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use {
    super::{native::ShaderNative, pad::Padding},
    bytemuck::Pod,
};

/// Default layout for [`Repr`].
/// Can be used for both uniforms storage buffers.
#[derive(Clone, Copy, Debug)]
pub enum Std140 {}

/// Can be used only for storage buffers.
#[derive(Clone, Copy, Debug)]
pub enum Std430 {}

/// Type that can be represented in shader.
pub trait ShaderRepr<T = Std140> {
    const ALIGN_MASK: usize;
    const ARRAY_PADDING: usize;

    /// Type with matching layout.
    type Type: Pod;

    /// Padding required after field of `Self::Type` for arrays.
    type ArrayPadding: Padding;

    /// Copy data in this type into its representation.
    fn copy_to_repr(&self, repr: &mut Self::Type);
}

impl<T> ShaderRepr<Std140> for T
where
    T: ShaderNative,
{
    const ALIGN_MASK: usize = <T as ShaderNative>::ALIGN_MASK;
    const ARRAY_PADDING: usize = <T as ShaderNative>::ARRAY_PADDING_140;
    type Type = T;
    type ArrayPadding = <T as ShaderNative>::ArrayPadding140;

    fn copy_to_repr(&self, repr: &mut T) {
        *repr = *self
    }
}

impl<T> ShaderRepr<Std430> for T
where
    T: ShaderNative,
{
    const ALIGN_MASK: usize = <T as ShaderNative>::ALIGN_MASK;
    const ARRAY_PADDING: usize = <T as ShaderNative>::ARRAY_PADDING_430;
    type Type = T;
    type ArrayPadding = <T as ShaderNative>::ArrayPadding430;

    fn copy_to_repr(&self, repr: &mut T) {
        *repr = *self
    }
}