Blender Script for creating animated motion-trail ribbon

Given an object for which a motion-path has been generated, will create a Beziér-spline ribbon that follows the motion of the object for a given tail length (designated in frames).

# ---------
# Tested in Blender 2.75a and 2.76
# Makes a Bezier-spline motion trail for an object.
# Set the length of the tail in frames via the tail_length variable below.
# To run, select object, generate a motion path for the object (Editor>Motion Paths) across the total desired frame range, and Run Script.
# Warning: this can take a long time to run with long motion paths and long tail sizes
# Once the spline has been generated, extrude and/or add bevel and taper objects to the Geometry settings of the spline.
# Bret Battey / BatHatMedia.com September 2015
# ---------

import bpy
from bpy.props import *
from mathutils import *
from math import *
import time

# ----- FUNCTION DEFINITIONS -----

# Time utils thanks to http://blenderscripting.blogspot.co.uk/search/label/time

def get_last_time():  
    if len(time_list) < 2:  
        return "ERROR: must have two time entries to calculate the difference"  
    return time_list[-1] - time_list[-2]      
  
def mark_time():  
    time_list.append(time.time())      
  
time_list = [] 


##------------------------------------------------------------
#### Curve creation functions
# sets bezierhandles to auto
def setBezierHandles(obj, mode = 'AUTOMATIC'):
    scene = bpy.context.scene
    if obj.type != 'CURVE':
        return
    scene.objects.active = obj
    bpy.ops.object.mode_set(mode='EDIT', toggle=True)
    bpy.ops.curve.select_all(action='SELECT')
    bpy.ops.curve.handle_type_set(type=mode)
    bpy.ops.object.mode_set(mode='OBJECT', toggle=True)


# create new CurveObject 
def createCurve(verts, name):
      
    # create curve
    scene = bpy.context.scene  
    newCurve = bpy.data.curves.new(name, type = 'CURVE') # curvedatablock
    newSpline = newCurve.splines.new(type = 'BEZIER') # spline

    # The new spline already has one point. Add the remaining needed.
    newSpline.bezier_points.add(verts-1)

    # set curveOptions
    newCurve.dimensions = '3D'

    # create object with newCurve
    new_obj = bpy.data.objects.new(name, newCurve) # object
    scene.objects.link(new_obj) # place in active scene
    new_obj.select = True # set as selected
    scene.objects.active = new_obj  # set as active

    # set bezierhandles
    setBezierHandles(new_obj)

    return new_obj

#based on animation_rotobezier.py
def keyframeBezier(Obj, frame):

    Data = Obj.data
    
    for Spline in Data.splines:
        for CV in Spline.bezier_points:
            CV.keyframe_insert(data_path='co', frame = frame)
            CV.keyframe_insert(data_path='handle_left', frame = frame)
            CV.keyframe_insert(data_path='handle_right', frame = frame)
    
# -------------  SCRIPT START

tail_length = 60   # length of the spline in frames
object = bpy.context.object
path = object.motion_path
frame_start = path.frame_start
frame_end = path.frame_end
path_length = path.length

# --- create the Bezier curve
trail = createCurve(tail_length,object.name+" motion_trail")

mark_time() # start measuring elapsed time

# --- key frame the curve at every frame in the motion path

for i in range(tail_length-1,path_length): # motion path index
    print("Point "+str(i))
    for j in range(tail_length): # curve point index 
        trail.data.splines[0].bezier_points[j].co = path.points[(i-tail_length)+j].co # set the coordinates of the motion tail to the corresponding point on the motion path
    # keyframe it
    keyframeBezier(trail, frame_start+i)
    
mark_time()

print('The motion trail keyframing took {: 5g} seconds'.format(get_last_time()))

Blender Script for object-motion measurements

In Blender, given an object that has a motion path, will provide animated empties which indicate the object's velocity, acceleration, magnitude, and accumulated distance moved.

# ---------
# Tested on Blender 2.75a and 2.76
# For a given object, makes an empty, which moves to indicate the velocity (displacement between frames) for each axis of the original object
# and another empty providing magnitude of the movement
# and another empty providing accumulative displacement for each axis, 
# and yet another for acceleration. 
# To run, select object, generate a motion path for the object (Editor>Motion Paths) across the total desired frame range, and Run Script.
# Bret Battey / BatHatMedia.com Dec 2015
# ---------

import bpy
from bpy.props import *
from mathutils import *
from math import *
import time

# ----- FUNCTION DEFINITIONS -----

# Time utils thanks to http://blenderscripting.blogspot.co.uk/search/label/time

def get_last_time():  
    if len(time_list) < 2:  
        return "ERROR: must have two time entries to calculate the difference"  
    return time_list[-1] - time_list[-2]      
  
def mark_time():  
    time_list.append(time.time())      
  
time_list = [] 


# -------------  SCRIPT START

object = bpy.context.object
path = object.motion_path
frame_start = path.frame_start
frame_end = path.frame_end
path_length = path.length
# velocity empty
bpy.ops.object.empty_add(type='PLAIN_AXES', radius=1, view_align=False, location=(0,0,0), layers=object.layers)
velempty = bpy.context.object
velempty.name = object.name + '_velocity'
# vector magnitude 
bpy.ops.object.empty_add(type='PLAIN_AXES', radius=1, view_align=False, location=(0,0,0), layers=object.layers)
magempty = bpy.context.object
magempty.name = object.name + '_magnitude'
# accumulative distance traveled 
bpy.ops.object.empty_add(type='PLAIN_AXES', radius=1, view_align=False, location=(0,0,0), layers=object.layers)
accumempty = bpy.context.object
accumempty.name = object.name + '_accum_distance'
# acceleration 
bpy.ops.object.empty_add(type='PLAIN_AXES', radius=1, view_align=False, location=(0,0,0), layers=object.layers)
accelempty = bpy.context.object
accelempty.name = object.name + '_acceleration'

mark_time() # start measuring elapsed time

for i in range(0,path_length-2): # motion path index
    nextPointCo = path.points[i+1].co # next time point
    thisPointCo = path.points[i].co # this time point
    dif = nextPointCo-thisPointCo # x,y,z distances
    mag = sqrt(dif[0]*dif[0]+dif[1]*dif[1]+dif[2]*dif[2]) # vector magnitude via pythagorean theorem
    velempty.location = dif # set vel empty's location to the velocity vector
    magempty.location[2] = mag # set z position of mag empty's location to the magnitude
    frame = frame_start+i  # get absolute frame number
    velempty.keyframe_insert(data_path='location',frame=frame,index=-1) # set keyframe for velocity. index -1 = set all three axes
    magempty.keyframe_insert(data_path='location',frame=frame,index=2) # set keyframe for velocity. index -1 = set all three axes
    if i == 0:
        accumempty.keyframe_insert(data_path='location',frame=frame,index=-1) # set keyframe. index -1 = set all three axes
        accumdif = accumempty.location # start accumulated distance with a convenient 0,0,0 vector
    else:
        accumdif[0] += abs(dif[0]) # add absolute value of velocity to the accumulative distance
        accumdif[1] += abs(dif[1])
        accumdif[2] += abs(dif[2])
        accumempty.location = accumdif # move empty to this point
        accumempty.keyframe_insert(data_path='location',frame=frame,index=-1) # set keyframe. index -1 = set all three axes
        accelempty.location = dif-lastdif # acceleration = dif between this frame's velocity and the previous frame's
        accelempty.keyframe_insert(data_path='location',frame=frame-1,index=-1) # set keyframe ONE FRAME BACK. index -1 = set all three axes
    lastdif = dif

   
mark_time()

print('The keyframing took {: 5g} seconds'.format(get_last_time()))

Video Preview of My New OptiNelder Plugin

Video preview of my new OptiNelder plugin for Apple Motion, using Nelder-Mead search agents to crawl on an input image.

https://vimeo.com/149694242

Multisample Antialiasing for FxPlugs

I finally implemented OpenGL Multisample Antialiasing in the context of an Apple FxPlug project. Took me a lot of time to figure this one out (why is it so hard to find clear implementation details on MSAA?). I hope I can save someone else the pain:

https://github.com/bbattey/MSAA-for-FxPlugs

Kochanek Bartels Spline Class for Objective-C + OpenGL

A Kochanek Bartels spline is a lovely, flexible means for casting a curve through multiple points, and providing artistically useful control over the character of the curve. It is also known as a TCB spline, because the controls are Tension, Continuity, and Bias. It was originally developed for providing smooth keyframed animation control curves, but it is also useful for general graphics purposes. For one of my Apple Motion FxPlug projects, I developed a Objective C class to render a Kochanek Bartels spline in OpenGL. It includes an additional feature of interpolating colors between the target points.

 

I have placed the code on GitHub. Corrections/improvements welcomed.

And here's a taste of what happens if one sets the parameters outside of the standard -1 to 1 range. Here T = -4.38, C = -1.31, and B = 0.37:

Triptych Unfolding at Synchresis 2015

The 2015 Synchresis Festival will include Triptych Unfolding in screenings in Valencia (Nov 19), Granada (Nov 24), Canarias (Nov 25 & 26), and Madrid (Nov 27). More information can be found here.

Premiere Performances of "The Five"

My new piece, The Five (for vibraphone and responsive audiovisuals), commissioned by percussionist Andrew Spencer, will be premiered by him in his U.S. tour autumn 2015. The first three performances of his tour are October 30 at University of Northern Colorado, November 3 at San Jose State University, and November 6 at Arizona State University.