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46 changes: 33 additions & 13 deletions crates/spirv-std/src/matrix.rs
Original file line number Diff line number Diff line change
@@ -1,31 +1,39 @@
//! a set of common SPIR-V Matrices, used for intrinsics

use core::fmt::{Debug, Display, Formatter};
use glam::{Affine3A, Mat3, Mat3A, Mat4, Vec3, Vec3A};

/// A Matrix with 4 columns of [`Vec3`], very similar to glam's [`Affine3A`].
///
/// Primarily used in ray tracing extensions to represent object rotation, scale and translation.
///
/// # Limitations
/// These Limitations apply to all structs marked with `#[spirv(matrix)]`, which `Matrix4x3` is the only one in
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This feels a bit too inward facing. Just state the limitations. I guess you can optionally ask for a task.

/// `spirv-std`:
/// * Cannot be used within buffers, push constants or anything that requires an "explicit layout". Use [`Affine3A`],
/// [`Mat4`] or the combination of [`Mat3`] with [`Vec3`] instead and convert them to `Matrix4x3` in the shader.
/// * There may be other situations where this type may surprisingly fail!
#[derive(Clone, Copy, Default, PartialEq)]
#[repr(C)]
#[spirv(matrix)]
#[allow(missing_docs)]
pub struct Matrix4x3 {
pub x: Vec3A,
pub y: Vec3A,
pub z: Vec3A,
pub w: Vec3A,
pub x_axis: Vec3A,
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Why did this change? Is it more or less consistent with other APIs?

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@Firestar99 Firestar99 Oct 16, 2025

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More consistent, now the member names are the same of glam's matrices. Split it out into a separate commit to make it easier to reason about

impl Matrix4x3 {
/// Convert from glam's [`Affine3A`]
pub fn from_affine3a(affine: Affine3A) -> Self {
Self {
x_axis: affine.x_axis,
y_axis: affine.y_axis,
z_axis: affine.z_axis,
w_axis: affine.w_axis,
}
}

pub y_axis: Vec3A,
pub z_axis: Vec3A,
pub w_axis: Vec3A,
}

/// The `from_*` fn signatures should match [`Affine3A`], to make it easier to switch to [`Affine3A`] later.
/// The `to_*` fn signatures are custom
/// The `to_*` fn signatures are custom.
impl Matrix4x3 {
/// Convert from glam's [`Affine3A`]
pub fn from_affine3a(affine: Affine3A) -> Self {
Self {
x: affine.x_axis,
y: affine.y_axis,
z: affine.z_axis,
w: affine.w_axis,
x_axis: affine.x_axis,
y_axis: affine.y_axis,
z_axis: affine.z_axis,
w_axis: affine.w_axis,
}
}

Expand Down Expand Up @@ -53,11 +61,11 @@ impl Matrix4x3 {
pub fn to_affine3a(self) -> Affine3A {
Affine3A {
matrix3: Mat3A {
x_axis: self.x,
y_axis: self.y,
z_axis: self.z,
x_axis: self.x_axis,
y_axis: self.y_axis,
z_axis: self.z_axis,
},
translation: self.w,
translation: self.w_axis,
}
}

Expand All @@ -76,3 +84,15 @@ impl Matrix4x3 {
Mat4::from(self.to_affine3a())
}
}

impl Debug for Matrix4x3 {
fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
Debug::fmt(&self.to_mat4(), f)
}
}

impl Display for Matrix4x3 {
fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
Display::fmt(&self.to_mat4(), f)
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ use core::mem::offset_of;
use core::ops::Range;
use experiments::*;
use spirv_std::glam::*;
use spirv_std::matrix::Matrix4x3;

pub struct BumpAlloc(usize);

Expand Down Expand Up @@ -61,6 +62,7 @@ pub fn eval_layouts(gid: u32, out: &mut [u32]) {
0x11 => write_layout!(out, offset, Struct0x11(a, b)),
0x12 => write_layout!(out, offset, Struct0x12(a, b, c, d, e)),
0x13 => write_layout!(out, offset, Struct0x13(a)),
0x14 => write_layout!(out, offset, Matrix4x3(x_axis, y_axis, z_axis, w_axis)),

// mat
0x20 => write_layout!(out, offset, Mat2()), // private members
Expand Down