[osg-users] transforming between coordinate systems of two subgraph

[Christian Buchner]

Also I think it has to be a 4 element vector (last element being 1.0), no?
We're working in homogeneous coordinates here.

I was having additional trouble because I noticed my chosen transformation
objects were actually PositionAttitudeTransforms which don't derive from
the MatrixTransform class (these PAT objects don't even provide utility
function to return an equivalent transformation. But I got that sorted out
eventually.

Christian

2015-07-16 18:43 GMT+02:00 Glenn Waldron <gwaldron at gmail.com>:

> NP. One more thing I forgot to mention. Convert coordB to a osg::Vec3d
> first. Otherwise you risk losing precision. (Because geometry coords are
> 32-bit float, while transform matrices are 64-bit double.)
>
> Glenn Waldron / @glennwaldron
>
> On Thu, Jul 16, 2015 at 12:36 PM, Christian Buchner <
> christian.buchner at gmail.com> wrote:
>
>> Hi,
>>
>> thanks a lot. Now that I've got the solution in front of me, I must
>> say.... that was obvious ;)
>>
>> Christian
>>
>>
>> 2015-07-16 17:35 GMT+02:00 Glenn Waldron <gwaldron at gmail.com>:
>>
>>> coordA = (coordB * matrixTransformB->getMatrix()) * matrixTransformA
>>> ->getMatrix().inverse();
>>>
>>>
>>>
>>> Glenn Waldron / @glennwaldron
>>>
>>> On Thu, Jul 16, 2015 at 11:23 AM, Christian Buchner <
>>> christian.buchner at gmail.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> I was having some problems with a coordinate transformation.
>>>>
>>>> root
>>>> matrixTransformA      matrixTransformB
>>>> subgraphA                subgraph B
>>>>
>>>> I have two subgraphs in my scene, each of which is a child of a unique
>>>> MatrixTransform.
>>>>
>>>> I now have to draw a line between an element from subgraph A to connect
>>>> to an element of subgraph B. I've decided to add this line into subgraphA
>>>> as a drawable - so both start and end point of this line have to be
>>>> specified in my "A" coordinate system.
>>>>
>>>> How would I transform a coordinate from subgraph B coordinate system
>>>> into the equivalent
>>>> coordinate valid within subgraph A, ideally using utility functions
>>>> provided by the OSG framework ? I would like to do that with minimal amount
>>>> of code.
>>>>
>>>> Excuse me for asking a basic linear algebra question, but I seem to be
>>>> stuck for good on this problem.
>>>>
>>>> Christian
>>>>
>>>>
>>>>
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>>>>
>>>
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