rust-gpu/crates/spirv-std/src/geometry.rs at bd97f845cdf8ca83fb418da44fb363881be9d29a · Rust-GPU/rust-gpu · GitHub

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//! Intrinsics for geometry shaders

#[cfg(target_arch = "spirv")]
use core::arch::asm;

/// Emits the current values of all output variables to the current output
/// primitive. After execution, the values of all output variables
/// are undefined.  Requires capability `Geometry`.
///
/// # Safety
/// This instruction must only be used when only one stream is present.
#[spirv_std_macros::gpu_only]
#[doc(alias = "OpEmitVertex")]
#[inline]
pub unsafe fn emit_vertex() {
    unsafe {
        asm! {
            "OpEmitVertex",
        }
    }
}

/// Finish the current primitive and start a new one. No vertex is emitted.
/// Requires capability `Geometry`.
///
/// # Safety
/// This instruction must only be used when only one stream is present.
#[spirv_std_macros::gpu_only]
#[doc(alias = "OpEndPrimitive")]
#[inline]
pub unsafe fn end_primitive() {
    unsafe {
        asm! {
            "OpEndPrimitive",
        }
    }
}

/// Emits the current values of all output variables to the current output
/// primitive. After execution, the values of all output variables
/// are undefined.
///
/// `STREAM` is the output-primitive stream number.
///
/// Requires capability `GeometryStreams`.
///
/// # Safety
/// This instruction must only be used when multiple streams are present.
#[spirv_std_macros::gpu_only]
#[doc(alias = "OpEmitStreamVertex")]
#[inline]
// FIXME(eddyb) why does this require `i64` instead of `i32`?
pub unsafe fn emit_stream_vertex<const STREAM: i64>() {
    unsafe {
        asm! {
            "%i64 = OpTypeInt 64 1",
            "%stream = OpConstant %i64 {stream}",
            "OpEmitStreamVertex %stream",
            stream = const STREAM,
        }
    }
}

/// Finish the current primitive and start a new one. No vertex is emitted.
///
/// `STREAM` is the output-primitive stream number.
///
/// Requires capability `GeometryStreams`.
///
/// # Safety
/// This instruction must only be used when multiple streams are present.
#[spirv_std_macros::gpu_only]
#[doc(alias = "OpEndStreamPrimitive")]
#[inline]
// FIXME(eddyb) why does this require `i64` instead of `i32`?
pub unsafe fn end_stream_primitive<const STREAM: i64>() {
    unsafe {
        asm! {
            "%i64 = OpTypeInt 64 1",
            "%stream = OpConstant %i64 {stream}",
            "OpEndStreamPrimitive %stream",
            stream = const STREAM,
        }
    }
}