1//! Very simple shader used to demonstrate how to get the world position and pass data
2//! between the vertex and fragment shader. Also shows the custom vertex layout.
3
4// First we import everything we need from bevy_pbr
5// A 2D shader would be very similar but import from bevy_sprite_render instead
6import bevy_pbr::render::{
7    mesh_functions,
8    view_transformations::position_world_to_clip
9};
10
11struct Vertex {
12    // This is needed if you are using batching and/or gpu preprocessing
13    // It's a built in so you don't need to define it in the vertex layout
14    @builtin(instance_index) instance_index: u32,
15    // Like we defined for the vertex layout
16    // position is at location 0
17    @if(VERTEX_POSITIONS_COMPRESSED)
18    @location(0) compressed_position: vec4<f32>,
19    @else
20    @location(0) position: vec3<f32>,
21    // and color at location 1
22    @if(VERTEX_COLORS)
23    @location(1) color: vec4<f32>,
24};
25
26/// This is the output of the vertex shader and we also use it as the input for the fragment shader
27struct VertexOutput {
28    @builtin(position) clip_position: vec4<f32>,
29    @location(0) world_position: vec4<f32>,
30    @if(VERTEX_COLORS)
31    @location(1) color: vec3<f32>,
32};
33
34@vertex
35fn vertex(vertex: Vertex) -> VertexOutput {
36    var out: VertexOutput;
37    // This is how bevy computes the world position
38    // The vertex.instance_index is very important. Especially if you are using batching and gpu preprocessing
39    var world_from_local = mesh_functions::get_world_from_local(vertex.instance_index);
40@if(VERTEX_POSITIONS_COMPRESSED) {
41    let mesh_metadata = bevy_pbr::render::mesh_functions::get_metadata(vertex.instance_index);
42    let vertex_position = bevy_render::utils::decompress_vertex_position(vertex.compressed_position, mesh_metadata.aabb_center, mesh_metadata.aabb_half_extents);
43}
44@else {
45    let vertex_position = vertex.position;
46}
47    out.world_position = mesh_functions::mesh_position_local_to_world(world_from_local, vec4(vertex_position, 1.0));
48    out.clip_position = position_world_to_clip(out.world_position.xyz);
49
50    @if(VERTEX_COLORS)
51    out.color = vertex.color.rgb;
52
53    return out;
54}
55
56@fragment
57fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
58    // We just use the raw vertex color if the mesh provides one, otherwise
59    // we fall back to a hardcoded color (e.g. for the rectangle mesh,
60    // which has no vertex color attribute).
61    @if(VERTEX_COLORS)
62    let color = in.color;
63    @else
64    let color = vec3<f32>(1.0, 1.0, 1.0);
65
66    // output the color directly
67    return vec4(color, 1.0);
68}