Struct Transform

pub struct Transform { /* private fields */ }

An affine 4×4 transform in USD’s row-vector layout.

Values are f64 so that georeferenced translations keep millimetre precision. The last column is always (0, 0, 0, 1).

Implementations

impl Transform

pub const IDENTITY: Self

The transform that leaves every point where it is.

pub fn from_rows(rows: [[f64; 4]; 4]) -> Result<Self, DecodeError>

Builds a transform from rows in the file’s layout (translation in the last row). Fails if the last column is not (0, 0, 0, 1) or a value is not finite.

pub fn from_translation(t: Vec3) -> Self

A pure translation.

pub fn from_attribute(value: &Value) -> Result<Self, DecodeError>

Decodes the value of a ATTRIBUTE (usd::xformop) attribute, an object whose transform field holds the matrix.

use openbim_ifcx_geometry::transform::Transform;

let value = serde_json::json!({"transform": [
    [1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [5, 0, 2, 1]
]});
let t = Transform::from_attribute(&value)?;
assert_eq!(t.translation(), [5.0, 0.0, 2.0]);
assert_eq!(t.transform_point([1.0, 1.0, 1.0]), [6.0, 1.0, 3.0]);

pub fn from_matrix_json(value: &Value) -> Result<Self, DecodeError>

Decodes the matrix itself: four arrays of four numbers, rows first.

pub fn rows(&self) -> &[[f64; 4]; 4]

The rows in the file’s layout; the translation is rows()[3].

pub fn translation(&self) -> Vec3

The translation part.

pub fn to_column_major(&self) -> [f64; 16]

The 16 values in column-major order of the equivalent column-vector matrix: the layout of glTF node.matrix and three.js Matrix4.elements. This equals the file’s rows flattened in order.

pub fn then(&self, outer: &Transform) -> Transform

The transform that applies self first and then outer; in the row-vector layout this is the product self · outer.

For a node with local transform local under a parent with world transform parent, the node’s world transform is local.then(&parent).

pub fn transform_point(&self, p: Vec3) -> Vec3

Maps a point, including the translation.

pub fn transform_vector(&self, v: Vec3) -> Vec3

Maps a direction, ignoring the translation. Normals need the inverse transpose instead when the transform scales unevenly.

pub fn determinant(&self) -> f64

Determinant of the 3×3 linear part. A negative value means the transform mirrors, which reverses triangle winding.

Trait Implementations

impl Clone for Transform

fn clone(&self) -> Transform

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Transform

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Transform

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for Transform

fn eq(&self, other: &Transform) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Transform

impl StructuralPartialEq for Transform