Table of Contents

1. Features
2. Installation
3. Example
4. Building From Source

JavaSim

Java simulation framework.

Features

• Easy to extend Simulation class.
  • provides a sort of canvas to draw on.
  • easy animation with repeatedly-called "draw" function.
• Program that reads your extended class can:
  • save generated images.
  • create animations.
  • run at variable rates.
  • run frame-by-frame.
  • view in full screen.

Installation

See the latest releases for downloads.

After running the application for the first time, a folder called JavaSim should appear in your Documents folder. Jar files for JavaSim simulations placed here will appear on the application's main screen. They can then be selected to load the simulation.

Example

The following program is designed to generate an image of a nephroid. Running File → Create Animated Gif with the default settings saves this image:

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Point;

import com.marklalor.javasim.simulation.preset.BlankImageSimulation;

//Last updated with JavaSim 1.3.0
package com.marklalor.simulation;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Point;

import com.marklalor.javasim.simulation.preset.BlankImageSimulation;

//Last updated with JavaSim 1.3.0
public class Nephroid extends BlankImageSimulation
{
    @Override
    public void draw(Graphics2D graphics)
    {
        //Move the origin from the corner to the center.
        graphics.translate(getImage().getWidth()/2, getImage().getHeight()/2);
        
        //Choose a semi-transparent black color.
        graphics.setColor(new Color(0f, 0f, 0f, 0.2f));
        
        //Get a radius that is 90% of the way to the edge of the screen.
        double radius = (Math.min(getImage().getWidth(), getImage().getHeight())/2) * 0.9;
        
        //Generate points on a circle using JavaSim's built-in "n", which automatically increments.
        Point point1 = getPoint(n, radius);
        Point point2 = getPoint(n*3, radius);
        
        //Draw a line between the two points.
        graphics.drawLine(point1.x, point1.y, point2.x, point2.y);
        
        //Stop after frame 360.
        if (n == 360)
            breakpoint();
    }
    
    //Get a point on the radius of a circle.
    private static Point getPoint(double angle, double radius)
    {
        int x = (int)(radius*Math.cos(Math.toRadians(angle)));
        int y = (int)(radius*Math.sin(Math.toRadians(angle)));
        return new Point(x, y);
    }
}

This bare bones program works by overriding draw(Graphics2D permanent, Graphics2D temporary). The differences between Graphics2D permanent and Graphics2D temporary are simple. Things drawn onto permanent persist throughout an animation, whereas objects drawn on to temporary are cleared each frame. This simulation draws one semitransparent black line onto the permanent graphics each frame, connecting each angle to the angle three times it.

See the getting started page for a full introduction on how and what to use.

Building From Source

JavaSim uses Apache Ant for building and Ant Task JarBundler (Tobias Fischer's fork) for packaging for OS X.

Building requires at least Ant and a Java 7 JDK.

Quick build (only runnable jar):

git clone https://github.com/MarkLalor/JavaSim.git
cd JavaSim/build
ant create_jar

This will create JavaSim.jar in the dist directory.

Full build (runnable jar, OSX .app, and .dmg)

Requires JarBundler and osascript (will certainly not build .dmg on Windows because it relies on applescript. JarBundler for .app should work on Windows, though!)

git clone https://github.com/MarkLalor/JavaSim.git
cd JavaSim/build
ant

This will create JavaSim.app, JavaSim-x.y.z.dmg, and JavaSim-x.y.z.jar in the dist directory.