pebble/wgpu/
mesh.rs

1use crate::{
2    assets::upload::Asset,
3    wgpu::{
4        backend::WGPUBackend,
5        buffer::Buffer,
6        buffers::BufferBuilder,
7        flags::BufferUsages,
8        vertex_format::{VertexAttribute, VertexBufferLayout, VertexFormat, VertexStepMode},
9    },
10};
11
12/// Standard per-vertex data: position, UV, normal, and tangent (`w` is the
13/// bitangent handedness sign, ±1 — cross `normal` with `tangent.xyz` and
14/// scale by `tangent.w` to get the bitangent).
15///
16/// Occupies vertex buffer locations 0–3 — [`InstanceVertex::layout`]
17/// deliberately starts at location 4 to leave room for this, so pairing
18/// them in the same pipeline doesn't collide. Adding a 5th attribute here
19/// would need a matching shift there.
20#[repr(C)]
21#[derive(Copy, Clone, Default, bytemuck::Pod, bytemuck::Zeroable)]
22pub struct Vertex {
23    pub position: glam::Vec3,
24    pub tex_coords: glam::Vec2,
25    pub normal: glam::Vec3,
26    pub tangent: glam::Vec4,
27}
28
29impl Vertex {
30    pub fn new(
31        position: glam::Vec3,
32        tex_coords: glam::Vec2,
33        normal: glam::Vec3,
34        tangent: glam::Vec4,
35    ) -> Self {
36        Self {
37            position,
38            tex_coords,
39            normal,
40            tangent,
41        }
42    }
43
44    pub fn layout() -> VertexBufferLayout {
45        VertexBufferLayout {
46            array_stride: std::mem::size_of::<Vertex>() as u64,
47            step_mode: VertexStepMode::Vertex,
48            attributes: vec![
49                VertexAttribute { format: VertexFormat::Float32x3, offset: 0, shader_location: 0 }, // position
50                VertexAttribute { format: VertexFormat::Float32x2, offset: 12, shader_location: 1 }, // tex_coords
51                VertexAttribute { format: VertexFormat::Float32x3, offset: 20, shader_location: 2 }, // normal
52                VertexAttribute { format: VertexFormat::Float32x4, offset: 32, shader_location: 3 }, // tangent
53            ],
54        }
55    }
56}
57
58/// Per-instance vertex data. Carries a model matrix as four `Vec4` columns,
59/// passed as vertex attributes with `step_mode: Instance`.
60#[repr(C)]
61#[derive(Copy, Clone, Default, bytemuck::Pod, bytemuck::Zeroable)]
62pub struct InstanceVertex {
63    pub model: glam::Mat4,
64}
65
66impl InstanceVertex {
67    pub fn new(model: glam::Mat4) -> Self {
68        Self { model }
69    }
70
71    pub fn layout() -> VertexBufferLayout {
72        VertexBufferLayout {
73            array_stride: std::mem::size_of::<InstanceVertex>() as u64,
74            step_mode: VertexStepMode::Instance,
75            attributes: vec![
76                VertexAttribute { format: VertexFormat::Float32x4, offset: 0, shader_location: 4 }, // model col 0
77                VertexAttribute { format: VertexFormat::Float32x4, offset: 16, shader_location: 5 }, // model col 1
78                VertexAttribute { format: VertexFormat::Float32x4, offset: 32, shader_location: 6 }, // model col 2
79                VertexAttribute { format: VertexFormat::Float32x4, offset: 48, shader_location: 7 }, // model col 3
80            ],
81        }
82    }
83}
84
85/// Source data for [`GPUMesh`]: a plain vertex/index list, uploaded as-is.
86pub struct MeshDescriptor {
87    pub vertices: Vec<Vertex>,
88    pub indices: Vec<u32>,
89}
90
91/// A mesh uploaded to the GPU. `index_buffer`/`index_count` must stay in
92/// sync if you ever mutate one after construction — there's no invariant
93/// check, so a mismatched pair silently draws garbage or the wrong index
94/// range.
95pub struct GPUMesh {
96    pub vertex_buffer: Buffer,
97    pub index_buffer: Buffer,
98    pub index_count: u32,
99}
100
101impl Asset<WGPUBackend> for GPUMesh {
102    type Source = MeshDescriptor;
103    type Deps<'a> = ();
104
105    fn upload<'a>(source: &MeshDescriptor, backend: &WGPUBackend, _deps: &()) -> Option<Self> {
106        let vertex_buffer = BufferBuilder::new()
107            .label("Mesh Vertex Buffer")
108            .usage(BufferUsages::VERTEX)
109            .data(bytemuck::cast_slice(source.vertices.as_slice()))
110            .build(backend);
111        let index_buffer = BufferBuilder::new()
112            .label("Mesh Index Buffer")
113            .usage(BufferUsages::INDEX)
114            .data(bytemuck::cast_slice(&source.indices))
115            .build(backend);
116        Some(Self {
117            vertex_buffer,
118            index_buffer,
119            index_count: source.indices.len() as u32,
120        })
121    }
122}
123
124crate::wgpu::plugin_macros::asset_plugin! {
125    /// Registers the [`GPUMesh`] asset pipeline (`Assets<MeshDescriptor>` →
126    /// `ProcessedAssets<GPUMesh>`). Included by
127    /// [`WGPUPlugin`](super::backend::WGPUPlugin); add directly only if you're
128    /// assembling the `wgpu` module's plugins by hand.
129    MeshPlugin, GPUMesh
130}
pebble/wgpu/mesh.rs

pebble/wgpu/
mesh.rs
