marbles

README

Marbles App

Graph equations and run marbles on them. Based on desmos.com. Uses goki/gi for graphics, and Knetic/govaluate for evaluating equations.

Install

To install run

$ go install github.com/kplat1/marbles@latest

Once you have done this you should be able to launch marbles by just doing

$ marbles

If the install does not work, check the GoKi Install Page and make sure you have installed the prerequisites. If the widgets example doesn't work, then marbles won't work.

If there is a new version of marbles released, just run this command again to update:

$ go install github.com/kplat1/marbles@latest

Features

• For lines
  • You can set a condition that has to be true for the line to be graphed (GraphIf). For example you could do x>3 or you could do y<5. Operators such as || and && are supported.
  • You can set bounciness for a line. If it is 1, the marble will not gain or lose speed after hitting the line. If bounciness is less than 1, marbles will lose speed when they hit the line. If it is greater than one, marbles will gain speed.
  • You can set the color marbles that hit the line will change to (LineColors.ColorSwitch) - none means the marbles stay the same color.
  • You can also set the color for lines (LineColors.Color).
• For the whole graph
  • You can set the amount of marbles that spawn (NMarbles)
  • You can set the starting position of the marbles (MarbleStartX, MarbleStartY). Note: this can be an expression including parameters. For both you can use the parameter n, which is the index of the marble who's position is being set (So if it's the third marble, n will be 2). For MarbleStartY you can also use the parameter x, which is the x value of the marble as calculated by MarbleStartX. The default for MarbleStartX is '0(rand(1)-0.5)'. This expression sets the marbles to spawn randomly in a region of width 0 (a straight line). If you change 0 to 5, this region will be 5 wide. For MarbleStartY, the default is '10-2n/nmarbles()', which makes the marbles spawn with each one just above the other.
  • You can set the starting velocity of the marbles (StartVelX/StartVelY). Note: this can be an expression including parameters like x and y.
  • You can set the update rate of the marbles (UpdtRate). Note: this can be an expression including parameters like x and a.
  • You can set the gravity of the marbles (YForce). Note: this can be an expression including parameters like x and a.
  • You can set the wind of the marbles (XForce). Note: this can be an expression including parameters like x and a.
  • You can set the amount the variable t increases every step (TimeStep). Note: this can be an expression including parameters like x and a.
  • You can set the center point of the graph (CenterX and CenterY). Note: this can be an expression including parameters like a and t.
  • TrackingSettings - See the section on tracking settings
• Controls
  • Graph graphs all of the lines and resets the marbles to their starting positions
  • Run runs the marbles for NSteps
  • Stop stops the marbles
  • Step runs the marbles for one step
• Settings
  • You can customize the default line that will be added if a line is empty
  • You can customize the default graph parameters
  • You can change the size and color of marbles, default means the marbles will spawn in different random colors. Note that collision is not affected by changing the size of the marbles, so it is not recommended to change the size too much or things will look weird
  • You can change the color of most things in the app
• Tracking Settings
  • Tracking allows you to view the paths of marbles.
  • TrackByDefault: Whether all marbles start with tracking on. You can go between individual marbles with the next marble button and then click track to toggle the tracking settings for that marble.
  • NTrackingFrames: How many frames to track marble activity and graph it. There will only be tracking lines for this many frames for each marble on the screen.
  • Accuracy: Accuracy is how many times per 100 frames the tracking lines are updated. Accuracy can be any integer from 1 to 100. The higher accuracy the more accurate and less choppy the tracking lines will be. However higher accuracy will worsen performance.
  • Line Color: The color of the tracking lines. If set to white, the color of the tracking lines will be the color of the marble creating the tracking line.
• Saving and Opening graphs
  • You can save your graph to a json file and open it later. You can also open the last saved graph of the last session of marbles.
  • You can save the graph to a png file, or copy it to your clipboard.
  • You can upload a graph you make by clicking upload graph and giving it a name. Anyone else can download that graph if they want to. Your graph will be automatically deleted after a week.
  • You can view graphs other people have uploaded by clicking download graph and choosing a graph. It will open that graph and you can run it and make any changes to it you want. You can save the graph to your device and do anything you want with it.
• Important note for color and color switch: If you set color switch to white (RGBA(255, 255, 255, 255)), then the marbles will not change color upon hitting that line. It is strongly recommended that you have white as your default line color switch value in settings. Also, if you would like lines to automatically be in random different colors, keep the default color value for lines in settings at white. If you set it to something other than white, all new lines you make will be just that color by default.

How to write equations

• Equations are written in the form y = ... for now, so no circles.
• There are 4 variables you can use: x, h, t, and a. x is the x value, h is the amount of times the line has been hit since the marbles were ran, t is the time passed since running the marbles (incremented by TimeStep), and a is a number that goes back and forth between -10 and 10 (defined as 10*sin(t)).
• There are three constants you can use: pi, e, and inf.
• Note: any value (including variables) can be used for the functions and operations below
• The following operations are supported:
  • +, -, *, /
  • v1^v2 for exponents
  • v1%v2 for the modulo operation
• View the supported functions here

Known Bugs

• Marbles will go sometimes through lines, especially if the lines are moving (using t or a)

Images

The app:

The app can support a wide variety of functions: