[peengoh]

Hi, all. just today a student came to ask for a constant-volume deformer, and I couldn't give him an answer. He doesn't need anything fancy, I have been trying to find a deformer or an expression to help him.

any help would be appreciated.

[eddgarpv]

The first thing that comes to my mind would be use ncloth and pressure. Or is it volume as in fluids and constant as in linear?

[Doc]

Volume preservation
Nathan did this in Blender for the rabbit in Big Buck Bunny
http://www.bigbuckbunny.org/index.ph...-rigging-demo/

You can download the production files to find out how he did it so you can adapt it to your software
http://www.bigbuckbunny.org/index.php/download/

Another way to simulate this is by using a muscle system.

[negativecitizen]

por si alguin quiere echarle un ojo este es una copia del mencionado script(una especie de huesos musculares) en python:


#BPYCONSTRAINT
'''
Forces a bone to preserve volume by automatically
scaling it along the x and z axis'.

A minimum and maximum bone width can be
defined in constraint settings.
'''

import Blender
from Blender import Draw
from Blender import Mathutils
import math



def doConstraint(obmatrix, targetmatrix, idprop):
# Get the user setting.
if not idprop.has_key('minscale'): idprop['minscale'] = 0.01
if not idprop.has_key('maxscale'): idprop['maxscale'] = 100.0

# Separate out the tranformation components for easy access.
obloc = obmatrix.translationPart() # Translation
obrot = obmatrix.toEuler() # Rotation
obsca = obmatrix.scalePart() # Scale


# Preserve volume!
if obsca.y != 0:
scale = min( max( 1 / math.fabs( obsca.y ), idprop['minscale'] ), idprop['maxscale'] )
obsca.x = obsca.z = scale


# Convert back into a matrix for loc, scale, rotation,
mtxloc = Mathutils.TranslationMatrix( obloc )
mtxrot = obrot.toMatrix().resize4x4()
mtxsca = Mathutils.Matrix([obsca[0],0,0,0], [0,obsca[1],0,0], [0,0,obsca[2],0], [0,0,0,1])

# Recombine the separate elements into a transform matrix.
outputmatrix = mtxsca * mtxrot * mtxloc

# Return the new matrix.
return outputmatrix





def getSettings(idprop):
if not idprop.has_key('minscale'): idprop['minscale'] = 0.01
if not idprop.has_key('maxscale'): idprop['maxscale'] = 100.0

# create temporary vars for interface
minscl = Draw.Create(idprop['minscale'])
maxscl = Draw.Create(idprop['maxscale'])


# define and draw pupblock
block = []
block.append(("Minimum Scale", minscl, 0.001, 10000.0, "The minimum width scale."))
block.append(("Maximum Scale", maxscl, 0.001, 10000.0, "The maximum width scale."))

retval = Draw.PupBlock("Volume Preserve Constraint", block)

# update id-property values after user changes settings
if (retval):
idprop['minscale']= minscl.val
idprop['maxscale']= maxscl.val

[peengoh]

Wow, Thanks a lot, Im going to take a look and will let you know the results...