[Bf-committers] derived mesh in modifier stack

Steve Obbayi steve at sobbayi.com
Sun Oct 10 21:04:58 CEST 2010

Hi Tobias, I've taken a quick peek and it looks like get_dm() and get_cddm() return 
copies of the original or derived mesh and therefore leave the originals untouched. So i dont 
think you will find updated vertices from either of these functions.

It only makes sense so that when you remove the modifier it can revert to the original
mesh. Someone else can hopefully clarify.

Steve Obbayi

----- Original Message -----
From: "Tobias Oelgarte" <tobias.oelgarte at googlemail.com>
To: bf-committers at blender.org
Sent: Sunday, October 10, 2010 6:46:50 PM GMT +03:00 Iraq
Subject: [Bf-committers] derived mesh in modifier stack


As far as i found out, a DerivedMesh is created as soon as some modifier 
needs to construct its own geometry. There are the utility functions 
get_dm() and get_cddm() in MOD_util. What is their purpose? I looked at 
what they are doing and it looked like get_cddm() would ensure a 
DerivedMesh is created. But somehow it does not update the vertices and 

How im supposed to access the vertex normals that would exist after the 
last modifier worked on them, before my own modifier, if it is just a 
deform modifier, that does not deliver a new DerivedMesh?

In other words: Can i update the DerivedMesh passed to deformVerts()? Or 
is there a better way to access the current normal data? Vertices seam 
not to be updated after get_dm() or get_cddm().

Best wishes Tobias Oelgarte
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