[Bf-committers] getMeshDerivedMesh recomputes object->data normals?

[Stephane SOPPERA]

Ben Batt a écrit :
> Hi Stephane,
> It looks to me like mdm->verts needs to be a copy of me->verts. I'll
> have a bit more of a
> poke around and get back to you.
Have you found anything?

Stéphane









>
> Ben
>
> On 8/27/06, Stephane SOPPERA <stephane.soppera at wanadoo.fr> wrote:
>> Hum... does somebody know something about this issue?
>>
>> Stephane SOPPERA a écrit :
>> > Hi,
>> >
>> > 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:
>> > makeDispListMesh
>> >    mesh_build_data
>> >        mesh_calc_modifiers
>> >            getMeshDerivedMesh
>> >
>> > 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
>> > editing
>> >            // the mesh here, however, we can't just call
>> > mesh_build_faceNormals(ob)
>> >            // 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?
>> >
>> > Stéphane
>> >
>> >
>> >
>> >
>> >
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>> >
>>
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