Assignment 2: Inverse Kinematics

CMPT466-985 Computer Animation
Programming Assignment 2: Inverse Kinematics (20 points)

In this assignment, you are going to implement Inverse Kinematics for the skeleton’s right
arm using two methods: 1) CCD method; 2) Jacobian method. The default coding
environment is Visual Studio 2017 Community (workload: Desktop development with C++).
Please ensure that your submission is runnable on the desktops with VS2017 (x64
compiler) and Windows 10 installed in ABS9840.
Folder Structure
The template is given as CMPT466-985 Program Assignment 2.zip and a demo is given
with the zip file. You can firstly play with the exe file inside the ResultDemo folder. Visual
Studio 2017 solution file path is build/CMPT466-985 Program Assignment 2.sln.
The source code files are structured as follows:
1) main.cpp: main workflow and OpenGL functions.
2) Skeleton.h/cpp: load/store skeleton and motion data.
3) ForwardKinematics.h/cpp: calculate each joint’s global position and orientation
given skeleton and motion data. The Joint class is also located here. Check more details
in source code
4) InverseKinematics.h/cpp: calculate each joint’s local quaternions with given a given
target object. This is the only file you need to change to complete this
assignment.
5) Vectors.h: vector manipulation functions (e.g., dot product). Feel free to use them.
6) Eigen library environment has been setup for building Jacobian matrix, check more
details on Eigen C++ library’s official web: Link.
How to Control
1) You can switch between CCD mode and
Jocobian mode by pressing c and j,
respectively.
2) You can rotate your camera around the
character by pressing n and m.
3) You can change the target’s position by
presing number keys：
a. 1 and 2 for moving left / right along X axis;
b. 3 and 4 for moving up / down along Y axis;
c. 5 and 6 for moving in / out along Z axis.
4) You can reset the skeleton to T-pose and
target to the position of the right hand in T-pose by presing r.
2
Project Structure
The main function in main.cpp contains the workflow. We have completed the code for
displaying an initial T-Pose skeleton with a given target location (The red sphere on the
character’s right hand). The global x,y and z axes’ directions are also given as three
perpendicular lines (colored with red, green and blue) in front of the skeleton. You only need
to complete the following two functions:
1) void InverseKinematics::CCDMode()
2) void InverseKinematics::JacobianMode()
IK Workflow
The Inverse Kinematics workflow is implemented in void InverseKinematics::IK().
Each time the target’s position is changed by pressing a number key, void
InverseKinematics::IK() would be called. According to current selected mode,
CCDMode() or JacobianMode() is executed for a maximum of iterNum times (initialized to
300). When the distance to target is smaller than threshold (initialized to 0.5f), the
iterative IK is considered converged and will stop.
3
Grading
There are two functions need to be completed within InverseKinematics.cpp as follows.
The CCDMode() and JacobianMode() functions:
What you have:
1) endEffector is initialized to R_Wrist_End joint;
2) base joint is initialized to RightShoulder joint;
3) target is initialized to the target location.
Coding Part 1): 10 /20 points
You need to calculate all the global quaternions of the joints on the
right arm (from RightHand to RightShoulder) to reach the current
target using CCD.
Coding Part 2): 10 /20 points
You need to calculate all the global quaternions of the joints on the
right arm (from RightHand to RightShoulder) to reach the current
target using Jacobian-based approach.
4
Submission
Please submit the InverseKinematics.cpp file. Please include your student number and
your name at the top of the source file in the comment section. Please make sure the code is
runnable in VS2017 community under Windows 10 environment before you submit it.
TA will test your code on the desktops in ASB9840 with VS2017.
Note:
If you meet with following error:
Error MSB8036 The Windows SDK version 10.0.16299.0 was not found.
Go to Project-Property Open the window, change
Configuration_Properties-General-Windows SDK Version to change the SDK
version to your VS2017 SDK version.