1. Bifröst Physics Arman J. Frasier Christopher Newport University Department of Physics, Computer Science, and Engineering Mentor: David Heddle April 22 nd, 2011 Washington Room, David Student Union

2. Bifröst Physics Christopher Newport University Arman J. Frasier Roadmap  What is Bifröst Physics?  The Physics  The Programming  Future Development  Conclusion & Questions

3. Bifröst Physics Christopher Newport University Arman J. Frasier What is Bifröst Physics?  A two dimensional physics simulator designed to facilitate long distance physics education through a local network or the internet.  Developed in Java

4. Bifröst Physics Christopher Newport University Arman J. Frasier Features Physics Simulator  Kinematics  Inelastic Collisions  Mutual gravitational and electric effects  Gravitational and Electric fields  Fluidic Resistance  Trajectory tracing  Velocity vector display  Automatic entity generation  Optimized threading  Alterable time iteration

5. Bifröst Physics Christopher Newport University Arman J. Frasier Features Renderer  Accelerated 2D graphics through AWT  Maximum frame rate of 60 frames per second Networking  Integrated chat functions  Ability to transfer simulation data  Centralized Relay  Low bandwidth usage

6. Bifröst Physics Christopher Newport University Arman J. Frasier Physics  Steps through each entity, calculating the net acceleration affecting that entity.  Uses these accelerations in basic kinematic equations, along with a specified time step, to determine the new velocity and position vectors of each entity.

7. Bifröst Physics Christopher Newport University Arman J. Frasier Collisions  The false positive check helps correct errors from large time steps. Pseudo-code algorithm: if(distance > (radius1 + radius2)) { //no collision (too far away) return; } else { rotate frame so that the collision vector becomes the new x axis } if (not false positive) { //collision do collision calculations } return frame to normal rotation return; An example of a false positive collision

8. Bifröst Physics Christopher Newport University Arman J. Frasier Collision Example Detect collisionFind collision vectorRotate the frame, making the collision vector x’. Find the x-component of each entity’s velocity Use the x-components in these 1D inelastic collision formulas to calculate new x- components. Update the velocity vectors, and then return the frame to its original rotation.

9. Bifröst Physics Christopher Newport University Arman J. Frasier Programming  Simulation Programming  Network Programming

10. Bifröst Physics Christopher Newport University Arman J. Frasier Simulation Programming  Upon initialization, the simulation control thread creates as many worker threads as there are logical processors on the host machine.  These threads are synchronized using a sleep/interrupt schema.

11. Bifröst Physics Christopher Newport University Arman J. Frasier Simulation Threading Taskmaster Simulation Control Worker Threads (One per logical processor) Aggregate Data 1 kHz Simulation Calculations Sleep Proceed Interrupt Action Thread Legend Update Entity Data Play? YesNo

12. Bifröst Physics Christopher Newport University Arman J. Frasier Network Programming  Central host accepts connections from clients  Host sends physics data to clients  Host acts as a chat relay for clients  Low bandwidth usage

13. Bifröst Physics Christopher Newport University Arman J. Frasier Future Development  Networked simulation calculations  Simulation video capture  Further simulation optimization  Extension into 3D  Abstraction of Physics simulation with API

14. Bifröst Physics Christopher Newport University Arman J. Frasier Conclusion  Bifröst Physics can help students understand complex physical concepts through instructor designed experiments, as well as through instructor led networked class sessions.

15. Bifröst Physics Christopher Newport University Arman J. Frasier Questions? Resources  Project Webpage (Includes jar files, user’s guide, change log, and this presentation) http://www.pcs.cnu.edu/~afrasier/bifrost  Contact: arman.frasier.06@cnu.edu