openusd 0.4.0

Rust native USD library
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

use std::collections::HashMap;

use openusd::sdf::{self, ChildrenKey, FieldKey, LayerOffset, ListOp, Reference, SpecType, Specifier, Value};
use openusd::usda::TextWriter;

fn main() -> anyhow::Result<()> {
    write_spheres("sphere.usda")?;
    write_scene("scene.usda")?;
    Ok(())
}

fn write_spheres(path: &str) -> anyhow::Result<()> {
    let mut data = sdf::Data::new();

    let root = sdf::Path::abs_root();
    let root_spec = data.create_spec(root.clone(), SpecType::PseudoRoot);
    root_spec.add(FieldKey::DefaultPrim, Value::Token("BlueSphere".into()));
    root_spec.add(
        ChildrenKey::PrimChildren,
        Value::TokenVec(vec!["BlueSphere".into(), "GreenSphere".into(), "RedSphere".into()]),
    );

    add_sphere(&mut data, "/BlueSphere", [0.0, 0.0, 1.0])?;
    add_sphere(&mut data, "/GreenSphere", [0.0, 1.0, 0.0])?;
    add_sphere(&mut data, "/RedSphere", [1.0, 0.0, 0.0])?;

    TextWriter::write_to_file(&data, path)?;
    println!("Wrote {} spec(s) to {path}", data.len());
    Ok(())
}

fn add_sphere(data: &mut sdf::Data, prim_path: &str, color: [f32; 3]) -> anyhow::Result<()> {
    let prim = sdf::path(prim_path)?;
    let prim_spec = data.create_spec(prim.clone(), SpecType::Prim);
    prim_spec.add(FieldKey::Specifier, Value::Specifier(Specifier::Def));
    prim_spec.add(FieldKey::TypeName, Value::Token("Sphere".into()));
    prim_spec.add(
        ChildrenKey::PropertyChildren,
        Value::TokenVec(vec!["primvars:displayColor".into()]),
    );

    let color_prop = prim.append_property("primvars:displayColor")?;
    let attr_spec = data.create_spec(color_prop, SpecType::Attribute);
    attr_spec.add(FieldKey::TypeName, Value::Token("color3f[]".into()));
    attr_spec.add(FieldKey::Default, Value::Vec3fVec(vec![color]));

    Ok(())
}

/// Write `scene.usda` — a single prim with a `color` variant set that references
/// one of the three spheres from `sphere.usda` depending on the selected variant.
fn write_scene(path: &str) -> anyhow::Result<()> {
    let mut data = sdf::Data::new();

    let root = sdf::Path::abs_root();
    let root_spec = data.create_spec(root.clone(), SpecType::PseudoRoot);
    root_spec.add(FieldKey::DefaultPrim, Value::Token("ColoredSphere".into()));
    root_spec.add(ChildrenKey::PrimChildren, Value::TokenVec(vec!["ColoredSphere".into()]));

    // /ColoredSphere — owns the variant set.
    let sphere = sdf::path("/ColoredSphere")?;
    let sphere_spec = data.create_spec(sphere.clone(), SpecType::Prim);
    sphere_spec.add(FieldKey::Specifier, Value::Specifier(Specifier::Def));

    // Declare the "color" variant set and choose "blue" as the default selection.
    sphere_spec.add(
        FieldKey::VariantSetNames,
        Value::TokenListOp(ListOp {
            prepended_items: vec!["color".into()],
            ..Default::default()
        }),
    );
    sphere_spec.add(
        FieldKey::VariantSelection,
        Value::VariantSelectionMap({
            let mut map = HashMap::new();
            map.insert("color".into(), "blue".into());
            map
        }),
    );
    sphere_spec.add(ChildrenKey::VariantSetChildren, Value::TokenVec(vec!["color".into()]));

    // /ColoredSphere{color=} — the variant set spec.
    let vset_path = sdf::Path::new("/ColoredSphere{color=}")?;
    let vset_spec = data.create_spec(vset_path, SpecType::VariantSet);
    vset_spec.add(
        ChildrenKey::VariantChildren,
        Value::TokenVec(vec!["blue".into(), "green".into(), "red".into()]),
    );

    // Individual variant specs, each referencing a different sphere prim.
    add_variant(&mut data, "/ColoredSphere", "color", "blue", None)?;
    add_variant(&mut data, "/ColoredSphere", "color", "green", Some("/GreenSphere"))?;
    add_variant(&mut data, "/ColoredSphere", "color", "red", Some("/RedSphere"))?;

    TextWriter::write_to_file(&data, path)?;
    println!("Wrote {} spec(s) to {path}", data.len());
    Ok(())
}

/// Insert a variant spec that references `target_prim` inside `sphere.usda`.
/// When `target_prim` is `None` the reference omits an explicit prim path,
/// so USD resolves to the layer's `defaultPrim`.
fn add_variant(
    data: &mut sdf::Data,
    prim_path: &str,
    set_name: &str,
    variant_name: &str,
    target_prim: Option<&str>,
) -> anyhow::Result<()> {
    let variant_path = sdf::Path::new(&format!("{prim_path}{{{set_name}={variant_name}}}"))?;
    let variant_spec = data.create_spec(variant_path, SpecType::Variant);

    let prim_path = match target_prim {
        Some(p) => sdf::path(p)?,
        None => sdf::Path::default(),
    };

    let ref_list = ListOp::<Reference> {
        prepended_items: vec![Reference {
            asset_path: "./sphere.usda".into(),
            prim_path,
            layer_offset: LayerOffset::IDENTITY,
            custom_data: HashMap::new(),
        }],
        ..Default::default()
    };
    variant_spec.add(FieldKey::References, Value::ReferenceListOp(ref_list));

    Ok(())
}