Universe Simulation on GPU

• A multi-million particle gravity simulation.
• The main program is org.davu.app.Space.main
• See each package.html for code details.
• Currently only builds with Windows natives. (see TODOs)
• Currently only works with Intel chipset. (see TODOs)
• davu is short for David Uselmann

Controls

Space.main

• ESC key quit (also window x button)
• W/A/S/D moves forward,left,back,right (i.e. FPS)
• R/F keys (or shift+W/S) moves up,down
• Q/E keys rolls CCW/CC
• Ctrl+3 toggles 3D glasses mode.
• Ctrl+D+up/down arrows adjusts 3D glasses separation.
• Ctrl+A+up/down arrows adjusts particle alpha value.
• Ctrl+T+up/down arrows adjusts time step.
• Left mouse button looks in that direction.
• Right mouse button increase speed much faster.
• Letting go of all controls reduces speed.

There is a 5 second delay before OpenCL is called so there
is time to change location before gravity. Often when creating
new scenarios, the gravity warps the initial state too soon.
It is useful to find different view points to get a feel for
things before they start animating.

opencl.advanced classes

• Click and drag to move the simulation in the window
• Mouse roller or touchpad two-finger scroll to zoom in/out

Purpose

• To make a million (or more) particle engine. Check.
• To learn how to run code on the GPU. Check.
• To learn how to link OpenCL to OpenGL. Check.
• To visualize gravity on a massively parallel scale. Check.
• To demonstrate the power of the the GPU in today's laptops. Check.
• To have fun. Check. Check. Check.

Build Gravity jar

mvn package

Running Space main

java -jar target/gravity.jar
java -jar target/gravity.jar <scenario class name>

Running Other main

java -cp target/gravity.jar org.davu.opencl.advanced.Saturn

Override main in custom gravity.jar

mvn package -Dclass=org.davu.opencl.advanced.Saturn
java -jar target/gravity.jar

Technologies

• LWJGL - Java Gaming Library OpenGL/CL/AL (and others) link to native resources.
• OpenGL - Open Graphic Library to render simulations.
• OpenCL - Open Computing Library to compute Newtonian gravity.
• Java2D - Java AWT window and rendering is used for some demos.
• JOML - Linear algebra math framework.

TODOs

Architecture detecting pom.xml

• The current pom.xml is only configured for Windows natives.
• When I used this OS detecting pom, it pulled down all native jars.
• This cause conflicts where the wrong OS native was bound to the JVM.
• https://github.com/LWJGL/lwjgl3-demos/blob/main/pom.xml
• Looking at the pom and replace the OS native with yours
• <lwjgl.natives>natives-windows</lwjgl.natives>
• then it should work for your machine architecture.

OpenGL GPU Selection

• I could not find a GPU selector for OpenGL. It selects GPU 0.
• I matched the OpenGL GPU for OpenCL.
• See org.davu.app.space.OpenCL.java line 57 for OpenCL GPU assignment.

Maybe change package.html

• Thinking I might rather they be readme.md files for github display.

Maybe add some sound

• The pom has openal jar dependency for when I get around to implementing some sound.

Special Note

• Newtonian gravity is normalizable. The distances and masses are relative magnitude numbers.
• This could be a natural range if Newton's Constant and actual kg, m, sec initial conditions are used.

All Other Scenarios

java -jar target/gravity.jar Explosion3D
java -jar target/gravity.jar Galactic
java -jar target/gravity.jar Galaxies
java -jar target/gravity.jar Galaxies2
java -jar target/gravity.jar Galaxies2a
java -jar target/gravity.jar Galaxies2b
java -jar target/gravity.jar Orbitally
java -jar target/gravity.jar SprialRibbon
java -jar target/gravity.jar Universe2D
java -jar target/gravity.jar Universe3D

All Other main methods

java -cp target/gravity.jar org.davu.opencl.simple.TestInfo
java -cp target/gravity.jar org.davu.opencl.simple.Test1D
java -cp target/gravity.jar org.davu.opencl.simple.Test1Dvector
java -cp target/gravity.jar org.davu.opencl.simple.Test2D
java -cp target/gravity.jar org.davu.opencl.simple.Test2D2D
java -cp target/gravity.jar org.davu.opencl.simple.TestR2D2D

java -cp target/gravity.jar org.davu.opencl.advanced.Explosive
java -cp target/gravity.jar org.davu.opencl.advanced.Explosive2
java -cp target/gravity.jar org.davu.opencl.advanced.Galaxies
java -cp target/gravity.jar org.davu.opencl.advanced.Galaxies2
java -cp target/gravity.jar org.davu.opencl.advanced.GalaxiesDarkMatter
java -cp target/gravity.jar org.davu.opencl.advanced.GalaxiesDarkMatterVar
java -cp target/gravity.jar org.davu.opencl.advanced.GalaxyArms
java -cp target/gravity.jar org.davu.opencl.advanced.Globular3D
java -cp target/gravity.jar org.davu.opencl.advanced.Gravity
java -cp target/gravity.jar org.davu.opencl.advanced.Helix
java -cp target/gravity.jar org.davu.opencl.advanced.Helix2
java -cp target/gravity.jar org.davu.opencl.advanced.Orbitally
java -cp target/gravity.jar org.davu.opencl.advanced.Saturn
java -cp target/gravity.jar org.davu.opencl.advanced.SaturnClose
java -cp target/gravity.jar org.davu.opencl.advanced.SaturnSpiral
java -cp target/gravity.jar org.davu.opencl.advanced.SolarSystem
java -cp target/gravity.jar org.davu.opencl.advanced.SolarSpeedy
java -cp target/gravity.jar org.davu.opencl.advanced.Universe
java -cp target/gravity.jar org.davu.opencl.advanced.Universe2