CS 488: Lab 3 – Rotating Tetrahedron

Welcome to lab, which is a place where you and your peers complete exercises designed to help you learn the ideas discussed in the preceding lectures. It is intended to be a time where you encounter holes in your understanding and talk out loud with your peers and instructor.

Your instructor will bounce around between breakout rooms to check in with you. However, you are encouraged to request assistance if you find your progress blocked.

Designate one of your group to be the host. This individual will be responsible for setting up a Live Share session in Visual Studio Code and submitting your work. No team member should dominate or be expected to carry the group. All members should be writing code and contributing ideas.


Host, follow these steps:

  1. Open Visual Studio Code.
  2. Click File / Open Folder, create a new folder, and open it.
  3. With the Live Share extension installed, select View / Command Palette, and choose Live Share: Start Collaborative Session.
  4. Copy the invitation link to your chat.

Non-hosts, join the session.


Your task in this lab is to implement transformations via matrices. Follow these steps to complete this lab:

  • Render a tetrahedron using indexed geometry. Situate the tetrahedron in model space around the origin. Extend it to fill a wider range than [-1, 1]. Give each vertex a different color.
  • Use an orthographic projection that reveals the entire tetrahedron and whose aspect ratio matches the viewport.
  • Enable the depth test and back-face culling.
  • Add a keydown listener that rotates the tetrahedron some small number of degrees around the current x-axis when Up or Down are pressed and around the current y-axis when Left or Right are pressed. Consult the event parameter’s key property to determine which key was pressed. Apply the new transformation after any existing transformation by concatenating it through matrix multiplication, as in this pseudocode:
    modelToWorld = newRotation * modelToWorld
    By putting the new matrix as the left operand, it will be applied last.
  • Submit your index.js on Crowdsource. Enter the eIDs for your team members. If you need to make changes after you’ve already submitted, just reload the page and resubmit. If you haven’t finished by the end of the scheduled lab time, you are free to continue working. However, the submission must be made before the end of the day to receive credit.


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