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use super::Error;
use crate::arena::{Arena, Handle};
/// Create a default value for an output built-in.
pub fn generate_default_built_in(
built_in: Option<crate::BuiltIn>,
ty: Handle<crate::Type>,
const_expressions: &mut Arena<crate::Expression>,
span: crate::Span,
) -> Result<Handle<crate::Expression>, Error> {
let expr = match built_in {
Some(crate::BuiltIn::Position { .. }) => {
let zero = const_expressions
.append(crate::Expression::Literal(crate::Literal::F32(0.0)), span);
let one = const_expressions
.append(crate::Expression::Literal(crate::Literal::F32(1.0)), span);
crate::Expression::Compose {
ty,
components: vec![zero, zero, zero, one],
}
}
Some(crate::BuiltIn::PointSize) => crate::Expression::Literal(crate::Literal::F32(1.0)),
Some(crate::BuiltIn::FragDepth) => crate::Expression::Literal(crate::Literal::F32(0.0)),
Some(crate::BuiltIn::SampleMask) => {
crate::Expression::Literal(crate::Literal::U32(u32::MAX))
}
// Note: `crate::BuiltIn::ClipDistance` is intentionally left for the default path
_ => crate::Expression::ZeroValue(ty),
};
Ok(const_expressions.append(expr, span))
}
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