Enum JSONDrawRules

Source

pub enum JSONDrawRules {
    Simple {
        replacement: HashMap<char, String>,
        angle_numerator: isize,
        angle_denominator: usize,
        start: String,
    },
    Advanced {
        replacement: HashMap<char, String>,
        draw_step_sizes: HashMap<char, f64>,
        move_step_sizes: HashMap<char, f64>,
        angle_numerator: isize,
        angle_denominator: usize,
        start: String,
    },
    Full {
        replacement: HashMap<char, String>,
        assignment: HashMap<char, JSONDrawAction>,
        start: String,
    },
}

Expand description

Represents user input from JSON of the L-System rules, for conversion into DrawRules.

Variants§

§

Simple

Most basic specification syntax for rules.

The following commands are defined:

+: rotate clockwise by angle
-: rotate counterclockwise by angle
[: push current location/angle pair onto stack 0
]: pop location/angle pair off of stack 0

The angle is specified as PI * angle_numerator / angle_denominator.

Every other character represents drawing forward a distance of 1.0.

§Example

use std::collections::HashMap;
use std::f64::consts::PI;

use l_system_fractals::parse_files::{JSONDrawAction, JSONDrawRules};
use l_system_fractals::rules::{
    DrawAction,
    DrawRules,
    InitializedDrawRules,
    RuleAssignment,
    RewriteRules
};
use l_system_fractals::num_validity::AlmostEq;

// Koch snowflake
// from Benoit B. Mandelbrot (1983), _The Fractal Geometry of Nautre (Updated and
// Agumented)_, New York: W.H. Freeman and Company, p. 42

let json_string = r#"{
    "type": "Simple",
    "replacement": {"A": "A+A--A+A"},
    "angle_numerator": 1,
    "angle_denominator": 3,
    "start": "+A--A--A"
}"#;

let json_dr: JSONDrawRules = serde_json::from_str(json_string).unwrap();
let dr1: InitializedDrawRules = json_dr.try_into().unwrap();

let rwr = RewriteRules(HashMap::from([('A', "A+A--A+A".into())]));
let assignment = RuleAssignment(
    HashMap::from([
        ('A', DrawAction::DrawForward(1.0)),
        ('+', DrawAction::RotateCW(PI/3.0)),
        ('-', DrawAction::RotateCW(-PI/3.0)),
        ('[', DrawAction::Push(0)),
        (']', DrawAction::Pop(0))
    ])
);

let dr2 = InitializedDrawRules {
    draw_rules: DrawRules {
        rewrite_rules: rwr,
        assignment,
    },
    start: "+A--A--A".into()
};
assert!(dr1.almost_eq(&dr2, 0.001));

Fields

§replacement: HashMap<char, String>

Describes the replacement used in each iteration step.

§angle_numerator: isize

Numerator of fraction of π to rotate.

§angle_denominator: usize

Denominator of fraction of π to rotate.

§start: String

Initial string.

§

Advanced

A more advanced specification syntax for rules that provides more flexibility.

The following commands are defined:

+: rotate clockwise by angle
-: rotate counterclockwise by angle
[: push current location/angle pair onto stack 0
]: pop location/angle pair off of stack 0

The angle is specified as PI * angle_numerator / angle_denominator.

Other characters are mapped to drawing or moving forward based on the fields draw_step_sizes and move_step_sizes.

Any other character is mapped to Null.

§Example

use std::collections::HashMap;
use std::f64::consts::PI;

use l_system_fractals::parse_files::{JSONDrawAction, JSONDrawRules};
use l_system_fractals::rules::{
    DrawAction,
    DrawRules,
    InitializedDrawRules,
    RuleAssignment,
    RewriteRules
};
use l_system_fractals::num_validity::AlmostEq;

// Islands
// from Benoit B. Mandelbrot (1983), _The Fractal Geometry of Nautre (Updated and
// Agumented)_, New York: W.H. Freeman and Company, p. 121

let json_string = r#"{
    "type": "Advanced",
    "replacement": { "A": "A+BA-AA-A-AA+B+AA-BA+AA+A+AA-B-AAA", "B": "BBBBBB" },
    "draw_step_sizes": { "A": 1.0 },
    "move_step_sizes": { "B": 1.0 },
    "angle_numerator": 1,
    "angle_denominator": 2,
    "start": "A-A-A-A-"
}"#;

let json_dr: JSONDrawRules = serde_json::from_str(json_string).unwrap();
let dr1: InitializedDrawRules = json_dr.try_into().unwrap();

let rwr = RewriteRules(HashMap::from([
    ('A', "A+BA-AA-A-AA+B+AA-BA+AA+A+AA-B-AAA".into()),
    ('B', "BBBBBB".into())
]));
let assignment = RuleAssignment(
    HashMap::from([
        ('A', DrawAction::DrawForward(1.0)),
        ('B', DrawAction::MoveForward(1.0)),
        ('+', DrawAction::RotateCW(PI/2.0)),
        ('-', DrawAction::RotateCW(-PI/2.0)),
        ('[', DrawAction::Push(0)),
        (']', DrawAction::Pop(0))
    ])
);

let dr2 = InitializedDrawRules {
    draw_rules: DrawRules {
        rewrite_rules: rwr,
        assignment
    },
    start: "A-A-A-A-".into()
};

assert!(dr1.almost_eq(&dr2, 0.001));

Fields

§replacement: HashMap<char, String>

Describes the replacement used in each iteration step.

§draw_step_sizes: HashMap<char, f64>

Used to define which characters will represent drawing forward (and how much).

§move_step_sizes: HashMap<char, f64>

Used to define which characters will represent moving forward (and how much).

§angle_numerator: isize

Numerator of fraction of π to rotate.

§angle_denominator: usize

Denominator of fraction of π to rotate.

§start: String

Initial string.

§

Full

A specification syntax that allows for complete flexibility.

§Example

use std::collections::HashMap;
use std::f64::consts::PI;

use l_system_fractals::parse_files::{JSONDrawAction, JSONDrawRules};
use l_system_fractals::rules::{
    DrawAction,
    DrawRules,
    InitializedDrawRules,
    RuleAssignment,
    RewriteRules
};
use l_system_fractals::num_validity::AlmostEq;

let json_string = r#"{
    "type": "Full",
    "replacement": {
      "A": "A[A{B<AX",
      "B": "BBBB",
      "X": "}+A{>+A<]+A["
    },
    "assignment": {
      "A": { "type": "DrawForward", "dist": 1.0 },
      "B": { "type": "MoveForward", "dist": 1.0 },
      "X": { "type": "Null" },
      "[": { "type": "Push", "stack": 0 },
      "{": { "type": "Push", "stack": 1 },
      "<": { "type": "Push", "stack": 2 },
      "]": { "type": "Pop", "stack": 0 },
      "}": { "type": "Pop", "stack": 1 },
      ">": { "type": "Pop", "stack": 2 },
      "+": { "type": "RotateCW", "numerator": 2, "denominator": 9 }
    },
    "start": "+A+A+A+A+A+A+A+A+A"
}"#;

let json_dr: JSONDrawRules = serde_json::from_str(json_string).unwrap();
let dr1: InitializedDrawRules = json_dr.try_into().unwrap();

let rwr = RewriteRules(HashMap::from([
      ('A', "A[A{B<AX".into()),
      ('B', "BBBB".into()),
      ('X', "}+A{>+A<]+A[".into())
]));
let assignment = RuleAssignment(
    HashMap::from([
        ('A', DrawAction::DrawForward(1.0)),
        ('B', DrawAction::MoveForward(1.0)),
        ('X', DrawAction::Null),
        ('+', DrawAction::RotateCW(2.0 * PI/9.0)),
        ('[', DrawAction::Push(0)),
        ('{', DrawAction::Push(1)),
        ('<', DrawAction::Push(2)),
        (']', DrawAction::Pop(0)),
        ('}', DrawAction::Pop(1)),
        ('>', DrawAction::Pop(2)),
    ])
);

let dr2 = InitializedDrawRules {
    draw_rules: DrawRules {
        rewrite_rules: rwr,
        assignment
    },
    start: "+A+A+A+A+A+A+A+A+A".into()
};
assert!(dr1.almost_eq(&dr2, 0.001));