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use std::alloc::Layout;
use std::borrow::Cow;
use std::marker::PhantomData;
use seq_macro::seq;
use zerocopy::{FromBytes, Immutable, IntoBytes, KnownLayout};
use crate::mesh::VertexAttrType;
pub trait VertexAttrValue:
IntoBytes + FromBytes + KnownLayout + Immutable + 'static
{
fn ty() -> VertexAttrType;
}
impl VertexAttrValue for f32
{
fn ty() -> VertexAttrType
{
VertexAttrType::Float32
}
}
impl<const LEN: usize> VertexAttrValue for [f32; LEN]
{
fn ty() -> VertexAttrType
{
VertexAttrType::Float32Array { length: LEN }
}
}
#[derive(Debug)]
pub struct NamedVertexAttr<'name, Value: VertexAttrValue>
{
pub name: &'name str,
pub value: Value,
}
#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct VertexAttrProperties
{
pub name: Cow<'static, str>,
pub ty: VertexAttrType,
pub layout: Layout,
pub byte_offset: usize,
}
#[derive(Debug)]
pub struct VertexAttrInfo
{
pub name: Cow<'static, str>,
pub ty: VertexAttrType,
}
#[derive(Debug, Clone, Default)]
pub struct VertexBuffer
{
buf: Vec<u8>,
vertex_size: usize,
vertex_attr_props: Vec<VertexAttrProperties>,
}
impl VertexBuffer
{
pub fn with_capacity(vertex_attrs: &[VertexAttrInfo], capacity: usize) -> Self
{
let mut vertex_attr_props = vertex_attrs
.iter()
.map(|VertexAttrInfo { name, ty }| VertexAttrProperties {
name: name.clone(),
ty: ty.clone(),
layout: ty.layout(),
byte_offset: 0,
})
.collect::<Vec<_>>();
let mut vertex_layout = Layout::new::<()>();
for VertexAttrProperties {
name: _,
ty: _,
layout: vertex_attr_layout,
byte_offset: vertex_attr_byte_offset,
} in &mut vertex_attr_props
{
let (new_struct_layout, byte_offset) =
vertex_layout.extend(*vertex_attr_layout).unwrap();
*vertex_attr_byte_offset = byte_offset;
vertex_layout = new_struct_layout;
}
let vertex_layout = vertex_layout.pad_to_align();
Self {
buf: Vec::with_capacity(vertex_layout.size() * capacity),
vertex_size: vertex_layout.size(),
vertex_attr_props,
}
}
pub fn push<'name, VertexAttrs: NamedVertexAttrs<'name>>(
&mut self,
vertex: VertexAttrs,
)
{
assert_eq!(
self.vertex_attr_props.len(),
vertex.vertex_attr_cnt(),
"Vertex has incorrect amount of attributes"
);
if self.buf.spare_capacity_mut().len() < self.vertex_size {
self.buf.reserve_exact(self.vertex_size * (self.len() / 2));
}
let spare_capacity = self.buf.spare_capacity_mut();
let vertex_attrs = vertex.vertex_attrs();
for (vertex_attr_name, vertex_attr_bytes, vertex_attr_ty) in vertex_attrs {
let vertex_attr_props = self
.vertex_attr_props
.iter()
.find(|vertex_attr_props| vertex_attr_props.name == vertex_attr_name)
.unwrap();
assert_eq!(vertex_attr_ty, vertex_attr_props.ty);
let start_offset = vertex_attr_props.byte_offset;
let end_offset = start_offset + vertex_attr_props.layout.size();
spare_capacity[start_offset..end_offset]
.write_copy_of_slice(vertex_attr_bytes);
}
unsafe {
self.buf.set_len(self.buf.len() + self.vertex_size);
}
}
pub fn vertex_attr_props(&self) -> &[VertexAttrProperties]
{
&self.vertex_attr_props
}
pub fn len(&self) -> usize
{
assert_eq!(self.buf.len() % self.vertex_size, 0, "Invalid length");
self.buf.len() / self.vertex_size
}
pub fn vertex_size(&self) -> usize
{
self.vertex_size
}
pub fn as_bytes(&self) -> &[u8]
{
&self.buf
}
pub fn iter<VertexAttr: VertexAttrValue>(
&self,
vertex_attr_name: &str,
) -> Iter<'_, VertexAttr>
{
let vertex_attr_props = self
.vertex_attr_props
.iter()
.find(|vertex_attr_props| vertex_attr_props.name == vertex_attr_name)
.unwrap();
assert_eq!(VertexAttr::ty(), vertex_attr_props.ty);
Iter {
buf: self,
vertex_attr_props,
curr_index: 0,
_pd: PhantomData,
}
}
}
pub struct Iter<'a, VertexAttr: VertexAttrValue>
{
buf: &'a VertexBuffer,
vertex_attr_props: &'a VertexAttrProperties,
curr_index: usize,
_pd: PhantomData<VertexAttr>,
}
impl<'a, VertexAttr: VertexAttrValue> Iterator for Iter<'a, VertexAttr>
{
type Item = &'a VertexAttr;
fn next(&mut self) -> Option<Self::Item>
{
let start_offset =
(self.buf.vertex_size * self.curr_index) + self.vertex_attr_props.byte_offset;
let end_offset = start_offset + self.vertex_attr_props.layout.size();
let bytes = self.buf.buf.get(start_offset..end_offset)?;
self.curr_index += 1;
Some(VertexAttr::ref_from_bytes(bytes).unwrap())
}
}
pub trait NamedVertexAttrs<'name>
{
fn vertex_attr_cnt(&self) -> usize;
fn vertex_attrs(&self) -> impl Iterator<Item = (&'name str, &[u8], VertexAttrType)>;
}
macro_rules! impl_named_vertex_attrs {
($cnt: tt) => {
seq!(I in 0..$cnt {
impl<'name, #(VertexAttr~I: VertexAttrValue,)*>
NamedVertexAttrs<'name> for (#(NamedVertexAttr<'name, VertexAttr~I>,)*)
{
fn vertex_attr_cnt(&self) -> usize
{
$cnt
}
fn vertex_attrs(&self)
-> impl Iterator<Item = (&'name str, &[u8], VertexAttrType)>
{
[#(
(self.I.name, self.I.value.as_bytes(), VertexAttr~I::ty()),
)*].into_iter()
}
}
});
};
}
seq!(I in 0..16 {
impl_named_vertex_attrs!(I);
});
|
