Crate symbios_shape 

Symbios Shape

A Sovereign Derivation Engine for CGA Shape Grammars.

Symbios Shape is a pure-Rust engine for generating procedural geometry using Computer-Generated Architecture (CGA) Shape Grammars, as popularised by Esri CityEngine. It is designed for embedding in game engines (Bevy, Godot) and offline procedural pipelines where reliability and determinism are paramount.

Key Features

• Lightweight: Depends only on glam (math), nom (parsing), rand (stochastic rules), and optionally symbios-genetics — no engine or runtime required.
• CGA-Compatible Operations: Extrude, Split, Comp, Repeat, Taper, Scale, Translate, Rotate, Align, Offset, Roof, Attach, I, Mat.
• 15 Roof Types: Pyramid, Shed, Gable, Hip, Flat, OpenGable, BoxGable, PyramidHip, Butterfly, MShaped, Gambrel, Mansard, Saltbox, Jerkinhead, DutchGable.
• Flexible Split Sizing: Absolute, relative ('), and floating (~) modes.
• Rich Face Profiles: FaceProfile describes each terminal’s cross-section (Rectangle, Taper, Triangle, Trapezoid, Polygon).
• Genetic Evolution: ShapeGenotype wraps the rule table for symbios-genetics algorithms.
• Bevy-Ready Output: ShapeModel containing Terminal nodes with scope, mesh_id, face_profile, and material.

Example

use symbios_shape::{Interpreter, Scope, Vec3, Quat};
use symbios_shape::grammar::parse_ops;

let mut interp = Interpreter::new();

// A simple 3-storey building
interp.add_rule("Lot", parse_ops("Extrude(12) Split(Y) { 3: Ground | ~1: Upper | 2: Roof }").unwrap());
interp.add_rule("Ground", parse_ops(r#"I("GroundFloor")"#).unwrap());
interp.add_rule("Upper",  parse_ops(r#"I("Floor")"#).unwrap());
interp.add_rule("Roof",   parse_ops(r#"Taper(0.8) I("Roof")"#).unwrap());

let footprint = Scope::new(Vec3::ZERO, Quat::IDENTITY, Vec3::new(10.0, 0.0, 10.0));
let model = interp.derive(footprint, "Lot").unwrap();

assert_eq!(model.len(), 3);
assert_eq!(model.terminals[0].mesh_id, "GroundFloor");
assert_eq!(model.terminals[2].mesh_id, "Roof");
assert!(matches!(model.terminals[2].face_profile, symbios_shape::FaceProfile::Taper(t) if (t - 0.8).abs() < 1e-9));

Re-exports

pub use error::ShapeError;

pub use interpreter::Interpreter;

pub use model::FaceProfile;

pub use model::ShapeModel;

pub use model::Terminal;

pub use ops::AttachCase;

pub use ops::AttachSelector;

pub use ops::Axis;

pub use ops::CompTarget;

pub use ops::FaceSelector;

pub use ops::OffsetCase;

pub use ops::OffsetSelector;

pub use ops::RoofCase;

pub use ops::RoofConfig;

pub use ops::RoofFaceSelector;

pub use ops::RoofType;

pub use ops::ShapeOp;

pub use ops::SplitSize;

pub use ops::SplitSlot;

pub use scope::Scope;

Modules

error

genetics

Genetic evolution wrapper for CGA Shape Grammar interpreters.

grammar

interpreter

model

ops

scope

Structs

Quat

A double-precision unit quaternion. Re-exported from glam. A quaternion representing an orientation.

Vec3

A 3-component double-precision vector. Re-exported from glam. A 3-dimensional vector.