[Bf-committers] Proposed Noise Modifier

[Patrice Gmail]

Hello,  I have submitted a patch for a proposed "noise modifier". Hope 
it gets some (positive) feedback !   And a question regarding deform vs 
non-deform modifier is included at the end.   Many thanks.

Here's what it does:

The "Noise Modifier" will make it possible to add some randomness into 
mesh objects, duplicated objects and arrays of objects.

It may be used in one of three modes, or scopes.

In vertex mode, each individual vertex will be shifted by a random 
amount, somewhere between zero and the set maximum. The probability that 
a given vertex is altered can be defined, and the scope of the modifier 
can be limited to a vertex group, with vertex weight acting as a 
multiplier to the translation.

In whole mesh mode, the mesh is transformed as a whole, while it's 
origin remains. Transformation may be a combination of translation, 
rotation and scaling. This is mostly useful when duplicating objects, 
either with Shift-D or Alt-D. However, for each object to have it's own 
random transformation, the "Use ID as seed" checkbox must be used.

Finally, the loose parts mode is used mostly with arrays of objects. 
Indeed, this appears to be the only way one can add randomness into 
arrays, due to the way the modifier stack operates. Each loose part, 
i.e. set of vertices connected by edges, will be transformed as a whole.

I do have one area where I would like the advice of experienced 
developpers, that is whether to make it a deform or a non-deform 
modifier. In theory, it is deform only, meaning vertices are just moved 
around, never created, and neither are edges and faces. But deform-only 
modifiers receive as input an array of vertex coordinates, not the 
actual BMVert objects. For Vertex mode and Whole Mesh Mode, I could do 
with a deform-only modifier, which is probably a lighter modifier in 
terms of memory usage. But for loose parts mode, I need to identify 
loose parts by walking the mesh through BMW_CONNECTED_VERTEX, which I 
did not manage to do with deform-only. So I switched to non-deform 
modifier. Don't know exactly how much of an issue this is.

Other than this, the only features that are not included at this point 
is rotation and scaling in loose parts mode. It will require finding the 
bounding box center for each loose part.