[Bf-committers] getMeshDerivedMesh recomputes object->data
stephane.soppera at wanadoo.fr
Sat Aug 26 20:16:28 CEST 2006
Hum... does somebody know something about this issue?
Stephane SOPPERA a écrit :
> I was trying with python Mesh module to give values of vertices
> normals on a newly created mesh.
> I noticed that it's impossible and investigated the problem.
> Actually after the script is ended, since a new object and a new mesh
> have been created, object_handle_update function calls
> makeDispListMesh for the new object. makeDispListMesh then involves
> this call stack:
> and in getMeshDerivedMesh there is a call to mesh_calc_normals with
> mdm->verts=me->verts and vertCos=NULL
> This call recomputes the normals for each vertex (me->verts) of the
> original data.
> Actually there is also a comment before the code:
> // XXX this is kinda hacky because we shouldn't really be
> // the mesh here, however, we can't just call
> // because in the case when a key is applied to a mesh the
> vertex normals
> // would never be correctly computed.
> mesh_calc_normals(mdm->verts, me->totvert, me->mface,
> me->totface, &mdm->nors);
> mdm->freeNors = 1;
> So the consequence of all that is that each time the display mesh is
> generated (this happen at least when an object is created and each
> time the modifier stack is modified), original mesh normals are
> recomputed and their previous value is lost.
> Is this a wanted behavior? Or is it a side effect?
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