BeeVeeH - another BVH Player

• Table of Content
  • Download
  • Introduction
  • Development
    • Requirements
    • Setup
    • Test
    • Run
  • APIs
    • Quickstart
    • Functions
    • Class BVH.BVHNode
    • Class BVH.BVHChannel

Introduction

BeeVeeH is a BVH player written in Python. BeeVeeH uses OpenGL to render and controls including camera, playback and styling are available. Sculpture mode is for making some "motion sculptures" but with a limitation of 20 sculptures in total (you might want to increase it here if you have a powerful graphic card). BeeVeeH is available for all platforms and pre-built binaries could be found at the release page. For Ubuntu users, make sure you install appropriate OpenGL packages (for example, freeGLUT). BeeVeeH haven't been tested on Ubuntu outside VM, and seems to crash on Ubuntu 17.*.

Development

Requirements

• Python 3.x
• pip (>= 9.0.1, due to the bugs in early pip versions, please make sure the version of pip is 9.0.1 or above by pip3 --version)

If you are using macOS, you can skip this. If you are using Ubuntu, please do the following setups.

Ubuntu prerequisites

Install the following packages via apt:

• libwebkitgtk-dev
• libjpeg-dev
• libtiff-dev
• libgtk2.0-dev
• libsdl1.2-dev
• libgstreamer-plugins-base0.10-dev
• freeglut3
• freeglut3-dev
• libnotify-dev
• libsm-dev
• libgtk-3-dev
• libwebkitgtk-3.0-dev

Setup

macOS/Ubuntu

make init

This process will take a long time to finish on Ubuntu. If you want to speed up, you can try make init-accelerated to download my prebuilt pip packages (I have not built them for all platforms).

Windows

pip install -r requirements.txt -t lib

Test

macOS/Ubuntu

make test

Windows

$env:PYTHONPATH=".\lib"
python -m lib.pytest --ignore=lib

This will run the tests including playing a short sample BVH file.

Run

macOS/Ubuntu

make run

Windows

python -m main

This is the launch the main entry of BeeVeeH.

or,

macOS/Ubuntu

make dist

Windows

$env:PYTHONPATH=""
pip install PyInstaller==3.3
PyInstaller BeeVeeH.spec

This will generate the packed BeeVeeH inside the ./dist directory.

APIs

You might find BeeVeeH's classes BVHNode and BVHChannel useful for parsing and world coordinate extraction.

Quickstart

import BeeVeeH.bvh_helper as BVH


file_path = 'tests/bvh_files/0007_Cartwheel001.bvh'
root, frames, frame_time = BVH.load(file_path)
print('number of frame = %d' % len(frames))
# "number of frame = 2111"

root.load_frame(frames[4])
root.apply_transformation()
print(root.str(show_coordinates=True))
# Node(Hips), offset(0.0, 0.0, 0.0)
#     World coordinates: (18.94, 35.04, -9.44)
#     Channels:
#         Channel(Xposition) = 18.9393
#         Channel(Yposition) = 35.0369
#         Channel(Zposition) = -9.444
#         Channel(Xrotation) = 34.5666
#         Channel(Yrotation) = 71.8402
#         Channel(Zrotation) = -35.4585
#     Node(LeftUpLeg), offset(3.31716, 0.0, 0.0)
#         World coordinates: (19.78, 34.91, -12.65)
#         Channels:
#             Channel(Xrotation) = -5.7958
#             Channel(Yrotation) = 9.0163
#             Channel(Zrotation) = -0.8796
#         Node(LeftLeg), offset(0.0, -16.62131, 0.0)
#             World coordinates: (18.36, 18.36, -12.10)
#             Channels:
#                 Channel(Xrotation) = 9.3583
#                 ...

print(root.search_node('Head').str(show_coordinates=True))
# Node(Head), offset(0.0, 6.84636, 0.0)
#     World coordinates: (23.03, 59.50, -10.77)
#     Channels:
#         Channel(Xrotation) = -5.4518
#         Channel(Yrotation) = -2.1447
#         Channel(Zrotation) = -0.3752

node = root.children[1]
print('The world coordinates of JOINT %s at frames[4] is (%.2f, %.2f, %.2f)' \
       % (node.name, node.coordinates[0], 
          node.coordinates[1], node.coordinates[2]))
# The world coordinates of JOINT RightUpLeg at frames[4] is (18.10, 35.16, -6.24)


root.frame_distance(frames[0], frames[0])
# 0.0

root.frame_distance(frames[0], frames[1])
# 7.5706251988920146

root.search_node('Head').weight = 100.0
root.frame_distance(frames[0], frames[1])
# 34.952071657201969

Functions

BVH.loads(string): (BVH.BVHNode, [[float]], float)

BVH.loads() will parse a string (in BVH format) and return the root node, frames and time between two frames. Each frame is one sample of motion data in the form of a float list. The float numbers appear in the order of the channels.

BVH.load(file_path): (BVH.BVHNode, [[float]], float)

BVH.load() will parse a BVH file and return the root node, frames and time between two frames. Refer to BVH.loads for more details.

Class BVH.BVHNode

Properties

name: string

the name of the node.

children: [BVH.BVHNode]

the list of children nodes.

channels: [BVH.BVHChannel]

the list of channels. Accessing channel.value requires calling BVH.BVHNode.load_frame() first.

offsets: [float]

the offsets, in the form of [x, y, z].

coordinates: numpy.ndarray

the world coordinates, with shape=(3, 1). Accessing it requires calling BVH.BVHNode.load_frame() and BVH.BVHNode.apply_transformation() first.

weight: float

the weight for frame distance calculation.

Methods

__init__(self, name, offsets, channel_names, children)

Constructor.

search_node(self, name): BVH.BVHNode

search_node searches node recursively by name, returns None if not found.

load_frame(self, frame_data_array)

load_frame() assigns a frame. It will map the motion data to each channel. You can get the list of "frame_data_array" from BVH.load() or BVH.loads().

apply_transformation(self, parent_tran_matrix=np.identity(4))

apply_transformation() starts the calculation of world coordinates. Call this method on the root BVHNode only (no parameter needed).

str(self, show_coordinates=False): string

str() returns a readable string containing information about the node and its childrens. Before setting show_coordinates=True, make sure call BVH.BVHNode.load_frame() and BVH.BVHNode.apply_transformation() first.

frame_distance(self, frame_a, frame_b): float

frame_distance calculates the Euclidean distances of all joints between two frames, and returns the weighted sum.

Class BVH.BVHChannel

Properties

name: string

the name of the channel.

value: float

the value of the channel, in degree when the channel represents a rotation. Accessing it requires calling BVH.BVHNode.load_frame() first.

Methods

__init__(self, name)

Constructor.

set_value(self, value)

set_value() is the setter for value.

matrix(self): numpy.ndarray

matrix() returns the transformation matrix of the channel.

str(self)

str() returns a readable string containing information about the channel.