Description
1. Overview
The purpose of this assignment is to introduce you to OpenGL animation for hierarchical modeling and collision
detection. You will program a 3-D vivarium: a simulated 3-D world of polyhedral creatures moving around.
Basic Requirements
1. Predator/Prey Models: To build your vivarium, you will first need to construct two different creatures using
polyhedral (solid) parts. Implement your code as we did at “TODO 1” in the ModelLinkage file.
○ For the basic parts of your creatures, feel free to use routines provided with the previous
assignment. You are also free to create your own basic parts, but they must be polyhedral (solid).
○ The creatures you design should have moving linkages of the basic parts: legs, arms, wings,
antennae, fins, tentacles, etc.
○ Model requirements:
■ Predator: At least one (1) creature. Should have at least two moving parts in addition to the
main body
■ Prey: At least two (2) creatures. The two prey can be instances of the same design. Should
have at least one moving part.
■ The predator and prey should have distinguishable different colors. You are welcome to
reuse your PA2 creature in this assignment.
■ All models should have a distinguishable head/front from the tail/rear side.
○ Vivarium requirements:
■ A test scene with only one (1) predator and one (1) prey, bind to key “T/t”
■ Default scene with at least one (1) predator and two (2) prey, reset after pressing key “R/r”
2. Model animation: Use transforms to control the motion of each creature and its parts. Implement your
code at “TODO 2,” following the example of the animationUpdate method in ModelLinkage.py.
○ Set reasonable joints limit for your creature
○ The creature’s limbs should move back and forth in a periodic manner as it explores the vivarium.
For example, a bird would continuously flap its wings.
3. Collision Detection & Reaction: Creatures in the vivarium should react to the positions of other creatures
and move accordingly. Implement your code at “TODO 3” in the stepForward method of the ModelLinkage
file.
○ Your creature should always stay within the fixed-size 3D “tank”. You should do collision detection
between the creatures and tank walls. When creatures hit the tank walls, they should turn and
change direction to stay within the tank.
■ Using bounding box or bounding sphere for collision detection between creature and wall
■ After collision, the outgoing direction should be a proper reflection
○ Your creatures should have a prey/predator relationship. For example, you could have a bug being
chased by a spider, or a fish eluding a shark. This means your creature should react to the
presence of other creatures in the tank.
■ Use potential functions to change each creature’s direction based on other creatures’
locations, their inter-creature distances, and their current configuration.
■ You should detect collisions between creatures.
1. Predator-prey collision: The prey should disappear (get eaten) from the tank.
2. Collision between the same species: They should bounce apart from each other.
You can use a reflection vector about a plane to decide the after-collision direction.
■ You are welcome to use bounding spheres for collision detection.
■ We recommend that you modularize shared functions (making two creatures bounce off
each other, detecting if a creature is within the tank walls, etc.) within the
EnvironmentObject class. This will allow all creatures to inherit the same basic methods,
which will form the backbone of each stepForward routine.
○ Your creatures should be able to move in 3 dimensions, not only on a plane.
4. Creature orientation: Creatures should face in the direction they are moving. For instance, a fish should
be facing the direction in which it swims. Remember that we require your creatures to be movable in 3
dimensions, so they should be able to face any direction in 3D space. Implement your code at “TODO 4”
in the rotateDirection method of EnvironmentObject.py.
5. (CS680 Required, Extra credit for CS480 students) Feed your creatures with food: Add chunks of
food to the vivarium which can be eaten by your creatures. Implement your code at “BONUS 5(TODO 5)”
in the Vivarium file.
○ When ‘f’ is pressed, have a food particle be generated at random within the vivarium.
○ Be sure to draw the food on the screen with an additional model. It should drop slowly to the
bottom of the vivarium and remain there within the tank until eaten.
○ The food should disappear once it has been eaten. Food is eaten by the first creature that touches
it.
Extra Credit (Maximum 10 points)
6. Flocking behavior: Add at least 5 creatures to the vivarium and make it possible for creatures to engage
in group behaviors, for instance flocking together. This can be achieved by implementing the Boids
animation algorithms of Craig Reynolds. Implement your code at “BONUS 6” in the ModelLinakge file.
Your in-person demo should make the flocking behavior very obvious/easy to see in order to
receive credit.
7. Creature stays upright: Use an extra corrective factor to ensure the creature always remains upright. The
model also needs to have a distinctive upper and lower body, so the behavior is obvious enough for
grading.
Programming Style
For any modified or newly added source file, you should include a brief description of how this file was changed.
Add this information to the file heading along with your name and ID. Your code should be readable with sufficient
comments. You should use consistent variable naming and keep reasonable indentation.
README
With each assignment, please upload a README text or markdown file with the following information:
● your name
● any collaborators that you spoke to
● the class
● the assignment number
● a brief summary of the code and implementations you have written for the assignment
For the last point, you should outline the method you used to solve the problem, describe the variables and
data-structures used in the program, any error conditions which might be encountered in the solution, and how
these error conditions are handled by the solution.
If these details are described in the comments above the relevant functions or files, you may be brief here. You
may call this file “READMEStudent” or something analogous to differentiate it from the README in the skeleton
code.
Please include a mention of any resources that you consulted while completing your assignment.
2 Resources
2.1 Starter code
A Python program skeleton, which includes basic classes, methods, and main pipeline, is provided for you. You
are expected to complete the parts marked with TODO. There are comments in the skeleton code that will help
guide you in writing your own subroutines.
The source files can be downloaded under the “Resources” tab on Piazza as “PA3 starter code.”
2.2 Environment setup
Installing the appropriate programming environment should be covered in a lab session. For more step-by-step
instructions, please refer to “Environment Setup” under the Piazza “Resources” tab.
2.3 User Interface
R/r: Reset everything in the Vivarium (including put eaten creatures back)
T/t: Test scene with only one predator and one pray
F/f: Add food
(Optional) You can set your key bindings to add creatures to the Vivarium.
2.4 Video Demo
A video demo has been prepared to help you better understand your tasks and speed up your debugging
process:
PA3 Demo.m4v
3. Submission: Due Tuesday 11/4, 11:59 PM EST(midnight)
3.1 Files to Submit
Your program’s source files are to be submitted electronically on Gradescope. The code you submit should
conform to the program assignment guidelines.
3.2 Demo
Part of your grade for this programming assignment will be based on your giving a short demo (10 minutes) during
the CS480/680 scheduled labs following the assignment due date. You will be expected to talk about how your
program works, and will be asked related comprehension questions.
4. Grading
Students can receive at maximum 10 points of extra credit.
Requirements CS480 CS680
Produce predator & prey with moving parts 25 25
Creatures face in direction they are moving 25 25
Collision detection and creatures react to each other 20 20
Creatures stay inside the tank as described above 20 20
Food can be added, creatures find and eat the food as described
above
5 (extra) 10
Group behavior modeling 10 (extra) 10 (extra)
Creature stays upright 2.5 (extra) 2.5 (extra)
Programming Style 10 10
5. Code Distribution Policy
You acknowledge this code is only for the course learning purpose. You should never distribute any part of this
assignment, especially the completed version, to any publicly accessible website or open repository without our
permission. Keeping the code in your local computer or private repository is allowed. You should never share, sell,
gift, or copy the code in any format with any other person without our permission.
