openusd 0.6.0

//! Scene description foundations.
//!
//! This module contains common data types used by parsers.
//! Roughly this correspond to C++ SDF module <https://openusd.org/dev/api/sdf_page_front.html>

use std::{collections::HashMap, fmt::Debug};

use anyhow::Result;
use bytemuck::{Pod, Zeroable};
use strum::FromRepr;

use crate::tf::Token;

mod asset_path;
mod change;
mod copy;
mod data;
pub mod expr;
mod file_format;
mod layer;
pub(crate) mod layer_registry;
mod ordering;
mod path;
mod path_table;
pub mod schema;
pub mod sink;
mod spec;
mod value;

pub use asset_path::AssetPath;
pub use change::{ChangeEntry, ChangeFlags, ChangeList};
pub(crate) use copy::{author_spec, is_children_field};
pub use copy::{
    copy_spec, copy_spec_with, copy_spec_within, should_copy_children, should_copy_value, CopyChildren,
    CopyChildrenArgs, CopyValue, CopyValueArgs,
};
pub use data::{AbstractData, CowData, Data, DataError, Patch};
pub use expr::{Evaluation, EvaluationValue, Expr, StringEvaluation, StringSegment};
pub use file_format::{FileFormat, FileFormatCaps, WriteSeek};
pub(crate) use layer::{dry_run_layers, edit_layers};
pub use layer::{AuthoringError, EditError, Layer, LayerEdit, LayerSink, LayerSinkId, PendingLayerChange};
pub use layer_registry::LayerRegistry;
pub use ordering::{apply_ordering, element_cmp};
pub use path::{path, Path, PathComponent, PathComponents, PathElement};
pub use path_table::PathTable;
pub use schema::{ChildrenKey, FieldKey};
pub use spec::{
    AttributeSpec, AttributeSpecMut, AttributeSpecRef, PrimSpec, PrimSpecMut, PrimSpecRef, PropertySpec,
    PropertySpecMut, PropertySpecRef, PseudoRootSpec, PseudoRootSpecMut, PseudoRootSpecRef, RelationshipSpec,
    RelationshipSpecMut, RelationshipSpecRef, Spec, SpecData, SpecError, SpecMut, SpecRef, SpecType,
};
pub use value::{CastError, FromValueCast, Value, ValueConversionError};

#[repr(i32)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, FromRepr)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
pub enum Specifier {
    Def,
    Over,
    Class,
}

/// An enum that defines permission levels.
///
/// Permissions control which layers may refer to or express
/// opinions about a prim. Opinions expressed about a prim, or
/// relationships to that prim, by layers that are not allowed
/// permission to access the prim will be ignored.
#[repr(i32)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, FromRepr)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
pub enum Permission {
    Public,
    Private,
}

/// An enum that identifies variability types for attributes.
/// Variability indicates whether the attribute may vary over time and
/// value coordinates, and if its value comes through authoring or
/// or from its owner.
#[repr(i32)]
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, FromRepr)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
pub enum Variability {
    #[default]
    Varying,
    Uniform,
}

/// A time-coded `double` (C++ `SdfTimeCode`) — the value held by a
/// `timecode`-typed attribute (e.g. `UsdMediaSpatialAudio.startTime`). Unlike
/// a plain `double`, a `TimeCode` value is retimed by layer offsets during
/// composition.
///
/// This is the authored *value* type, distinct from a time-query *parameter*
/// (C++ `UsdTimeCode`, passed to `Attribute::get_at`). Read it with
/// `Attribute::get::<sdf::TimeCode>()` and author it with
/// `set(sdf::TimeCode(..))`; it round-trips through [`Value::TimeCode`].
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Default, derive_more::From)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct TimeCode(pub f64);

impl TimeCode {
    /// The wrapped time value.
    #[inline]
    pub fn value(self) -> f64 {
        self.0
    }
}

impl TryFrom<Value> for TimeCode {
    type Error = ValueConversionError;

    fn try_from(value: Value) -> Result<Self, Self::Error> {
        match value {
            Value::TimeCode(v) => Ok(v),
            other => ValueConversionError::err("TimeCode", &other),
        }
    }
}

/// Represents a time offset and scale between layers.
#[repr(C)]
#[derive(Debug, Clone, Copy, PartialEq, Pod, Zeroable)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct LayerOffset {
    /// Time offset.
    pub offset: f64,
    /// Scale factor.
    pub scale: f64,
}

impl Default for LayerOffset {
    fn default() -> Self {
        Self {
            offset: 0.0,
            scale: 1.0,
        }
    }
}

impl LayerOffset {
    /// Identity layer offset: offset 0, scale 1.
    pub const IDENTITY: LayerOffset = LayerOffset {
        offset: 0.0,
        scale: 1.0,
    };

    #[inline]
    pub fn new(offset: f64, scale: f64) -> Self {
        Self { offset, scale }
    }

    /// A pure time scaling `(0.0, scale)` with no offset. Composed onto another
    /// offset it scales without shifting — used to fold a `timeCodesPerSecond`
    /// retiming ratio into an arc's offset (spec 12.3.2).
    #[inline]
    pub fn scale_only(scale: f64) -> Self {
        Self { offset: 0.0, scale }
    }

    #[inline]
    pub fn is_valid(&self) -> bool {
        self.offset.is_finite() && self.scale.is_finite()
    }

    /// Returns `true` if this is the identity offset `(0.0, 1.0)`.
    #[inline]
    pub fn is_identity(&self) -> bool {
        self.offset == 0.0 && self.scale == 1.0
    }

    /// Applies this offset to a time value as `offset + scale * time` — the
    /// retiming a layer offset performs on the time coordinate of samples and
    /// clip schedules.
    #[inline]
    pub fn apply(&self, time: f64) -> f64 {
        self.offset + self.scale * time
    }

    /// Returns the inverse offset, undoing [`apply`](Self::apply): if `self`
    /// maps a source time `t` to `offset + scale * t`, the inverse maps that
    /// result back to `t`. The identity inverts to itself; a `scale == 0`
    /// offset has no inverse and yields the identity.
    #[inline]
    pub fn inverse(&self) -> LayerOffset {
        if self.scale == 0.0 {
            return LayerOffset::IDENTITY;
        }
        LayerOffset {
            offset: -self.offset / self.scale,
            scale: 1.0 / self.scale,
        }
    }

    /// Returns `true` if this offset is well-formed for composition:
    /// finite `offset` and a strictly positive, finite `scale`.
    ///
    /// Per spec 10.3.1.1 / 10.3.2.1.2, a non-positive scale is a composition
    /// error.
    #[inline]
    pub fn is_valid_composition(&self) -> bool {
        self.offset.is_finite() && self.scale.is_finite() && self.scale > 0.0
    }

    /// Returns this offset if valid for composition, or the identity otherwise.
    ///
    /// Matches OpenUSD behaviour of silently dropping back to identity when a
    /// non-positive or non-finite scale is authored.
    #[inline]
    pub fn sanitized(self) -> Self {
        if self.is_valid_composition() {
            self
        } else {
            Self::IDENTITY
        }
    }

    /// Concatenates `self` (outer / closer to root) with `inner` (deeper).
    ///
    /// Given two offsets where a time value `t` in the inner frame maps to
    /// the outer frame as `t * inner.scale + inner.offset`, and outer's own
    /// transform is `t * outer.scale + outer.offset`, the composed transform
    /// from the deepest frame to the outermost is:
    ///
    /// ```text
    /// offset = outer.offset + outer.scale * inner.offset
    /// scale  = outer.scale * inner.scale
    /// ```
    #[inline]
    pub fn concatenate(&self, inner: &LayerOffset) -> LayerOffset {
        LayerOffset {
            offset: self.offset + self.scale * inner.offset,
            scale: self.scale * inner.scale,
        }
    }
}

/// Represents a payload and all its meta data.
///
/// A payload represents a prim reference to an external layer. A payload
/// is similar to a prim reference (see SdfReference) with the major
/// difference that payloads are explicitly loaded by the user.
///
/// Unloaded payloads represent a boundary that lazy composition and
/// system behaviors will not traverse across, providing a user-visible
/// way to manage the working set of the scene.
#[derive(Debug, Default, Clone, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct Payload {
    /// The asset path to the external layer.
    #[cfg_attr(feature = "serde", serde(rename = "asset", skip_serializing_if = "String::is_empty"))]
    pub asset_path: String,
    /// The root prim path to the referenced prim in the external layer.
    #[cfg_attr(feature = "serde", serde(rename = "path", skip_serializing_if = "Path::is_empty"))]
    pub prim_path: Path,
    /// The layer offset to transform time.
    #[cfg_attr(
        feature = "serde",
        serde(rename = "layerOffset", skip_serializing_if = "Option::is_none")
    )]
    pub layer_offset: Option<LayerOffset>,
}

/// Represents a reference and all its meta data.
///
/// A reference is expressed on a prim in a given layer and it identifies a
/// prim in a layer stack. All opinions in the namespace hierarchy
/// under the referenced prim will be composed with the opinions in the
/// namespace hierarchy under the referencing prim.
#[derive(Debug, Default, Clone, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct Reference {
    /// The asset path to the external layer.
    #[cfg_attr(feature = "serde", serde(rename = "asset", skip_serializing_if = "String::is_empty"))]
    pub asset_path: String,
    /// The path to the referenced prim in the external layer.
    #[cfg_attr(feature = "serde", serde(rename = "path", skip_serializing_if = "Path::is_empty"))]
    pub prim_path: Path,
    /// The layer offset to transform time.
    #[cfg_attr(feature = "serde", serde(rename = "layerOffset"))]
    pub layer_offset: LayerOffset,
    /// The custom data associated with the reference.
    #[cfg_attr(
        feature = "serde",
        serde(rename = "customData", skip_serializing_if = "HashMap::is_empty")
    )]
    pub custom_data: HashMap<String, Value>,
}

mod list_op;

pub use list_op::ListOp;

/// A USD dictionary value (C++ `VtDictionary`): the payload of
/// [`Value::Dictionary`], keyed by name.
pub type Dictionary = std::collections::HashMap<String, Value>;

pub type IntListOp = ListOp<i32>;
pub type UintListOp = ListOp<u32>;

pub type Int64ListOp = ListOp<i64>;
pub type Uint64ListOp = ListOp<u64>;

pub type StringListOp = ListOp<String>;
pub type TokenListOp = ListOp<Token>;
pub type PathListOp = ListOp<Path>;
pub type ReferenceListOp = ListOp<Reference>;
pub type PayloadListOp = ListOp<Payload>;

pub type TimeSampleMap = Vec<(f64, Value)>;

/// A single namespace relocation `(source, target)`: the prim at `source` is
/// moved to `target` in composed namespace. An empty `target` is a deletion
/// that makes `source` a prohibited (invalid) child name. Mirrors C++
/// `SdfRelocate`, a `std::pair<SdfPath, SdfPath>`.
pub type Relocate = (Path, Path);

/// The ordered list of [`Relocate`]s authored in a layer's `relocates`
/// metadata. Mirrors C++ `SdfRelocates`, a `std::vector<SdfRelocate>`.
pub type RelocateList = Vec<Relocate>;

/// A boxed layer data source, used throughout the layer stack.
pub type LayerData = Box<dyn AbstractData>;

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn layer_offset_identity_is_identity() {
        assert!(LayerOffset::IDENTITY.is_identity());
        assert!(LayerOffset::default().is_identity());
        assert!(!LayerOffset::new(0.0, 2.0).is_identity());
        assert!(!LayerOffset::new(1.0, 1.0).is_identity());
    }

    #[test]
    fn layer_offset_valid_composition_rejects_non_positive_scale() {
        assert!(LayerOffset::new(10.0, 1.0).is_valid_composition());
        assert!(!LayerOffset::new(10.0, 0.0).is_valid_composition());
        assert!(!LayerOffset::new(10.0, -1.0).is_valid_composition());
        assert!(!LayerOffset::new(f64::INFINITY, 1.0).is_valid_composition());
        assert!(!LayerOffset::new(0.0, f64::NAN).is_valid_composition());
    }

    #[test]
    fn layer_offset_sanitized_drops_invalid_to_identity() {
        assert_eq!(LayerOffset::new(10.0, 2.0).sanitized(), LayerOffset::new(10.0, 2.0));
        assert_eq!(LayerOffset::new(5.0, -1.0).sanitized(), LayerOffset::IDENTITY);
        assert_eq!(LayerOffset::new(5.0, 0.0).sanitized(), LayerOffset::IDENTITY);
    }

    #[test]
    fn layer_offset_concatenate_matches_spec_formula() {
        let outer = LayerOffset::new(10.0, 2.0);
        let inner = LayerOffset::new(20.0, 1.0);
        // Matches BasicTimeOffset_root pcp.txt: (10,2) concat (20,1) = (50, 2).
        assert_eq!(outer.concatenate(&inner), LayerOffset::new(50.0, 2.0));
    }

    #[test]
    fn layer_offset_concatenate_is_associative() {
        let a = LayerOffset::new(10.0, 2.0);
        let b = LayerOffset::new(20.0, 0.5);
        let c = LayerOffset::new(5.0, 3.0);
        let ab_c = a.concatenate(&b).concatenate(&c);
        let a_bc = a.concatenate(&b.concatenate(&c));
        assert!((ab_c.offset - a_bc.offset).abs() < 1e-12);
        assert!((ab_c.scale - a_bc.scale).abs() < 1e-12);
    }

    #[test]
    fn layer_offset_identity_is_neutral() {
        let a = LayerOffset::new(10.0, 2.0);
        assert_eq!(a.concatenate(&LayerOffset::IDENTITY), a);
        assert_eq!(LayerOffset::IDENTITY.concatenate(&a), a);
    }

    #[test]
    fn layer_offset_inverse_undoes_apply() {
        // A dyadic scale round-trips exactly.
        let a = LayerOffset::new(10.0, 2.0);
        assert_eq!(a.inverse(), LayerOffset::new(-5.0, 0.5));
        assert_eq!(a.inverse().apply(a.apply(7.0)), 7.0);
        // A non-dyadic scale (e.g. a 1/3 retiming ratio) round-trips only to
        // within float rounding, not exactly.
        let b = LayerOffset::new(1.0, 3.0);
        assert!((b.inverse().apply(b.apply(7.0)) - 7.0).abs() < 1e-9);
        // The identity inverts to itself; a zero scale has no inverse.
        assert_eq!(LayerOffset::IDENTITY.inverse(), LayerOffset::IDENTITY);
        assert_eq!(LayerOffset::new(3.0, 0.0).inverse(), LayerOffset::IDENTITY);
    }
}