1import bevy_pbr::render::{forward_io::VertexOutput, mesh_bindings::mesh};
2import bevy_render::bindless::{bindless_samplers_filtering, bindless_textures_2d};
3
4/// The custom data that we extract from the ECS and expose to this shader.
5struct CustomMaterialData {
6    /// The tint color for the mesh.
7    color: vec3<f32>,
8    /// Padding to pad this out to a multiple of 16 bytes.
9    pad: u32,
10}
11
12/// The array of material data that Bevy supplies.
13///
14/// We need to declare this type because
15/// `binding_array<array<CustomMaterialData>>` isn't currently accepted by Naga.
16/// We have to factor the `array<CustomMaterialData>` out into a separate type.
17struct CustomMaterialDataArray {
18    data_array: array<CustomMaterialData>,
19}
20
21@if(BINDLESS) {
22
23/// The bindings table for bindless mode.
24///
25/// These are indexes into the various arrays.
26struct CustomMaterialBindings {
27    material: u32,              // 0
28    /// The index of the data for this instance in the `CustomMaterialDataArray`.
29    data: u32,                  // 1
30    /// The index of the color texture for this instance in the
31    /// `bindless_textures_2d`.
32    color_texture: u32,         // 2
33    /// The index of the sampler for this instance in the
34    /// `bindless_samplers_filtering`.
35    color_texture_sampler: u32, // 3
36}
37
38@group(constants::MATERIAL_BIND_GROUP) @binding(0) var<storage> material_indices:
39    array<CustomMaterialBindings>;
40@group(constants::MATERIAL_BIND_GROUP) @binding(4) var<storage> material_data:
41    binding_array<CustomMaterialDataArray>;
42
43} @else {
44
45@group(constants::MATERIAL_BIND_GROUP) @binding(1) var<storage> material_data: CustomMaterialDataArray;
46@group(constants::MATERIAL_BIND_GROUP) @binding(2) var color_texture: texture_2d<f32>;
47@group(constants::MATERIAL_BIND_GROUP) @binding(3) var color_texture_sampler: sampler;
48
49}
50
51@fragment
52fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
53    // The tag stores the index of the data in the data array.
54    let tag = mesh[in.instance_index].tag;
55
56@if(BINDLESS) {
57
58    // Look up the bindless slot for this mesh.
59    let slot = mesh[in.instance_index].material_and_lightmap_bind_group_slot & 0xffffu;
60
61    // Unpack the bindless indices.
62    let data_index = material_indices[slot].data;
63    let color_texture_index = material_indices[slot].color_texture;
64    let color_texture_sampler_index = material_indices[slot].color_texture_sampler;
65
66    // Grab the color from the material data array.
67    //
68    // Note that there are two levels of arrays here: the binding array and the
69    // data array. The binding array should only have one element in this case,
70    // but Bevy still supplies a binding array because it's legal for different
71    // materials to have different `ShaderBuffer` bindings, even though in our
72    // case all materials are bound to the same buffer. The data array contains
73    // all of the instance data and is indexed by the tag.
74    let color = material_data[data_index].data_array[tag].color;
75
76    // Sample from the appropriate texture in the bindless textures array.
77    let texture_color = textureSample(
78        bindless_textures_2d[color_texture_index],
79        bindless_samplers_filtering[color_texture_sampler_index],
80        in.uv
81    ).rgb;
82
83} @else {
84
85    // In non-bindless mode, we only have one buffer, so we simply use the tag
86    // as an index into the array.
87    let color = material_data.data_array[tag].color;
88
89    let texture_color = textureSample(color_texture, color_texture_sampler, in.uv).rgb;
90
91}
92
93    // Modulate the texture by the appropriate tint color.
94    return vec4<f32>(color * texture_color, 1.0);
95}