Expand description
Creating and crafting a tasty slab of memory.
§What
crabslab
is a slab implementation focused on marshalling data between CPUs and GPUs.
§But Why?
It’s hard to get data onto GPUs in the form you expect.
To marshall your data correctly you must know about the alignment and sizes of the underlying representation of your data. This will often surprise you!
Working with a slab on the other hand, only requires that your types can be written into an array and read from an array.
§Opinion
Working with shaders is much easier using a slab.
Shader code can be written in Rust with rust-gpu
,
which will enable you to use this crate on both CPU and GPU code.
§rust-gpu
This crate was made to work with rust-gpu
.
Specifically, with this crate it is possible to pack your types into a buffer on the CPU
and then read your types from the slab on the GPU (in Rust).
§Other no-std platforms
Even though this crate was written with rust-gpu
in mind, it should work in other no-std
contexts.
§And How
The idea is simple - crabslab
helps you manage a heap of contiguous u32
s (roughly in the form of Vec<u32>
).
Types implement the trait SlabItem
which writes the type into an index of the slab as contiguous u32
s and also
reads them out symmetrically.
crabslab
includes:
- a few traits:
Slab
GrowableSlab
SlabItem
- a derive macro for
SlabItem
for your types - a few new structs for working with slabs
Id
Array
Offset
- a helper struct
CpuSlab
which wraps anything implementingGrowableSlab
- a feature-gated helper for using slabs with
wgpu
-WgpuBuffer
- feature for deriving
SlabItem
forglam
types
§Example
use crabslab::{CpuSlab, Slab, GrowableSlab, SlabItem, Id};
use glam::{Vec3, Vec4};
#[derive(Debug, Default, SlabItem, PartialEq)]
struct Light {
direction: Vec3,
color: Vec4,
inner_cutoff: f32,
outer_cutoff: f32,
is_on: bool
}
impl Light {
fn standard() -> Self {
Light {
direction: Vec3::NEG_Z, // pointing down
color: Vec4::ONE, // white
inner_cutoff: 0.5,
outer_cutoff: 2.6,
is_on: true
}
}
}
fn cpu_code() -> (Id<Light>, Vec<u32>) {
// Create a new slab on the CPU-side.
// NOTE: For simplicity here we use `Vec<u32>` but if we were using `wgpu`
// we could use `crabslab::WgpuBuffer` instead of `Vec<u32>`.
// The API is the same.
let light = Light::standard();
let mut slab = CpuSlab::new(vec![]);
let id = slab.append(&light);
(id, slab.into_inner())
}
fn shader_code(light_id: Id<Light>, slab: &[u32]) {
let light = slab.read(light_id);
assert_eq!(Light::standard(), light);
}
let (light_id, slab) = cpu_code();
// marshalling your data depends on which GPU library you are using...
shader_code(light_id, &slab);
Modules§
Structs§
- A pointer to contiguous
T
elements in a slab. - A wrapper around a
GrowableSlab
that provides convenience methods for working with CPU-side slabs. - An identifier that can be used to read or write a type from/into the slab.
- The slab offset of field
F
within a typeT
. - A slab buffer used by the stage to store heterogeneous objects.
Enums§
- Errors that can occur when using a
WgpuBuffer
as slab storage.
Constants§
u32
value of anId
that does not point to any item.
Traits§
- Trait for slabs of
u32
s that can store many types, and can grow to fit. - Trait for slabs of
u32
s that can store many types. - Determines the “size” of a type when stored in a slab of
&[u32]
, and how to read/write it from/to the slab.
Functions§
- Proxy for
u32::saturating_sub
. - Print the slab’s index, binary representation, integer value, and float value.
Derive Macros§
- Derives
SlabItem
for a struct.