One (of many) details that's not obvious is the accounting of vertices inside
the GeoInfo and its importance in maintaining any vertex attribute arrays. If
you add additional vertices to a primitive *after* the primitive has already
been added to the GeoInfo (via GeoInfo::add_primitive()) then vertex attribute
array sizes can get out of sync possibly causing a crash.
So until that's fixed make sure to completely build your primitive first before
adding it to the GeoInfo.
-jonathan
On Apr 19, 2011, at 11:55 AM, Nhat Phong Tran wrote:
> Well first you need to add an object which holds your primitives (i.e.
> a polygon) to your output GeometryList. You can do this like this:
>
> out.addObject(yourObjectID);
>
> Now that you have an object created, you can add your primitives to
> it, in your case a polygon.
>
> out.add_primitive(obj, new Polygon(0, 1, 2, 3));
>
> So this allocates a polygon class and assigns points 0-3 to be its
> vertices. But this doesn't mean that the polygon's shape has been
> defined yet, because the points 0-3 have not a set position yet. To do
> this you create a pointer to the pointlist that contains the points of
> your object, then you need to resize the pointlist to fit all of your
> primitives points. Then you iterate through the points of the polygon
> of your interest and set the coordinates of each point.
>
> PointList* points = out.writable_points(yourObjectID);
> points->resize(num_points);
>
> for(unsigned int p=0; p<4; p++){
> (*points)[p].set(x_pos, y_pos, z_pos);
> }
>
> Hope this helps!
>
>
> Nhat
>
>
> ----------------------------------------------------------
> nhat phong tran
> dipl. digital artist (FH)
> computer graphics & visual effects
>
> m_us: +1 (310) 866-6871
> m_de: +49 (176) 24 26 34 27
> fax: +49 (321) 213 25 866
>
> santa monica, ca 90401
>
> sent via iPhone
> ----------------------------------------------------------
>
>
> On 19 April 2011 09:07, Stephen Newbold <stephe...@moving-picture.com> wrote:
>> Hi. Anybody know of any easy to understand documentation on how to create
>> polygons using the NDK? I had a look through the Sphere.cpp example that
>> ships with Nuke and like most things it went completely over my head. I'm
>> hoping to be able to create something simple, just a four sided poly defined
>> by 4 corner points, but have zero idea on how to go about it.
>>
>> Cheers,
>> Steve
>>
>> --
>> Stephen Newbold
>> Senior Compositor - Film
>> MPC
>> 127 Wardour Street
>> Soho, London, W1F 0NL
>> Main - + 44 (0) 20 7434 3100
>> www.moving-picture.com
>>
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