At 10:33 09/06/99 -0400, you wrote:
>On Tue, 8 Jun 1999, Tony Burrows wrote:
>
>> At 13:07 08/06/99 -0400, you wrote:
>> >Hi,
>> >
>> >I have a behavior that changes rotation (in x, y and z) and translation
>> >(in x and z) above ViewPlatform. Basically, it acts like a camera
>> >orientation/position controller. It works most of the time but sometimes,
>> >I get "BadTransformException: non-congruent transform above ViewPlatform"
>> >error message. I seem to get this randomly. Please let me know what's
>> >causing this and anyway of fixing this. Thanks in advance.
>> >
>> >-Tachio
>> 'non-congruent transform means' that you are scaling differently on the
>> axes Tachio (rather than translating). This is OK on the object side of
>> the scene graph, but is not allowed on the view side. Somewhere in the API
>> specs (and I can't remember where) it says that trying to scale the view
>> platform transform in a non-uniform way is not allowed, so you get the
>> exception.
>>
>> Tony
>
>That's strange, I have only rotation/translation transforms above
>ViewPlatform. Well, I hope it was a bug in 1.1.1 which 1.1.2 fixed.
>
>-Tachio
>
A bug in the API is quite possible Tachio - it wouldn't be the first. And
I suppose there could be some other reason for the exception - hard to tell
without the code. But 'non-congruent' does mean scaling according to the
published API and my maths books. I'm far from an expert in matrix
operations though. Maybe there's someone out there who can suggest how a
scaling can be produced from other ops. if it isn't just a bug.
Tony
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