuss the camera position. 
>>>>> Even if we could find the answer quickly (which I doubt), it's 
>>>>> most probably too late to apply the change for FX8.
>>>>> So finally here is my question: do you think it's OK to solve this 
>>>>> by keeping the current behavior and documenting the 
>>>>> "intersectedDistance" in a way that for parallel camera the 
>>>>> numbers are unspecified and subject to change in future versions? 
>>>>> Or would you prefer something more drastic like throwing an 
>>>>> UnsupportedOperationException (losing the possibility to compare 
>>>>> the distances)?
>>>>> Thanks,
>>>>> Pavel

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