naga/front/spv/
null.rs

1use alloc::vec;
2
3use super::Error;
4use crate::arena::{Arena, Handle};
5
6/// Create a default value for an output built-in.
7pub fn generate_default_built_in(
8    built_in: Option<crate::BuiltIn>,
9    ty: Handle<crate::Type>,
10    global_expressions: &mut Arena<crate::Expression>,
11    span: crate::Span,
12) -> Result<Handle<crate::Expression>, Error> {
13    let expr = match built_in {
14        Some(crate::BuiltIn::Position { .. }) => {
15            let zero = global_expressions
16                .append(crate::Expression::Literal(crate::Literal::F32(0.0)), span);
17            let one = global_expressions
18                .append(crate::Expression::Literal(crate::Literal::F32(1.0)), span);
19            crate::Expression::Compose {
20                ty,
21                components: vec![zero, zero, zero, one],
22            }
23        }
24        Some(crate::BuiltIn::PointSize) => crate::Expression::Literal(crate::Literal::F32(1.0)),
25        Some(crate::BuiltIn::FragDepth) => crate::Expression::Literal(crate::Literal::F32(0.0)),
26        Some(crate::BuiltIn::SampleMask) => {
27            crate::Expression::Literal(crate::Literal::U32(u32::MAX))
28        }
29        // Note: `crate::BuiltIn::ClipDistance` is intentionally left for the default path
30        _ => crate::Expression::ZeroValue(ty),
31    };
32    Ok(global_expressions.append(expr, span))
33}