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 vevry similar but import from bevy_sprite instead
6#import bevy_pbr::{
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    @location(0) position: vec3<f32>,
18    // and color at location 1
19    @location(1) color: vec4<f32>,
20};
21
22// This is the output of the vertex shader and we also use it as the input for the fragment shader
23struct VertexOutput {
24    @builtin(position) clip_position: vec4<f32>,
25    @location(0) world_position: vec4<f32>,
26    @location(1) color: vec3<f32>,
27};
28
29@vertex
30fn vertex(vertex: Vertex) -> VertexOutput {
31    var out: VertexOutput;
32    // This is how bevy computes the world position
33    // The vertex.instance_index is very important. Esepecially if you are using batching and gpu preprocessing
34    var world_from_local = mesh_functions::get_world_from_local(vertex.instance_index);
35    out.world_position = mesh_functions::mesh_position_local_to_world(world_from_local, vec4(vertex.position, 1.0));
36    out.clip_position = position_world_to_clip(out.world_position.xyz);
37
38    // We just use the raw vertex color
39    out.color = vertex.color.rgb;
40
41    return out;
42}
43
44@fragment
45fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
46    // output the color directly
47    return vec4(in.color, 1.0);
48}