README.md

LSysInt

A simple L-System parser, interpreter and renderer, written in VB.NET

This is, in fact, a very rough and simple interpreter to render L-system formulas.

The grammar is very similar to that of the more mature project LILiS, with a few distinctions:

• A curve is defined using a name with its body enclosed between curly brackets.
• Parameters names must always end with a colon.
• So far, only eigth parameters are supported:
  • level: indicates the maximum recursion level
  • axiom: indicates the initial conditions
  • rule: indicates one or more rules to be applied to the axiom
  • angle: defines the default angle when none is specified
  • offsetX: defines a rendering origin offset in the horizontal direction
  • offsetY: defines a rendering origin offset in the vertical direction
  • length: defines the default length of a segment when none is specified
  • constant: defines a simple string-based substitution (no function support yet)
• Although LSysInt does not currently support "definitions", most of the time these can be represented through one or more rules.
• These are the currently supported internal functions:
  • F(x): move forward and draw x amount of pixels
  • B(x): move backwards and draw x amount of pixels
  • f(x): move forward x amount of pixels
  • +(x): increase the angle by x amount
  • -(x): decrease the angle by x amount
  • [: save current vector state
  • ]: restore saved vector state
  • %(r, g, b, a): set vector color

Here's a sample code to render the dragon curve up to its 13th iteration:

    Dragon {
        level: 13
        axiom: -(45) f(0.47) * F(0.6) X(0.6)
        rule: X(n) = X(n/Sqrt(2)) +(90) Y(n/Sqrt(2)) F(n/Sqrt(2)) +(90)
        rule: Y(n) = -(90) F(n/Sqrt(2)) X(n/Sqrt(2)) -(90) Y(n/Sqrt(2))
        rule: F(n) = F(n/Sqrt(2))
        rule: *    = * -(45)
    }