I seem to forget the basics of working with matrices in C4D immediately after I use them. Here are some resources and helper functions:
Maxon's
How to Use Matrices
C4D Python SDK Matrix Reference
Some PSR helper functions written by Maxon with additions for point manipulation by me
############## HIERARCHY HELPERS ######################
def GetGlobalPosition(obj):
"""
Returns the global position of obj
"""
return obj.GetMg().off
def GetGlobalRotation(obj):
"""
Returns the global rotation of obj
"""
return utils.MatrixToHPB(obj.GetMg())
def GetGlobalScale(obj):
"""
Returns the global scale of obj
"""
m = obj.GetMg()
return c4d.Vector( m.v1.GetLength(),
m.v2.GetLength(),
m.v3.GetLength())
def SetGlobalPosition(obj, pos):
"""
Sets the global position of obj to pos
"""
m = obj.GetMg()
m.off = pos
obj.SetMg(m)
def SetGlobalRotation(obj, rot):
"""
Sets the global rotation of obj to rot
Please remember, CINEMA 4D handles rotation in radians.
Example for H=10, P=20, B=30:
import c4d
from c4d import utils
#...
hpb = c4d.Vector(utils.Rad(10), utils.Rad(20), utils.Rad(30))
SetGlobalRotation(obj, hpb) #object's rotation is 10, 20, 30
"""
m = obj.GetMg()
pos = m.off
scale = c4d.Vector( m.v1.GetLength(),
m.v2.GetLength(),
m.v3.GetLength())
m = utils.HPBToMatrix(rot)
m.off = pos
m.v1 = m.v1.GetNormalized() * scale.x
m.v2 = m.v2.GetNormalized() * scale.y
m.v3 = m.v3.GetNormalized() * scale.z
obj.SetMg(m)
def SetGlobalScale(obj, scale):
"""
Sets the global scale of obj to scale
"""
m = obj.GetMg()
m.v1 = m.v1.GetNormalized() * scale.x
m.v2 = m.v2.GetNormalized() * scale.y
m.v3 = m.v3.GetNormalized() * scale.z
obj.SetMg(m)
def LocalToGlobal(obj, local_pos):
"""
Returns a point in local coordinate in global space.
"""
obj_mg = obj.GetMg()
return obj_mg * local_pos
def GlobalToLocal(obj, global_pos):
"""
Returns a point in global coordinate in local space.
"""
obj_mg = obj.GetMg()
return ~obj_mg * global_pos
def SetPointGlobal(point_object, point_index, global_pos):
"""
Sets the global position of point_object's point to global_pos
"""
p_local_pos = GlobalToLocal(point_object, global_pos)
#Set Point
point_object.SetPoint(point_index, p_local_pos)
#Tell C4D the spline has changed.
point_object.Message(c4d.MSG_UPDATE)
#Move this line to the end of your loop if you're call this command a lot.
def SetPointGlobalVirtual(point_object, parent, point_index, global_pos):
"""
Sets the global position of a virtual point_object's point to global_pos
Most useful when setting the points of a spline created in a Python Generator
"""
p_local_pos = GlobalToLocal(parent, global_pos)
#Set Point
point_object.SetPoint(point_index, p_local_pos)
#Tell C4D the spline has changed.
point_object.Message(c4d.MSG_UPDATE) #Move this line to the end of your loop if you're call this command a lot.
def GetPointGlobal(point_object, point_index):
"""
Return the position of a point in Global Space
"""
ppos = point_object.GetPoint(point_index) #Get the point in local coords
return LocalToGlobal(point_object, ppos) #Return the point in global space
#######################################################
