Page MenuHome
Files F7604

trackto_notwist.py
Public
Actions

trackto_notwist.py
View Options

#BPYCONSTRAINT
'''
This is an alternative TrackTo constraint that may be better
in some situations than the built-in TrackTo.
It attempts to minimize the twisting of the object relative
to its starting position while it tracks the target.
'''
import Blender
from Blender import Draw
from Blender import Mathutils
from math import *
'''
This variable specifies the number of targets
that this constraint can use
'''
NUM_TARGETS = 1
'''
This function is called to evaluate the constraint
obmatrix: (Matrix) copy of owner's 'ownerspace' matrix
targetmatrices: (List) list of copies of the 'targetspace' matrices of the targets (where applicable)
idprop: (IDProperties) wrapped data referring to this
constraint instance's idproperties
'''
def doConstraint(obmatrix, targetmatrices, idprop):
# Get user-settable parameters
if not idprop.has_key('axis'):
idprop['axis'] = 2
axis = idprop['axis']
# Find the vector that the chosen axis is currently pointing in
if axis == 1: #X
obvec = Mathutils.Vector(1,0,0)
elif axis == 2: #Y
obvec = Mathutils.Vector(0,1,0)
elif axis == 3: #Z
obvec = Mathutils.Vector(0,0,1)
elif axis == 4: #-X
obvec = Mathutils.Vector(-1,0,0)
elif axis == 5: #-Y
obvec = Mathutils.Vector(0,-1,0)
elif axis == 6: #-Z
obvec = Mathutils.Vector(0,0,-1)
obvec = Mathutils.VecMultMat(obvec, obmatrix.rotationPart())
obvec.normalize()
# Find the vector pointing to the target from the object
tarvec = targetmatrices[0].translationPart() - obmatrix.translationPart()
tarvec.normalize()
# Create a rotation matrix representing the shortest
# possible rotation between the two aforementioned vectors
rotaxis = Mathutils.CrossVecs( obvec, tarvec )
rotangle = acos( max(-1.0, min(1.0, Mathutils.DotVecs( obvec, tarvec ))) ) * (180/pi)
rotmat = Mathutils.RotationMatrix(rotangle, 3, "r", rotaxis)
# Apply the rotation to the object
outputmatrix = obmatrix * rotmat.resize4x4()
outputmatrix[3][0] = obmatrix[3][0]
outputmatrix[3][1] = obmatrix[3][1]
outputmatrix[3][2] = obmatrix[3][2]
# Return the new matrix.
return outputmatrix
'''
User-settings menu.
'''
def getSettings(idprop):
# Define user-settable parameters.
if not idprop.has_key('axis'):
idprop['axis'] = 2
# define and draw pupblock
retval = Draw.PupMenu( "Tracking Axis%t | X%x1 | Y%x2 | Z%x3 | %l | -X%x4 | -Y%x5 | -Z%x6" )
# update id-property values after user changes settings
if retval > 0:
idprop['axis']= retval

File Metadata

Mime Type
text/x-python
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
31/3f/1166ddae09cd7bd79f29eb835758

Event Timeline